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<h1 style='display: inline' id='f3s-kubernetes-with-freebsd---part-8-observability'>f3s: Kubernetes with FreeBSD - Part 8: Observability</h1><br />
<br />
<span class='quote'>Published at 2025-12-06T23:58:24+02:00, last updated Mon 09 Mar 09:33:08 EET 2026</span><br />
<br />
<span>This is the 8th blog post about the f3s series for my self-hosting demands in a home lab. f3s? The "f" stands for FreeBSD, and the "3s" stands for k3s, the Kubernetes distribution I use on FreeBSD-based physical machines.</span><br />
<br />
<a class='textlink' href='./2024-11-17-f3s-kubernetes-with-freebsd-part-1.html'>2024-11-17 f3s: Kubernetes with FreeBSD - Part 1: Setting the stage</a><br />
<a class='textlink' href='./2024-12-03-f3s-kubernetes-with-freebsd-part-2.html'>2024-12-03 f3s: Kubernetes with FreeBSD - Part 2: Hardware and base installation</a><br />
<a class='textlink' href='./2025-02-01-f3s-kubernetes-with-freebsd-part-3.html'>2025-02-01 f3s: Kubernetes with FreeBSD - Part 3: Protecting from power cuts</a><br />
<a class='textlink' href='./2025-04-05-f3s-kubernetes-with-freebsd-part-4.html'>2025-04-05 f3s: Kubernetes with FreeBSD - Part 4: Rocky Linux Bhyve VMs</a><br />
<a class='textlink' href='./2025-05-11-f3s-kubernetes-with-freebsd-part-5.html'>2025-05-11 f3s: Kubernetes with FreeBSD - Part 5: WireGuard mesh network</a><br />
<a class='textlink' href='./2025-07-14-f3s-kubernetes-with-freebsd-part-6.html'>2025-07-14 f3s: Kubernetes with FreeBSD - Part 6: Storage</a><br />
<a class='textlink' href='./2025-10-02-f3s-kubernetes-with-freebsd-part-7.html'>2025-10-02 f3s: Kubernetes with FreeBSD - Part 7: k3s and first pod deployments</a><br />
<a class='textlink' href='./2025-12-07-f3s-kubernetes-with-freebsd-part-8.html'>2025-12-07 f3s: Kubernetes with FreeBSD - Part 8: Observability (You are currently reading this)</a><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-1/f3slogo.png'><img alt='f3s logo' title='f3s logo' src='./f3s-kubernetes-with-freebsd-part-1/f3slogo.png' /></a><br />
<br />
<h2 style='display: inline' id='table-of-contents'>Table of Contents</h2><br />
<br />
<ul>
<li><a href='#f3s-kubernetes-with-freebsd---part-8-observability'>f3s: Kubernetes with FreeBSD - Part 8: Observability</a></li>
<li>⇢ <a href='#introduction'>Introduction</a></li>
<li>⇢ <a href='#important-note-gitops-migration'>Important Note: GitOps Migration</a></li>
<li>⇢ <a href='#persistent-storage-recap'>Persistent storage recap</a></li>
<li>⇢ <a href='#the-monitoring-namespace'>The monitoring namespace</a></li>
<li>⇢ <a href='#installing-prometheus-and-grafana'>Installing Prometheus and Grafana</a></li>
<li>⇢ ⇢ <a href='#prerequisites'>Prerequisites</a></li>
<li>⇢ ⇢ <a href='#deploying-with-the-justfile'>Deploying with the Justfile</a></li>
<li>⇢ ⇢ <a href='#exposing-grafana-via-ingress'>Exposing Grafana via ingress</a></li>
<li>⇢ <a href='#installing-loki-and-alloy'>Installing Loki and Alloy</a></li>
<li>⇢ ⇢ <a href='#prerequisites'>Prerequisites</a></li>
<li>⇢ ⇢ <a href='#deploying-loki-and-alloy'>Deploying Loki and Alloy</a></li>
<li>⇢ ⇢ <a href='#configuring-alloy'>Configuring Alloy</a></li>
<li>⇢ ⇢ <a href='#adding-loki-as-a-grafana-data-source'>Adding Loki as a Grafana data source</a></li>
<li>⇢ <a href='#the-complete-monitoring-stack'>The complete monitoring stack</a></li>
<li>⇢ <a href='#using-the-observability-stack'>Using the observability stack</a></li>
<li>⇢ ⇢ <a href='#viewing-metrics-in-grafana'>Viewing metrics in Grafana</a></li>
<li>⇢ ⇢ <a href='#querying-logs-with-logql'>Querying logs with LogQL</a></li>
<li>⇢ ⇢ <a href='#creating-alerts'>Creating alerts</a></li>
<li>⇢ <a href='#monitoring-external-freebsd-hosts'>Monitoring external FreeBSD hosts</a></li>
<li>⇢ ⇢ <a href='#installing-node-exporter-on-freebsd'>Installing Node Exporter on FreeBSD</a></li>
<li>⇢ ⇢ <a href='#adding-freebsd-hosts-to-prometheus'>Adding FreeBSD hosts to Prometheus</a></li>
<li>⇢ ⇢ <a href='#freebsd-memory-metrics-compatibility'>FreeBSD memory metrics compatibility</a></li>
<li>⇢ ⇢ <a href='#disk-io-metrics-limitation'>Disk I/O metrics limitation</a></li>
<li>⇢ <a href='#zfs-monitoring-for-freebsd-servers'>ZFS Monitoring for FreeBSD Servers</a></li>
<li>⇢ ⇢ <a href='#node-exporter-zfs-collector'>Node Exporter ZFS Collector</a></li>
<li>⇢ ⇢ <a href='#verifying-zfs-metrics'>Verifying ZFS Metrics</a></li>
<li>⇢ ⇢ <a href='#zfs-recording-rules'>ZFS Recording Rules</a></li>
<li>⇢ ⇢ <a href='#grafana-dashboards'>Grafana Dashboards</a></li>
<li>⇢ ⇢ <a href='#deployment'>Deployment</a></li>
<li>⇢ ⇢ <a href='#verifying-zfs-metrics-in-prometheus'>Verifying ZFS Metrics in Prometheus</a></li>
<li>⇢ ⇢ <a href='#key-metrics-to-monitor'>Key Metrics to Monitor</a></li>
<li>⇢ ⇢ <a href='#zfs-pool-and-dataset-metrics-via-textfile-collector'>ZFS Pool and Dataset Metrics via Textfile Collector</a></li>
<li>⇢ <a href='#monitoring-external-openbsd-hosts'>Monitoring external OpenBSD hosts</a></li>
<li>⇢ ⇢ <a href='#installing-node-exporter-on-openbsd'>Installing Node Exporter on OpenBSD</a></li>
<li>⇢ ⇢ <a href='#adding-openbsd-hosts-to-prometheus'>Adding OpenBSD hosts to Prometheus</a></li>
<li>⇢ ⇢ <a href='#openbsd-memory-metrics-compatibility'>OpenBSD memory metrics compatibility</a></li>
<li>⇢ <a href='#distributed-tracing-with-grafana-tempo'>Distributed Tracing with Grafana Tempo</a></li>
<li>⇢ ⇢ <a href='#why-distributed-tracing'>Why Distributed Tracing?</a></li>
<li>⇢ ⇢ <a href='#deploying-grafana-tempo'>Deploying Grafana Tempo</a></li>
<li>⇢ <a href='#-configuration-strategy'>⇢# Configuration Strategy</a></li>
<li>⇢ <a href='#-tempo-deployment-files'>⇢# Tempo Deployment Files</a></li>
<li>⇢ <a href='#-installation'>⇢# Installation</a></li>
<li>⇢ ⇢ <a href='#configuring-grafana-alloy-for-trace-collection'>Configuring Grafana Alloy for Trace Collection</a></li>
<li>⇢ <a href='#-otlp-receiver-configuration'>⇢# OTLP Receiver Configuration</a></li>
<li>⇢ <a href='#-upgrade-alloy'>⇢# Upgrade Alloy</a></li>
<li>⇢ ⇢ <a href='#demo-tracing-application'>Demo Tracing Application</a></li>
<li>⇢ <a href='#-application-architecture'>⇢# Application Architecture</a></li>
<li>⇢ ⇢ <a href='#visualizing-traces-in-grafana'>Visualizing Traces in Grafana</a></li>
<li>⇢ <a href='#-accessing-traces'>⇢# Accessing Traces</a></li>
<li>⇢ <a href='#-service-graph-visualization'>⇢# Service Graph Visualization</a></li>
<li>⇢ ⇢ <a href='#correlation-between-observability-signals'>Correlation Between Observability Signals</a></li>
<li>⇢ <a href='#-traces-to-logs'>⇢# Traces-to-Logs</a></li>
<li>⇢ <a href='#-traces-to-metrics'>⇢# Traces-to-Metrics</a></li>
<li>⇢ <a href='#-logs-to-traces'>⇢# Logs-to-Traces</a></li>
<li>⇢ ⇢ <a href='#generating-traces-for-testing'>Generating Traces for Testing</a></li>
<li>⇢ ⇢ <a href='#verifying-the-complete-pipeline'>Verifying the Complete Pipeline</a></li>
<li>⇢ ⇢ <a href='#practical-example-viewing-a-distributed-trace'>Practical Example: Viewing a Distributed Trace</a></li>
<li>⇢ ⇢ <a href='#storage-and-retention'>Storage and Retention</a></li>
<li>⇢ ⇢ <a href='#configuration-files'>Configuration Files</a></li>
<li>⇢ <a href='#summary'>Summary</a></li>
</ul><br />
<h2 style='display: inline' id='introduction'>Introduction</h2><br />
<br />
<span>In this blog post, I set up a complete observability stack for the k3s cluster. Observability is crucial for understanding what's happening inside the cluster—whether its tracking resource usage, debugging issues, or analysing application behaviour. The stack consists of five main components, all deployed into the <span class='inlinecode'>monitoring</span> namespace:</span><br />
<br />
<ul>
<li>Prometheus: time-series database for metrics collection and alerting</li>
<li>Grafana: visualisation and dashboarding frontend</li>
<li>Loki: log aggregation system (like Prometheus, but for logs)</li>
<li>Alloy: telemetry collector that ships logs and traces from all pods to Loki and Tempo</li>
<li>Tempo: distributed tracing backend for request flow analysis across microservices</li>
</ul><br />
<span>Together, these form the "PLG" stack (Prometheus, Loki, Grafana) extended with Tempo for distributed tracing, which is a popular open-source alternative to commercial observability platforms.</span><br />
<br />
<span>All manifests for the f3s stack live in my configuration repository:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s'>codeberg.org/snonux/conf/f3s</a><br />
<br />
<h2 style='display: inline' id='important-note-gitops-migration'>Important Note: GitOps Migration</h2><br />
<br />
<span>**Note:** After publishing this blog post, the f3s cluster was migrated from imperative Helm deployments to declarative GitOps using ArgoCD. The Kubernetes manifests, Helm charts, and Justfiles in the repository have been reorganized for ArgoCD-based continuous deployment.</span><br />
<br />
<span>**To view the exact configuration as it existed when this blog post was written** (before the ArgoCD migration), check out the pre-ArgoCD revision:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ git clone https</font><font color="#F3E651">:</font><font color="#ff0000">//codeberg</font><font color="#F3E651">.</font><font color="#ff0000">org/snonux/conf</font><font color="#F3E651">.</font><font color="#ff0000">git</font>
<font color="#ff0000">$ cd conf</font>
<font color="#ff0000">$ git checkout 15a86f3 </font><i><font color="#ababab"># Last commit before ArgoCD migration</font></i>
<font color="#ff0000">$ cd f3s/prometheus</font><font color="#F3E651">/</font>
</pre>
<br />
<span>**Current master branch** contains the ArgoCD-managed versions with:</span><br />
<ul>
<li>Application manifests organized under <span class='inlinecode'>argocd-apps/{monitoring,services,infra,test}/</span></li>
<li>Resources organized under <span class='inlinecode'>prometheus/manifests/</span>, <span class='inlinecode'>loki/</span>, etc.</li>
<li>Justfiles updated to trigger ArgoCD syncs instead of direct Helm commands</li>
</ul><br />
<span>The deployment concepts and architecture remain the same—only the deployment method changed from imperative (<span class='inlinecode'>helm install/upgrade</span>) to declarative (GitOps with ArgoCD). </span><br />
<br />
<h2 style='display: inline' id='persistent-storage-recap'>Persistent storage recap</h2><br />
<br />
<span>All observability components need persistent storage so that metrics and logs survive pod restarts. As covered in Part 6 of this series, the cluster uses NFS-backed persistent volumes:</span><br />
<br />
<a class='textlink' href='./2025-07-14-f3s-kubernetes-with-freebsd-part-6.html'>f3s: Kubernetes with FreeBSD - Part 6: Storage</a><br />
<br />
<span>The FreeBSD hosts (<span class='inlinecode'>f0</span>, <span class='inlinecode'>f1</span>) serve as master-standby NFS servers, exporting ZFS datasets that are replicated across hosts using <span class='inlinecode'>zrepl</span>. The Rocky Linux k3s nodes (<span class='inlinecode'>r0</span>, <span class='inlinecode'>r1</span>, <span class='inlinecode'>r2</span>) mount these exports at <span class='inlinecode'>/data/nfs/k3svolumes</span>. This directory contains subdirectories for each application that needs persistent storage—including Prometheus, Grafana, and Loki.</span><br />
<br />
<span>For example, the observability stack uses these paths on the NFS share:</span><br />
<br />
<ul>
<li><span class='inlinecode'>/data/nfs/k3svolumes/prometheus/data</span> — Prometheus time-series database</li>
<li><span class='inlinecode'>/data/nfs/k3svolumes/grafana/data</span> — Grafana configuration, dashboards, and plugins</li>
<li><span class='inlinecode'>/data/nfs/k3svolumes/loki/data</span> — Loki log chunks and index</li>
<li><span class='inlinecode'>/data/nfs/k3svolumes/tempo/data</span> — Tempo trace data and WAL</li>
</ul><br />
<span>Each path gets a corresponding <span class='inlinecode'>PersistentVolume</span> and <span class='inlinecode'>PersistentVolumeClaim</span> in Kubernetes, allowing pods to mount them as regular volumes. Because the underlying storage is ZFS with replication, we get snapshots and redundancy for free.</span><br />
<br />
<h2 style='display: inline' id='the-monitoring-namespace'>The monitoring namespace</h2><br />
<br />
<span>First, I created the monitoring namespace where all observability components will live:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl create namespace monitoring</font>
<font color="#ff0000">namespace/monitoring created</font>
</pre>
<br />
<h2 style='display: inline' id='installing-prometheus-and-grafana'>Installing Prometheus and Grafana</h2><br />
<br />
<span>Prometheus and Grafana are deployed together using the <span class='inlinecode'>kube-prometheus-stack</span> Helm chart from the Prometheus community. This chart bundles Prometheus, Grafana, Alertmanager, and various exporters (Node Exporter, Kube State Metrics) into a single deployment. Ill explain what each component does in detail later when we look at the running pods.</span><br />
<br />
<h3 style='display: inline' id='prerequisites'>Prerequisites</h3><br />
<br />
<span>Add the Prometheus Helm chart repository:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ helm repo add prometheus-community https</font><font color="#F3E651">:</font><font color="#ff0000">//prometheus-community</font><font color="#F3E651">.</font><font color="#ff0000">github</font><font color="#F3E651">.</font><font color="#ff0000">io/helm-charts</font>
<font color="#ff0000">$ helm repo update</font>
</pre>
<br />
<span>Create the directories on the NFS server for persistent storage:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># mkdir -p /data/nfs/k3svolumes/prometheus/data</font></i>
<font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># mkdir -p /data/nfs/k3svolumes/grafana/data</font></i>
</pre>
<br />
<h3 style='display: inline' id='deploying-with-the-justfile'>Deploying with the Justfile</h3><br />
<br />
<span>The configuration repository contains a <span class='inlinecode'>Justfile</span> that automates the deployment. <span class='inlinecode'>just</span> is a handy command runner—think of it as a simpler, more modern alternative to <span class='inlinecode'>make</span>. I use it throughout the f3s repository to wrap repetitive Helm and kubectl commands:</span><br />
<br />
<a class='textlink' href='https://github.com/casey/just'>just - A handy way to save and run project-specific commands</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus'>codeberg.org/snonux/conf/f3s/prometheus</a><br />
<br />
<span>To install everything:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ cd conf/f3s/prometheus</font>
<font color="#ff0000">$ just install</font>
<font color="#ff0000">kubectl apply -f persistent-volumes</font><font color="#F3E651">.</font><font color="#ff0000">yaml</font>
<font color="#ff0000">persistentvolume/prometheus-data-pv created</font>
<font color="#ff0000">persistentvolume/grafana-data-pv created</font>
<font color="#ff0000">persistentvolumeclaim/grafana-data-pvc created</font>
<font color="#ff0000">helm install prometheus prometheus-community/kube-prometheus-stack </font><font color="#F3E651">\</font>
<font color="#ff0000"> --namespace monitoring -f persistence-values</font><font color="#F3E651">.</font><font color="#ff0000">yaml</font>
<font color="#ff0000">NAME</font><font color="#F3E651">:</font><font color="#ff0000"> prometheus</font>
<font color="#ff0000">LAST DEPLOYED</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#F3E651">...</font>
<font color="#ff0000">NAMESPACE</font><font color="#F3E651">:</font><font color="#ff0000"> monitoring</font>
<font color="#ff0000">STATUS</font><font color="#F3E651">:</font><font color="#ff0000"> deployed</font>
</pre>
<br />
<span>The <span class='inlinecode'>persistence-values.yaml</span> configures Prometheus and Grafana to use the NFS-backed persistent volumes I mentioned earlier, ensuring data survives pod restarts. It also enables scraping of etcd and kube-controller-manager metrics:</span><br />
<br />
<pre>
kubeEtcd:
enabled: true
endpoints:
- 192.168.2.120
- 192.168.2.121
- 192.168.2.122
service:
enabled: true
port: 2381
targetPort: 2381
kubeControllerManager:
enabled: true
endpoints:
- 192.168.2.120
- 192.168.2.121
- 192.168.2.122
service:
enabled: true
port: 10257
targetPort: 10257
serviceMonitor:
enabled: true
https: true
insecureSkipVerify: true
</pre>
<br />
<span>By default, k3s binds the controller-manager to localhost only and doesn't expose etcd metrics, so the "Kubernetes / Controller Manager" and "etcd" dashboards in Grafana will show no data. To fix both, add the following to <span class='inlinecode'>/etc/rancher/k3s/config.yaml</span> on each k3s server node:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># cat >> /etc/rancher/k3s/config.yaml << 'EOF'</font></i>
<font color="#ff0000">kube-controller-manager-arg</font><font color="#F3E651">:</font>
<font color="#ff0000"> - bind-address</font><font color="#F3E651">=</font><font color="#bb00ff">0.0</font><font color="#F3E651">.</font><font color="#bb00ff">0.0</font>
<font color="#ff0000">etcd-expose-metrics</font><font color="#F3E651">:</font><font color="#ff0000"> </font><b><font color="#ffffff">true</font></b>
<font color="#ff0000">EOF</font>
<font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># systemctl restart k3s</font></i>
</pre>
<br />
<span>Repeat for <span class='inlinecode'>r1</span> and <span class='inlinecode'>r2</span>. After restarting all nodes, the controller-manager metrics endpoint will be accessible and etcd metrics are available on port 2381. Prometheus can now scrape both.</span><br />
<br />
<span>Verify etcd metrics are exposed:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># curl -s http://127.0.0.1:2381/metrics | grep etcd_server_has_leader</font></i>
<font color="#ff0000">etcd_server_has_leader </font><font color="#bb00ff">1</font>
</pre>
<br />
<span>The full <span class='inlinecode'>persistence-values.yaml</span> and all other Prometheus configuration files are available on Codeberg:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus'>codeberg.org/snonux/conf/f3s/prometheus</a><br />
<br />
<span>The persistent volume definitions bind to specific paths on the NFS share using <span class='inlinecode'>hostPath</span> volumes—the same pattern used for other services in Part 7:</span><br />
<br />
<a class='textlink' href='./2025-10-02-f3s-kubernetes-with-freebsd-part-7.html'>f3s: Kubernetes with FreeBSD - Part 7: k3s and first pod deployments</a><br />
<br />
<h3 style='display: inline' id='exposing-grafana-via-ingress'>Exposing Grafana via ingress</h3><br />
<br />
<span>The chart also deploys an ingress for Grafana, making it accessible at <span class='inlinecode'>grafana.f3s.foo.zone</span>. The ingress configuration follows the same pattern as other services in the cluster—Traefik handles the routing internally, while the OpenBSD edge relays terminate TLS and forward traffic through WireGuard.</span><br />
<br />
<span>Once deployed, Grafana is accessible and comes pre-configured with Prometheus as a data source. You can verify the Prometheus service is running:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl get svc -n monitoring prometheus-kube-prometheus-prometheus</font>
<font color="#ff0000">NAME TYPE CLUSTER-IP PORT</font><font color="#F3E651">(</font><font color="#ff0000">S</font><font color="#F3E651">)</font>
<font color="#ff0000">prometheus-kube-prometheus-prometheus ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">152.163</font><font color="#ff0000"> </font><font color="#bb00ff">9090</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">8080</font><font color="#ff0000">/TCP</font>
</pre>
<br />
<span>Grafana connects to Prometheus using the internal service URL <span class='inlinecode'>http://prometheus-kube-prometheus-prometheus.monitoring.svc.cluster.local:9090</span>. The default Grafana credentials are <span class='inlinecode'>admin</span>/<span class='inlinecode'>prom-operator</span>, which should be changed immediately after first login.</span><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-prometheus.png'><img alt='Grafana dashboard showing Prometheus metrics' title='Grafana dashboard showing Prometheus metrics' src='./f3s-kubernetes-with-freebsd-part-8/grafana-prometheus.png' /></a><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-dashboard.png'><img alt='Grafana dashboard showing cluster metrics' title='Grafana dashboard showing cluster metrics' src='./f3s-kubernetes-with-freebsd-part-8/grafana-dashboard.png' /></a><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-etcd-dashboard.png'><img alt='Grafana etcd dashboard showing cluster health, RPC rate, disk sync duration, and peer round trip times' title='Grafana etcd dashboard showing cluster health, RPC rate, disk sync duration, and peer round trip times' src='./f3s-kubernetes-with-freebsd-part-8/grafana-etcd-dashboard.png' /></a><br />
<br />
<h2 style='display: inline' id='installing-loki-and-alloy'>Installing Loki and Alloy</h2><br />
<br />
<span>While Prometheus handles metrics, Loki handles logs. It's designed to be cost-effective and easy to operate—it doesn't index the contents of logs, only the metadata (labels), making it very efficient for storage.</span><br />
<br />
<span>Alloy is Grafana's telemetry collector (the successor to Promtail). It runs as a DaemonSet on each node, tails container logs, and ships them to Loki.</span><br />
<br />
<h3 style='display: inline' id='prerequisites'>Prerequisites</h3><br />
<br />
<span>Create the data directory on the NFS server:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">[</font><font color="#ff0000">root@r0 </font><font color="#F3E651">~]</font><i><font color="#ababab"># mkdir -p /data/nfs/k3svolumes/loki/data</font></i>
</pre>
<br />
<h3 style='display: inline' id='deploying-loki-and-alloy'>Deploying Loki and Alloy</h3><br />
<br />
<span>The Loki configuration also lives in the repository:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/loki'>codeberg.org/snonux/conf/f3s/loki</a><br />
<br />
<span>To install:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ cd conf/f3s/loki</font>
<font color="#ff0000">$ just install</font>
<font color="#ff0000">helm repo add grafana https</font><font color="#F3E651">:</font><font color="#ff0000">//grafana</font><font color="#F3E651">.</font><font color="#ff0000">github</font><font color="#F3E651">.</font><font color="#ff0000">io/helm-charts </font><font color="#F3E651">||</font><font color="#ff0000"> </font><b><font color="#ffffff">true</font></b>
<font color="#ff0000">helm repo update</font>
<font color="#ff0000">kubectl apply -f persistent-volumes</font><font color="#F3E651">.</font><font color="#ff0000">yaml</font>
<font color="#ff0000">persistentvolume/loki-data-pv created</font>
<font color="#ff0000">persistentvolumeclaim/loki-data-pvc created</font>
<font color="#ff0000">helm install loki grafana/loki --namespace monitoring -f values</font><font color="#F3E651">.</font><font color="#ff0000">yaml</font>
<font color="#ff0000">NAME</font><font color="#F3E651">:</font><font color="#ff0000"> loki</font>
<font color="#ff0000">LAST DEPLOYED</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#F3E651">...</font>
<font color="#ff0000">NAMESPACE</font><font color="#F3E651">:</font><font color="#ff0000"> monitoring</font>
<font color="#ff0000">STATUS</font><font color="#F3E651">:</font><font color="#ff0000"> deployed</font>
<font color="#F3E651">...</font>
<font color="#ff0000">helm install alloy grafana/alloy --namespace monitoring -f alloy-values</font><font color="#F3E651">.</font><font color="#ff0000">yaml</font>
<font color="#ff0000">NAME</font><font color="#F3E651">:</font><font color="#ff0000"> alloy</font>
<font color="#ff0000">LAST DEPLOYED</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#F3E651">...</font>
<font color="#ff0000">NAMESPACE</font><font color="#F3E651">:</font><font color="#ff0000"> monitoring</font>
<font color="#ff0000">STATUS</font><font color="#F3E651">:</font><font color="#ff0000"> deployed</font>
</pre>
<br />
<span>Loki runs in single-binary mode with a single replica (<span class='inlinecode'>loki-0</span>), which is appropriate for a home lab cluster. This means there's only one Loki pod running at any time. If the node hosting Loki fails, Kubernetes will automatically reschedule the pod to another worker node—but there will be a brief downtime (typically under a minute) while this happens. For my home lab use case, this is perfectly acceptable.</span><br />
<br />
<span>For full high-availability, you'd deploy Loki in microservices mode with separate read, write, and backend components, backed by object storage like S3 or MinIO instead of local filesystem storage. That's a more complex setup that I might explore in a future blog post—but for now, the single-binary mode with NFS-backed persistence strikes the right balance between simplicity and durability.</span><br />
<br />
<h3 style='display: inline' id='configuring-alloy'>Configuring Alloy</h3><br />
<br />
<span>Alloy is configured via <span class='inlinecode'>alloy-values.yaml</span> to discover all pods in the cluster and forward their logs to Loki:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">discovery</font><font color="#F3E651">.</font><font color="#ff0000">kubernetes </font><font color="#bb00ff">"pods"</font><font color="#ff0000"> {</font>
<font color="#ff0000"> role </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"pod"</font>
<font color="#ff0000">}</font>
<font color="#ff0000">discovery</font><font color="#F3E651">.</font><font color="#ff0000">relabel </font><font color="#bb00ff">"pods"</font><font color="#ff0000"> {</font>
<font color="#ff0000"> targets </font><font color="#F3E651">=</font><font color="#ff0000"> discovery</font><font color="#F3E651">.</font><font color="#ff0000">kubernetes</font><font color="#F3E651">.</font><font color="#ff0000">pods</font><font color="#F3E651">.</font><font color="#ff0000">targets</font>
<font color="#ff0000"> rule {</font>
<font color="#ff0000"> source_labels </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#F3E651">[</font><font color="#bb00ff">"__meta_kubernetes_namespace"</font><font color="#F3E651">]</font>
<font color="#ff0000"> target_label </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"namespace"</font>
<font color="#ff0000"> }</font>
<font color="#ff0000"> rule {</font>
<font color="#ff0000"> source_labels </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#F3E651">[</font><font color="#bb00ff">"__meta_kubernetes_pod_name"</font><font color="#F3E651">]</font>
<font color="#ff0000"> target_label </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"pod"</font>
<font color="#ff0000"> }</font>
<font color="#ff0000"> rule {</font>
<font color="#ff0000"> source_labels </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#F3E651">[</font><font color="#bb00ff">"__meta_kubernetes_pod_container_name"</font><font color="#F3E651">]</font>
<font color="#ff0000"> target_label </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"container"</font>
<font color="#ff0000"> }</font>
<font color="#ff0000"> rule {</font>
<font color="#ff0000"> source_labels </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#F3E651">[</font><font color="#bb00ff">"__meta_kubernetes_pod_label_app"</font><font color="#F3E651">]</font>
<font color="#ff0000"> target_label </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"app"</font>
<font color="#ff0000"> }</font>
<font color="#ff0000">}</font>
<font color="#ff0000">loki</font><font color="#F3E651">.</font><b><font color="#ffffff">source</font></b><font color="#F3E651">.</font><font color="#ff0000">kubernetes </font><font color="#bb00ff">"pods"</font><font color="#ff0000"> {</font>
<font color="#ff0000"> targets </font><font color="#F3E651">=</font><font color="#ff0000"> discovery</font><font color="#F3E651">.</font><font color="#ff0000">relabel</font><font color="#F3E651">.</font><font color="#ff0000">pods</font><font color="#F3E651">.</font><font color="#ff0000">output</font>
<font color="#ff0000"> forward_to </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#F3E651">[</font><font color="#ff0000">loki</font><font color="#F3E651">.</font><font color="#ff0000">write</font><font color="#F3E651">.</font><font color="#ff0000">default</font><font color="#F3E651">.</font><font color="#ff0000">receiver</font><font color="#F3E651">]</font>
<font color="#ff0000">}</font>
<font color="#ff0000">loki</font><font color="#F3E651">.</font><font color="#ff0000">write </font><font color="#bb00ff">"default"</font><font color="#ff0000"> {</font>
<font color="#ff0000"> endpoint {</font>
<font color="#ff0000"> url </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#bb00ff">"http://loki.monitoring.svc.cluster.local:3100/loki/api/v1/push"</font>
<font color="#ff0000"> }</font>
<font color="#ff0000">}</font>
</pre>
<br />
<span>This configuration automatically labels each log line with the namespace, pod name, container name, and app label, making it easy to filter logs in Grafana.</span><br />
<br />
<h3 style='display: inline' id='adding-loki-as-a-grafana-data-source'>Adding Loki as a Grafana data source</h3><br />
<br />
<span>Loki doesn't have its own web UI—you query it through Grafana. First, verify the Loki service is running:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl get svc -n monitoring loki</font>
<font color="#ff0000">NAME TYPE CLUSTER-IP PORT</font><font color="#F3E651">(</font><font color="#ff0000">S</font><font color="#F3E651">)</font>
<font color="#ff0000">loki ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">64.60</font><font color="#ff0000"> </font><font color="#bb00ff">3100</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">9095</font><font color="#ff0000">/TCP</font>
</pre>
<br />
<span>To add Loki as a data source in Grafana:</span><br />
<br />
<ul>
<li>Navigate to Configuration → Data Sources</li>
<li>Click "Add data source"</li>
<li>Select "Loki"</li>
<li>Set the URL to: <span class='inlinecode'>http://loki.monitoring.svc.cluster.local:3100</span></li>
<li>Click "Save & Test"</li>
</ul><br />
<span>Once configured, you can explore logs in Grafana's "Explore" view. I'll show some example queries in the "Using the observability stack" section below.</span><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/loki-explore.png'><img alt='Exploring logs in Grafana with Loki' title='Exploring logs in Grafana with Loki' src='./f3s-kubernetes-with-freebsd-part-8/loki-explore.png' /></a><br />
<br />
<h2 style='display: inline' id='the-complete-monitoring-stack'>The complete monitoring stack</h2><br />
<br />
<span>After deploying everything, here's what's running in the monitoring namespace:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl get pods -n monitoring</font>
<font color="#ff0000">NAME READY STATUS RESTARTS AGE</font>
<font color="#ff0000">alertmanager-prometheus-kube-prometheus-alertmanager-</font><font color="#bb00ff">0</font><font color="#ff0000"> </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">alloy-g5fgj </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 29m</font>
<font color="#ff0000">alloy-nfw8w </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 29m</font>
<font color="#ff0000">alloy-tg9vj </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 29m</font>
<font color="#ff0000">loki-</font><font color="#bb00ff">0</font><font color="#ff0000"> </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 25m</font>
<font color="#ff0000">prometheus-grafana-868f9dc7cf-lg2vl </font><font color="#bb00ff">3</font><font color="#F3E651">/</font><font color="#bb00ff">3</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-kube-prometheus-operator-8d7bbc48c-p4sf4 </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-kube-state-metrics-7c5fb9d798-hh2fx </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-prometheus-kube-prometheus-prometheus-</font><font color="#bb00ff">0</font><font color="#ff0000"> </font><font color="#bb00ff">2</font><font color="#F3E651">/</font><font color="#bb00ff">2</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-prometheus-node-exporter-2nsg9 </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-prometheus-node-exporter-mqr</font><font color="#bb00ff">25</font><font color="#ff0000"> </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">prometheus-prometheus-node-exporter-wp4ds </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 42d</font>
<font color="#ff0000">tempo-</font><font color="#bb00ff">0</font><font color="#ff0000"> </font><font color="#bb00ff">1</font><font color="#F3E651">/</font><font color="#bb00ff">1</font><font color="#ff0000"> Running </font><font color="#bb00ff">0</font><font color="#ff0000"> 1d</font>
</pre>
<br />
<span>Note: Tempo (<span class='inlinecode'>tempo-0</span>) is deployed later in this post in the "Distributed Tracing with Grafana Tempo" section. It is included in the pod listing here for completeness.</span><br />
<br />
<span>And the services:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl get svc -n monitoring</font>
<font color="#ff0000">NAME TYPE CLUSTER-IP PORT</font><font color="#F3E651">(</font><font color="#ff0000">S</font><font color="#F3E651">)</font>
<font color="#ff0000">alertmanager-operated ClusterIP None </font><font color="#bb00ff">9093</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">9094</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">alloy ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">74.14</font><font color="#ff0000"> </font><font color="#bb00ff">12345</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">loki ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">64.60</font><font color="#ff0000"> </font><font color="#bb00ff">3100</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">9095</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">loki-headless ClusterIP None </font><font color="#bb00ff">3100</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-grafana ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">46.82</font><font color="#ff0000"> </font><font color="#bb00ff">80</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-kube-prometheus-alertmanager ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">208.43</font><font color="#ff0000"> </font><font color="#bb00ff">9093</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">8080</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-kube-prometheus-operator ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">246.121</font><font color="#ff0000"> </font><font color="#bb00ff">443</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-kube-prometheus-prometheus ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">152.163</font><font color="#ff0000"> </font><font color="#bb00ff">9090</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">8080</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-kube-state-metrics ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">64.26</font><font color="#ff0000"> </font><font color="#bb00ff">8080</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">prometheus-prometheus-node-exporter ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">127.242</font><font color="#ff0000"> </font><font color="#bb00ff">9100</font><font color="#ff0000">/TCP</font>
<font color="#ff0000">tempo ClusterIP </font><font color="#bb00ff">10.43</font><font color="#F3E651">.</font><font color="#bb00ff">91.44</font><font color="#ff0000"> </font><font color="#bb00ff">3200</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">4317</font><font color="#ff0000">/TCP</font><font color="#F3E651">,</font><font color="#bb00ff">4318</font><font color="#ff0000">/TCP</font>
</pre>
<br />
<span>Let me break down what each pod does:</span><br />
<br />
<ul>
<li><span class='inlinecode'>alertmanager-prometheus-kube-prometheus-alertmanager-0</span>: the Alertmanager instance that receives alerts from Prometheus, deduplicates them, groups related alerts together, and routes notifications to the appropriate receivers (email, Slack, PagerDuty, etc.). It runs as a StatefulSet with persistent storage for silences and notification state.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>alloy-g5fgj, alloy-nfw8w, alloy-tg9vj</span>: three Alloy pods running as a DaemonSet, one on each k3s node. Each pod tails the container logs from its local node via the Kubernetes API and forwards them to Loki. This ensures log collection continues even if a node becomes isolated from the others.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>loki-0</span>: the single Loki instance running in single-binary mode. It receives log streams from Alloy, stores them in chunks on the NFS-backed persistent volume, and serves queries from Grafana. The <span class='inlinecode'>-0</span> suffix indicates it's a StatefulSet pod.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>prometheus-grafana-...</span>: the Grafana web interface for visualising metrics and logs. It comes pre-configured with Prometheus as a data source and includes dozens of dashboards for Kubernetes monitoring. Dashboards, users, and settings are persisted to the NFS share.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>prometheus-kube-prometheus-operator-...</span>: the Prometheus Operator that watches for custom resources (ServiceMonitor, PodMonitor, PrometheusRule) and automatically configures Prometheus to scrape new targets. This allows applications to declare their own monitoring requirements.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>prometheus-kube-state-metrics-...</span>: generates metrics about the state of Kubernetes objects themselves: how many pods are running, pending, or failed; deployment replica counts; node conditions; PVC status; and more. Essential for cluster-level dashboards.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>prometheus-prometheus-kube-prometheus-prometheus-0</span>: the Prometheus server that scrapes metrics from all configured targets (pods, services, nodes), stores them in a time-series database, evaluates alerting rules, and serves queries to Grafana.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>prometheus-prometheus-node-exporter-...</span>: three Node Exporter pods running as a DaemonSet, one on each node. They expose hardware and OS-level metrics: CPU usage, memory, disk I/O, filesystem usage, network statistics, and more. These feed the "Node Exporter" dashboards in Grafana.</li>
</ul><br />
<ul>
<li><span class='inlinecode'>tempo-0</span>: the Grafana Tempo instance for distributed tracing. It receives trace data from Alloy via OTLP (OpenTelemetry Protocol), stores traces on the NFS-backed persistent volume, and serves queries to Grafana. Tempo is covered in detail in the "Distributed Tracing with Grafana Tempo" section later in this post.</li>
</ul><br />
<h2 style='display: inline' id='using-the-observability-stack'>Using the observability stack</h2><br />
<br />
<h3 style='display: inline' id='viewing-metrics-in-grafana'>Viewing metrics in Grafana</h3><br />
<br />
<span>The kube-prometheus-stack comes with many pre-built dashboards. Some useful ones include:</span><br />
<br />
<ul>
<li>Kubernetes / Compute Resources / Cluster: overview of CPU and memory usage across the cluster</li>
<li>Kubernetes / Compute Resources / Namespace (Pods): resource usage by namespace</li>
<li>Node Exporter / Nodes: detailed host metrics like disk I/O, network, and CPU</li>
</ul><br />
<h3 style='display: inline' id='querying-logs-with-logql'>Querying logs with LogQL</h3><br />
<br />
<span>In Grafana's Explore view, select Loki as the data source and try queries like:</span><br />
<br />
<pre>
# All logs from the services namespace
{namespace="services"}
# Logs from pods matching a pattern
{pod=~"miniflux.*"}
# Filter by log content
{namespace="services"} |= "error"
# Parse JSON logs and filter
{namespace="services"} | json | level="error"
</pre>
<br />
<h3 style='display: inline' id='creating-alerts'>Creating alerts</h3><br />
<br />
<span>Prometheus supports alerting rules that can notify you when something goes wrong. The kube-prometheus-stack includes many default alerts for common issues like high CPU usage, pod crashes, and node problems. These can be customised via PrometheusRule CRDs.</span><br />
<br />
<h2 style='display: inline' id='monitoring-external-freebsd-hosts'>Monitoring external FreeBSD hosts</h2><br />
<br />
<span>The observability stack can also monitor servers outside the Kubernetes cluster. The FreeBSD hosts (<span class='inlinecode'>f0</span>, <span class='inlinecode'>f1</span>, <span class='inlinecode'>f2</span>) that serve NFS storage can be added to Prometheus using the Node Exporter.</span><br />
<br />
<h3 style='display: inline' id='installing-node-exporter-on-freebsd'>Installing Node Exporter on FreeBSD</h3><br />
<br />
<span>On each FreeBSD host, install the node_exporter package:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">paul@f0</font><font color="#F3E651">:~</font><font color="#ff0000"> </font><font color="#F3E651">%</font><font color="#ff0000"> doas pkg install -y node_exporter</font>
</pre>
<br />
<span>Enable the service to start at boot:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">paul@f0</font><font color="#F3E651">:~</font><font color="#ff0000"> </font><font color="#F3E651">%</font><font color="#ff0000"> doas sysrc </font><font color="#ff0000">node_exporter_enable</font><font color="#F3E651">=</font><font color="#ff0000">YES</font>
<font color="#ff0000">node_exporter_enable</font><font color="#F3E651">:</font><font color="#ff0000"> -</font><font color="#F3E651">></font><font color="#ff0000"> YES</font>
</pre>
<br />
<span>Configure node_exporter to listen on the WireGuard interface. This ensures metrics are only accessible through the secure tunnel, not the public network. Replace the IP with the host's WireGuard address:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">paul@f0</font><font color="#F3E651">:~</font><font color="#ff0000"> </font><font color="#F3E651">%</font><font color="#ff0000"> doas sysrc </font><font color="#ff0000">node_exporter_args</font><font color="#F3E651">=</font><font color="#bb00ff">'--web.listen-address=192.168.2.130:9100'</font>
<font color="#ff0000">node_exporter_args</font><font color="#F3E651">:</font><font color="#ff0000"> -</font><font color="#F3E651">></font><font color="#ff0000"> --web</font><font color="#F3E651">.</font><font color="#ff0000">listen-address</font><font color="#F3E651">=</font><font color="#bb00ff">192.168</font><font color="#F3E651">.</font><font color="#bb00ff">2.130</font><font color="#F3E651">:</font><font color="#bb00ff">9100</font>
</pre>
<br />
<span>Start the service:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">paul@f0</font><font color="#F3E651">:~</font><font color="#ff0000"> </font><font color="#F3E651">%</font><font color="#ff0000"> doas service node_exporter start</font>
<font color="#ff0000">Starting node_exporter</font><font color="#F3E651">.</font>
</pre>
<br />
<span>Verify it's running:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">paul@f0</font><font color="#F3E651">:~</font><font color="#ff0000"> </font><font color="#F3E651">%</font><font color="#ff0000"> curl -s http</font><font color="#F3E651">://</font><font color="#bb00ff">192.168</font><font color="#F3E651">.</font><font color="#bb00ff">2.130</font><font color="#F3E651">:</font><font color="#bb00ff">9100</font><font color="#ff0000">/metrics </font><font color="#F3E651">|</font><font color="#ff0000"> head -</font><font color="#bb00ff">3</font>
<i><font color="#ababab"># HELP go_gc_duration_seconds A summary of the wall-time pause...</font></i>
<i><font color="#ababab"># TYPE go_gc_duration_seconds summary</font></i>
<font color="#ff0000">go_gc_duration_seconds{</font><font color="#ff0000">quantile</font><font color="#F3E651">=</font><font color="#bb00ff">"0"</font><font color="#ff0000">} </font><font color="#bb00ff">0</font>
</pre>
<br />
<span>Repeat for the other FreeBSD hosts (<span class='inlinecode'>f1</span>, <span class='inlinecode'>f2</span>) with their respective WireGuard IPs.</span><br />
<br />
<h3 style='display: inline' id='adding-freebsd-hosts-to-prometheus'>Adding FreeBSD hosts to Prometheus</h3><br />
<br />
<span>Create a file <span class='inlinecode'>additional-scrape-configs.yaml</span> in the prometheus configuration directory:</span><br />
<br />
<pre>
- job_name: 'node-exporter'
static_configs:
- targets:
- '192.168.2.130:9100' # f0 via WireGuard
- '192.168.2.131:9100' # f1 via WireGuard
- '192.168.2.132:9100' # f2 via WireGuard
labels:
os: freebsd
</pre>
<br />
<span>The <span class='inlinecode'>job_name</span> must be <span class='inlinecode'>node-exporter</span> to match the existing dashboards. The <span class='inlinecode'>os: freebsd</span> label allows filtering these hosts separately if needed.</span><br />
<br />
<span>Create a Kubernetes secret from this file:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ kubectl create secret generic additional-scrape-configs </font><font color="#F3E651">\</font>
<font color="#ff0000"> --from-file</font><font color="#F3E651">=</font><font color="#ff0000">additional-scrape-configs</font><font color="#F3E651">.</font><font color="#ff0000">yaml </font><font color="#F3E651">\</font>
<font color="#ff0000"> -n monitoring</font>
</pre>
<br />
<span>Update <span class='inlinecode'>persistence-values.yaml</span> to reference the secret:</span><br />
<br />
<pre>
prometheus:
prometheusSpec:
additionalScrapeConfigsSecret:
enabled: true
name: additional-scrape-configs
key: additional-scrape-configs.yaml
</pre>
<br />
<span>Upgrade the Prometheus deployment:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">$ just upgrade</font>
</pre>
<br />
<span>After a minute or so, the FreeBSD hosts appear in the Prometheus targets and in the Node Exporter dashboards in Grafana.</span><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-freebsd-nodes.png'><img alt='FreeBSD hosts in the Node Exporter dashboard' title='FreeBSD hosts in the Node Exporter dashboard' src='./f3s-kubernetes-with-freebsd-part-8/grafana-freebsd-nodes.png' /></a><br />
<br />
<h3 style='display: inline' id='freebsd-memory-metrics-compatibility'>FreeBSD memory metrics compatibility</h3><br />
<br />
<span>The default Node Exporter dashboards are designed for Linux and expect metrics like <span class='inlinecode'>node_memory_MemAvailable_bytes</span>. FreeBSD uses different metric names (<span class='inlinecode'>node_memory_size_bytes</span>, <span class='inlinecode'>node_memory_free_bytes</span>, etc.), so memory panels will show "No data" out of the box.</span><br />
<br />
<span>To fix this, I created a PrometheusRule that generates synthetic Linux-compatible metrics from the FreeBSD equivalents:</span><br />
<br />
<pre>
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
name: freebsd-memory-rules
namespace: monitoring
labels:
release: prometheus
spec:
groups:
- name: freebsd-memory
rules:
- record: node_memory_MemTotal_bytes
expr: node_memory_size_bytes{os="freebsd"}
- record: node_memory_MemAvailable_bytes
expr: |
node_memory_free_bytes{os="freebsd"}
+ node_memory_inactive_bytes{os="freebsd"}
+ node_memory_cache_bytes{os="freebsd"}
- record: node_memory_MemFree_bytes
expr: node_memory_free_bytes{os="freebsd"}
- record: node_memory_Buffers_bytes
expr: node_memory_buffer_bytes{os="freebsd"}
- record: node_memory_Cached_bytes
expr: node_memory_cache_bytes{os="freebsd"}
</pre>
<br />
<span>This file is saved as <span class='inlinecode'>freebsd-recording-rules.yaml</span> and applied as part of the Prometheus installation. The <span class='inlinecode'>os="freebsd"</span> label (set in the scrape config) ensures these rules only apply to FreeBSD hosts. After applying, the memory panels in the Node Exporter dashboards populate correctly for FreeBSD.</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus/freebsd-recording-rules.yaml'>freebsd-recording-rules.yaml on Codeberg</a><br />
<br />
<h3 style='display: inline' id='disk-io-metrics-limitation'>Disk I/O metrics limitation</h3><br />
<br />
<span>Unlike memory metrics, disk I/O metrics (<span class='inlinecode'>node_disk_read_bytes_total</span>, <span class='inlinecode'>node_disk_written_bytes_total</span>, etc.) are not available on FreeBSD. The Linux diskstats collector that provides these metrics doesn't have a FreeBSD equivalent in the node_exporter.</span><br />
<br />
<span>The disk I/O panels in the Node Exporter dashboards will show "No data" for FreeBSD hosts. FreeBSD does expose ZFS-specific metrics (<span class='inlinecode'>node_zfs_arcstats_*</span>) for ARC cache performance, and per-dataset I/O stats are available via <span class='inlinecode'>sysctl kstat.zfs</span>, but mapping these to the Linux-style metrics the dashboards expect is non-trivial. To address this, I created custom ZFS-specific dashboards, covered in the next section.</span><br />
<br />
<h2 style='display: inline' id='zfs-monitoring-for-freebsd-servers'>ZFS Monitoring for FreeBSD Servers</h2><br />
<br />
<span>The FreeBSD servers (f0, f1, f2) that provide NFS storage to the k3s cluster have ZFS filesystems. Monitoring ZFS performance is crucial for understanding storage performance and cache efficiency.</span><br />
<br />
<h3 style='display: inline' id='node-exporter-zfs-collector'>Node Exporter ZFS Collector</h3><br />
<br />
<span>The node_exporter running on each FreeBSD server (v1.9.1) includes a built-in ZFS collector that exposes metrics via sysctls. The ZFS collector is enabled by default and provides:</span><br />
<br />
<ul>
<li>ARC (Adaptive Replacement Cache) statistics</li>
<li>Cache hit/miss rates</li>
<li>Memory usage and allocation</li>
<li>MRU/MFU cache breakdown</li>
<li>Data vs metadata distribution</li>
</ul><br />
<h3 style='display: inline' id='verifying-zfs-metrics'>Verifying ZFS Metrics</h3><br />
<br />
<span>On any FreeBSD server, check that ZFS metrics are being exposed:</span><br />
<br />
<pre>
paul@f0:~ % curl -s http://localhost:9100/metrics | grep node_zfs_arcstats | wc -l
69
</pre>
<br />
<span>The metrics are automatically scraped by Prometheus through the existing static configuration in additional-scrape-configs.yaml which targets all FreeBSD servers on port 9100 with the os: freebsd label.</span><br />
<br />
<h3 style='display: inline' id='zfs-recording-rules'>ZFS Recording Rules</h3><br />
<br />
<span>Created recording rules for easier dashboard consumption in zfs-recording-rules.yaml:</span><br />
<br />
<pre>
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
name: freebsd-zfs-rules
namespace: monitoring
labels:
release: prometheus
spec:
groups:
- name: freebsd-zfs-arc
interval: 30s
rules:
- record: node_zfs_arc_hit_rate_percent
expr: |
100 * (
rate(node_zfs_arcstats_hits_total{os="freebsd"}[5m]) /
(rate(node_zfs_arcstats_hits_total{os="freebsd"}[5m]) +
rate(node_zfs_arcstats_misses_total{os="freebsd"}[5m]))
)
labels:
os: freebsd
- record: node_zfs_arc_memory_usage_percent
expr: |
100 * (
node_zfs_arcstats_size_bytes{os="freebsd"} /
node_zfs_arcstats_c_max_bytes{os="freebsd"}
)
labels:
os: freebsd
# Additional rules for metadata %, target %, MRU/MFU %, etc.
</pre>
<br />
<span>These recording rules calculate:</span><br />
<br />
<ul>
<li>ARC hit rate percentage</li>
<li>ARC memory usage percentage (current vs maximum)</li>
<li>ARC target percentage (target vs maximum)</li>
<li>Metadata vs data percentages</li>
<li>MRU vs MFU cache percentages</li>
<li>Demand data and metadata hit rates</li>
</ul><br />
<h3 style='display: inline' id='grafana-dashboards'>Grafana Dashboards</h3><br />
<br />
<span>Created two comprehensive ZFS monitoring dashboards (zfs-dashboards.yaml):</span><br />
<br />
<span>**Dashboard 1: FreeBSD ZFS (per-host detailed view)**</span><br />
<br />
<span>Includes variables to select:</span><br />
<br />
<ul>
<li>FreeBSD server (f0, f1, or f2)</li>
<li>ZFS pool (zdata, zroot, or all)</li>
</ul><br />
<span>Pool Overview Row:</span><br />
<br />
<ul>
<li>Pool Capacity gauge (with thresholds: green <70%, yellow <85%, red >85%)</li>
<li>Pool Health status (ONLINE/DEGRADED/FAULTED with color coding)</li>
<li>Total Pool Size stat</li>
<li>Free Space stat</li>
<li>Pool Space Usage Over Time (stacked: used + free)</li>
<li>Pool Capacity Trend time series</li>
</ul><br />
<span>Dataset Statistics Row:</span><br />
<br />
<ul>
<li>Table showing all datasets with columns: Pool, Dataset, Used, Available, Referenced</li>
<li>Automatically filters by selected pool</li>
</ul><br />
<span>ARC Cache Statistics Row:</span><br />
<br />
<ul>
<li>ARC Hit Rate gauge (red <70%, yellow <90%, green >=90%)</li>
<li>ARC Size time series (current, target, max)</li>
<li>ARC Memory Usage percentage gauge</li>
<li>ARC Hits vs Misses rate</li>
<li>ARC Data vs Metadata stacked time series</li>
</ul><br />
<span>**Dashboard 2: FreeBSD ZFS Summary (cluster-wide overview)**</span><br />
<br />
<span>Cluster-Wide Pool Statistics Row:</span><br />
<br />
<ul>
<li>Total Storage Capacity across all servers</li>
<li>Total Used space</li>
<li>Total Free space</li>
<li>Average Pool Capacity gauge</li>
<li>Pool Health Status (worst case across cluster)</li>
<li>Total Pool Space Usage Over Time</li>
<li>Per-Pool Capacity time series (all pools on all hosts)</li>
</ul><br />
<span>Per-Host Pool Breakdown Row:</span><br />
<br />
<ul>
<li>Bar gauge showing capacity by host and pool</li>
<li>Table with all pools: Host, Pool, Size, Used, Free, Capacity %, Health</li>
</ul><br />
<span>Cluster-Wide ARC Statistics Row:</span><br />
<br />
<ul>
<li>Average ARC Hit Rate gauge across all hosts</li>
<li>ARC Hit Rate by Host time series</li>
<li>Total ARC Size Across Cluster</li>
<li>Total ARC Hits vs Misses (cluster-wide sum)</li>
<li>ARC Size by Host</li>
</ul><br />
<span>Dashboard Visualization:</span><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-dashboard.png'><img alt='ZFS monitoring dashboard in Grafana showing pool capacity, health, and I/O throughput' title='ZFS monitoring dashboard in Grafana showing pool capacity, health, and I/O throughput' src='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-dashboard.png' /></a><br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-arc-stats.png'><img alt='ZFS ARC cache statistics showing hit rate, memory usage, and size trends' title='ZFS ARC cache statistics showing hit rate, memory usage, and size trends' src='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-arc-stats.png' /></a><br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-datasets.png'><img alt='ZFS datasets table and ARC data vs metadata breakdown' title='ZFS datasets table and ARC data vs metadata breakdown' src='./f3s-kubernetes-with-freebsd-part-8/grafana-zfs-datasets.png' /></a><br />
<br />
<h3 style='display: inline' id='deployment'>Deployment</h3><br />
<br />
<span>Applied the resources to the cluster:</span><br />
<br />
<pre>
cd /home/paul/git/conf/f3s/prometheus
kubectl apply -f zfs-recording-rules.yaml
kubectl apply -f zfs-dashboards.yaml
</pre>
<br />
<span>Updated Justfile to include ZFS recording rules in install and upgrade targets:</span><br />
<br />
<pre>
install:
kubectl apply -f persistent-volumes.yaml
kubectl create secret generic additional-scrape-configs --from-file=additional-scrape-configs.yaml -n monitoring --dry-run=client -o yaml | kubectl apply -f -
helm install prometheus prometheus-community/kube-prometheus-stack --namespace monitoring -f persistence-values.yaml
kubectl apply -f freebsd-recording-rules.yaml
kubectl apply -f openbsd-recording-rules.yaml
kubectl apply -f zfs-recording-rules.yaml
just -f grafana-ingress/Justfile install
</pre>
<br />
<h3 style='display: inline' id='verifying-zfs-metrics-in-prometheus'>Verifying ZFS Metrics in Prometheus</h3><br />
<br />
<span>Check that ZFS metrics are being collected:</span><br />
<br />
<pre>
kubectl exec -n monitoring prometheus-prometheus-kube-prometheus-prometheus-0 -c prometheus -- \
wget -qO- 'http://localhost:9090/api/v1/query?query=node_zfs_arcstats_size_bytes'
</pre>
<br />
<span>Check recording rules are calculating correctly:</span><br />
<br />
<pre>
kubectl exec -n monitoring prometheus-prometheus-kube-prometheus-prometheus-0 -c prometheus -- \
wget -qO- 'http://localhost:9090/api/v1/query?query=node_zfs_arc_memory_usage_percent'
</pre>
<br />
<span>Example output shows memory usage percentage for each FreeBSD server:</span><br />
<br />
<pre>
"result":[
{"metric":{"instance":"192.168.2.130:9100","os":"freebsd"},"value":[...,"37.58"]},
{"metric":{"instance":"192.168.2.131:9100","os":"freebsd"},"value":[...,"12.85"]},
{"metric":{"instance":"192.168.2.132:9100","os":"freebsd"},"value":[...,"13.44"]}
]
</pre>
<br />
<h3 style='display: inline' id='key-metrics-to-monitor'>Key Metrics to Monitor</h3><br />
<br />
<ul>
<li>ARC Hit Rate: Should typically be above 90% for optimal performance. Lower hit rates indicate the ARC cache is too small or workload has poor locality.</li>
<li>ARC Memory Usage: Shows how much of the maximum ARC size is being used. If consistently at or near maximum, the ARC is effectively utilizing available memory.</li>
<li>Data vs Metadata: Typically data should dominate, but workloads with many small files will show higher metadata percentages.</li>
<li>MRU vs MFU: Most Recently Used vs Most Frequently Used cache. The ratio depends on workload characteristics.</li>
<li>Pool Capacity: Monitor pool usage to ensure adequate free space. ZFS performance degrades when pools exceed 80% capacity.</li>
<li>Pool Health: Should always show ONLINE (green). DEGRADED (yellow) indicates a disk issue requiring attention. FAULTED (red) requires immediate action.</li>
<li>Dataset Usage: Track which datasets are consuming the most space to identify growth trends and plan capacity.</li>
</ul><br />
<h3 style='display: inline' id='zfs-pool-and-dataset-metrics-via-textfile-collector'>ZFS Pool and Dataset Metrics via Textfile Collector</h3><br />
<br />
<span>To complement the ARC statistics from node_exporter's built-in ZFS collector, I added pool capacity and dataset metrics using the textfile collector feature.</span><br />
<br />
<span>Created a script at <span class='inlinecode'>/usr/local/bin/zfs_pool_metrics.sh</span> on each FreeBSD server:</span><br />
<br />
<pre>
#!/bin/sh
# ZFS Pool and Dataset Metrics Collector for Prometheus
OUTPUT_FILE="/var/tmp/node_exporter/zfs_pools.prom.$$"
FINAL_FILE="/var/tmp/node_exporter/zfs_pools.prom"
mkdir -p /var/tmp/node_exporter
{
# Pool metrics
echo "# HELP zfs_pool_size_bytes Total size of ZFS pool"
echo "# TYPE zfs_pool_size_bytes gauge"
echo "# HELP zfs_pool_allocated_bytes Allocated space in ZFS pool"
echo "# TYPE zfs_pool_allocated_bytes gauge"
echo "# HELP zfs_pool_free_bytes Free space in ZFS pool"
echo "# TYPE zfs_pool_free_bytes gauge"
echo "# HELP zfs_pool_capacity_percent Capacity percentage"
echo "# TYPE zfs_pool_capacity_percent gauge"
echo "# HELP zfs_pool_health Pool health (0=ONLINE, 1=DEGRADED, 2=FAULTED)"
echo "# TYPE zfs_pool_health gauge"
zpool list -Hp -o name,size,allocated,free,capacity,health | \
while IFS=$'\t' read name size alloc free cap health; do
case "$health" in
ONLINE) health_val=0 ;;
DEGRADED) health_val=1 ;;
FAULTED) health_val=2 ;;
*) health_val=6 ;;
esac
cap_num=$(echo "$cap" | sed 's/%//')
echo "zfs_pool_size_bytes{pool=\"$name\"} $size"
echo "zfs_pool_allocated_bytes{pool=\"$name\"} $alloc"
echo "zfs_pool_free_bytes{pool=\"$name\"} $free"
echo "zfs_pool_capacity_percent{pool=\"$name\"} $cap_num"
echo "zfs_pool_health{pool=\"$name\"} $health_val"
done
# Dataset metrics
echo "# HELP zfs_dataset_used_bytes Used space in dataset"
echo "# TYPE zfs_dataset_used_bytes gauge"
echo "# HELP zfs_dataset_available_bytes Available space"
echo "# TYPE zfs_dataset_available_bytes gauge"
echo "# HELP zfs_dataset_referenced_bytes Referenced space"
echo "# TYPE zfs_dataset_referenced_bytes gauge"
zfs list -Hp -t filesystem -o name,used,available,referenced | \
while IFS=$'\t' read name used avail ref; do
pool=$(echo "$name" | cut -d/ -f1)
echo "zfs_dataset_used_bytes{pool=\"$pool\",dataset=\"$name\"} $used"
echo "zfs_dataset_available_bytes{pool=\"$pool\",dataset=\"$name\"} $avail"
echo "zfs_dataset_referenced_bytes{pool=\"$pool\",dataset=\"$name\"} $ref"
done
} > "$OUTPUT_FILE"
mv "$OUTPUT_FILE" "$FINAL_FILE"
</pre>
<br />
<span>Deployed to all FreeBSD servers:</span><br />
<br />
<pre>
for host in f0 f1 f2; do
scp /tmp/zfs_pool_metrics.sh paul@$host:/tmp/
ssh paul@$host 'doas mv /tmp/zfs_pool_metrics.sh /usr/local/bin/ && \
doas chmod +x /usr/local/bin/zfs_pool_metrics.sh'
done
</pre>
<br />
<span>Set up cron jobs to run every minute:</span><br />
<br />
<pre>
for host in f0 f1 f2; do
ssh paul@$host 'echo "* * * * * /usr/local/bin/zfs_pool_metrics.sh >/dev/null 2>&1" | \
doas crontab -'
done
</pre>
<br />
<span>The textfile collector (already configured with --collector.textfile.directory=/var/tmp/node_exporter) automatically picks up the metrics.</span><br />
<br />
<span>Verify metrics are being exposed:</span><br />
<br />
<pre>
paul@f0:~ % curl -s http://localhost:9100/metrics | grep "^zfs_pool" | head -5
zfs_pool_allocated_bytes{pool="zdata"} 6.47622733824e+11
zfs_pool_allocated_bytes{pool="zroot"} 5.3338578944e+10
zfs_pool_capacity_percent{pool="zdata"} 64
zfs_pool_capacity_percent{pool="zroot"} 10
zfs_pool_free_bytes{pool="zdata"} 3.48809678848e+11
</pre>
<br />
<span>All ZFS-related configuration files are available on Codeberg:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus/zfs-recording-rules.yaml'>zfs-recording-rules.yaml on Codeberg</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus/zfs-dashboards.yaml'>zfs-dashboards.yaml on Codeberg</a><br />
<br />
<h2 style='display: inline' id='monitoring-external-openbsd-hosts'>Monitoring external OpenBSD hosts</h2><br />
<br />
<span>The same approach works for OpenBSD hosts. I have two OpenBSD edge relay servers (<span class='inlinecode'>blowfish</span>, <span class='inlinecode'>fishfinger</span>) that handle TLS termination and forward traffic through WireGuard to the cluster. These can also be monitored with Node Exporter.</span><br />
<br />
<h3 style='display: inline' id='installing-node-exporter-on-openbsd'>Installing Node Exporter on OpenBSD</h3><br />
<br />
<span>On each OpenBSD host, install the node_exporter package:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">blowfish</font><font color="#F3E651">:~</font><font color="#ff0000"> $ doas pkg_add node_exporter</font>
<font color="#ff0000">quirks-</font><font color="#bb00ff">7.103</font><font color="#ff0000"> signed on </font><font color="#bb00ff">2025</font><font color="#ff0000">-</font><font color="#bb00ff">10</font><font color="#ff0000">-13T22</font><font color="#F3E651">:</font><font color="#bb00ff">55</font><font color="#F3E651">:</font><font color="#ff0000">16Z</font>
<font color="#ff0000">The following new rcscripts were installed</font><font color="#F3E651">:</font><font color="#ff0000"> /etc/rc</font><font color="#F3E651">.</font><font color="#ff0000">d/node_exporter</font>
<font color="#ff0000">See rcctl</font><font color="#F3E651">(</font><font color="#bb00ff">8</font><font color="#F3E651">)</font><font color="#ff0000"> </font><b><font color="#ffffff">for</font></b><font color="#ff0000"> details</font><font color="#F3E651">.</font>
</pre>
<br />
<span>Enable the service to start at boot:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">blowfish</font><font color="#F3E651">:~</font><font color="#ff0000"> $ doas rcctl </font><b><font color="#ffffff">enable</font></b><font color="#ff0000"> node_exporter</font>
</pre>
<br />
<span>Configure node_exporter to listen on the WireGuard interface. This ensures metrics are only accessible through the secure tunnel, not the public network. Replace the IP with the host's WireGuard address:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">blowfish</font><font color="#F3E651">:~</font><font color="#ff0000"> $ doas rcctl </font><b><font color="#ffffff">set</font></b><font color="#ff0000"> node_exporter flags </font><font color="#bb00ff">'--web.listen-address=192.168.2.110:9100'</font>
</pre>
<br />
<span>Start the service:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">blowfish</font><font color="#F3E651">:~</font><font color="#ff0000"> $ doas rcctl start node_exporter</font>
<font color="#ff0000">node_exporter</font><font color="#F3E651">(</font><font color="#ff0000">ok</font><font color="#F3E651">)</font>
</pre>
<br />
<span>Verify it's running:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ff0000">blowfish</font><font color="#F3E651">:~</font><font color="#ff0000"> $ curl -s http</font><font color="#F3E651">://</font><font color="#bb00ff">192.168</font><font color="#F3E651">.</font><font color="#bb00ff">2.110</font><font color="#F3E651">:</font><font color="#bb00ff">9100</font><font color="#ff0000">/metrics </font><font color="#F3E651">|</font><font color="#ff0000"> head -</font><font color="#bb00ff">3</font>
<i><font color="#ababab"># HELP go_gc_duration_seconds A summary of the wall-time pause...</font></i>
<i><font color="#ababab"># TYPE go_gc_duration_seconds summary</font></i>
<font color="#ff0000">go_gc_duration_seconds{</font><font color="#ff0000">quantile</font><font color="#F3E651">=</font><font color="#bb00ff">"0"</font><font color="#ff0000">} </font><font color="#bb00ff">0</font>
</pre>
<br />
<span>Repeat for the other OpenBSD host (<span class='inlinecode'>fishfinger</span>) with its respective WireGuard IP (<span class='inlinecode'>192.168.2.111</span>).</span><br />
<br />
<h3 style='display: inline' id='adding-openbsd-hosts-to-prometheus'>Adding OpenBSD hosts to Prometheus</h3><br />
<br />
<span>Update <span class='inlinecode'>additional-scrape-configs.yaml</span> to include the OpenBSD targets:</span><br />
<br />
<pre>
- job_name: 'node-exporter'
static_configs:
- targets:
- '192.168.2.130:9100' # f0 via WireGuard
- '192.168.2.131:9100' # f1 via WireGuard
- '192.168.2.132:9100' # f2 via WireGuard
labels:
os: freebsd
- targets:
- '192.168.2.110:9100' # blowfish via WireGuard
- '192.168.2.111:9100' # fishfinger via WireGuard
labels:
os: openbsd
</pre>
<br />
<span>The <span class='inlinecode'>os: openbsd</span> label allows filtering these hosts separately from FreeBSD and Linux nodes.</span><br />
<br />
<h3 style='display: inline' id='openbsd-memory-metrics-compatibility'>OpenBSD memory metrics compatibility</h3><br />
<br />
<span>OpenBSD uses the same memory metric names as FreeBSD (<span class='inlinecode'>node_memory_size_bytes</span>, <span class='inlinecode'>node_memory_free_bytes</span>, etc.), so a similar PrometheusRule is needed to generate Linux-compatible metrics:</span><br />
<br />
<pre>
apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
name: openbsd-memory-rules
namespace: monitoring
labels:
release: prometheus
spec:
groups:
- name: openbsd-memory
rules:
- record: node_memory_MemTotal_bytes
expr: node_memory_size_bytes{os="openbsd"}
labels:
os: openbsd
- record: node_memory_MemAvailable_bytes
expr: |
node_memory_free_bytes{os="openbsd"}
+ node_memory_inactive_bytes{os="openbsd"}
+ node_memory_cache_bytes{os="openbsd"}
labels:
os: openbsd
- record: node_memory_MemFree_bytes
expr: node_memory_free_bytes{os="openbsd"}
labels:
os: openbsd
- record: node_memory_Cached_bytes
expr: node_memory_cache_bytes{os="openbsd"}
labels:
os: openbsd
</pre>
<br />
<span>This file is saved as <span class='inlinecode'>openbsd-recording-rules.yaml</span> and applied alongside the FreeBSD rules. Note that OpenBSD doesn't expose a buffer memory metric, so that rule is omitted.</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus/openbsd-recording-rules.yaml'>openbsd-recording-rules.yaml on Codeberg</a><br />
<br />
<span>After running <span class='inlinecode'>just upgrade</span>, the OpenBSD hosts appear in Prometheus targets and the Node Exporter dashboards.</span><br />
<br />
<h2 style='display: inline' id='distributed-tracing-with-grafana-tempo'>Distributed Tracing with Grafana Tempo</h2><br />
<br />
<span>After implementing logs (Loki) and metrics (Prometheus), the final pillar of observability is distributed tracing. Grafana Tempo provides distributed tracing capabilities that help understand request flows across microservices.</span><br />
<br />
<span>For a preview of what distributed tracing with Tempo looks like in Grafana, see the X-RAG blog post:</span><br />
<br />
<a class='textlink' href='./2025-12-24-x-rag-observability-hackathon.html'>X-RAG Observability Hackathon</a><br />
<br />
<h3 style='display: inline' id='why-distributed-tracing'>Why Distributed Tracing?</h3><br />
<br />
<span>In a microservices architecture, a single user request may traverse multiple services. Distributed tracing:</span><br />
<br />
<ul>
<li>Tracks requests across service boundaries</li>
<li>Identifies performance bottlenecks</li>
<li>Visualizes service dependencies</li>
<li>Correlates with logs and metrics</li>
<li>Helps debug complex distributed systems</li>
</ul><br />
<h3 style='display: inline' id='deploying-grafana-tempo'>Deploying Grafana Tempo</h3><br />
<br />
<span>Tempo is deployed in monolithic mode, following the same pattern as Loki's SingleBinary deployment.</span><br />
<br />
<span>#### Configuration Strategy</span><br />
<br />
<span>**Deployment Mode:** Monolithic (all components in one process)</span><br />
<ul>
<li>Simpler operation than microservices mode</li>
<li>Suitable for the cluster scale</li>
<li>Consistent with Loki deployment pattern</li>
</ul><br />
<span>**Storage:** Filesystem backend using hostPath</span><br />
<ul>
<li>10Gi storage at /data/nfs/k3svolumes/tempo/data</li>
<li>7-day retention (168h)</li>
<li>Local storage is the only option for monolithic mode</li>
</ul><br />
<span>**OTLP Receivers:** Standard OpenTelemetry Protocol ports</span><br />
<ul>
<li>gRPC: 4317</li>
<li>HTTP: 4318</li>
<li>Bind to 0.0.0.0 to avoid Tempo 2.7+ localhost-only binding issue</li>
</ul><br />
<span>#### Tempo Deployment Files</span><br />
<br />
<span>Created in /home/paul/git/conf/f3s/tempo/:</span><br />
<br />
<span>**values.yaml** - Helm chart configuration:</span><br />
<br />
<pre>
tempo:
retention: 168h
storage:
trace:
backend: local
local:
path: /var/tempo/traces
wal:
path: /var/tempo/wal
receivers:
otlp:
protocols:
grpc:
endpoint: 0.0.0.0:4317
http:
endpoint: 0.0.0.0:4318
persistence:
enabled: true
size: 10Gi
storageClassName: ""
resources:
limits:
cpu: 1000m
memory: 2Gi
requests:
cpu: 500m
memory: 1Gi
</pre>
<br />
<span>**persistent-volumes.yaml** - Storage configuration:</span><br />
<br />
<pre>
apiVersion: v1
kind: PersistentVolume
metadata:
name: tempo-data-pv
spec:
capacity:
storage: 10Gi
accessModes:
- ReadWriteOnce
persistentVolumeReclaimPolicy: Retain
hostPath:
path: /data/nfs/k3svolumes/tempo/data
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
name: tempo-data-pvc
namespace: monitoring
spec:
storageClassName: ""
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
</pre>
<br />
<span>**Grafana Datasource Provisioning**</span><br />
<br />
<span>All Grafana datasources (Prometheus, Alertmanager, Loki, Tempo) are provisioned via a unified ConfigMap that is directly mounted to the Grafana pod. This approach ensures datasources are loaded on startup without requiring sidecar-based discovery.</span><br />
<br />
<span>In /home/paul/git/conf/f3s/prometheus/grafana-datasources-all.yaml:</span><br />
<br />
<pre>
apiVersion: v1
kind: ConfigMap
metadata:
name: grafana-datasources-all
namespace: monitoring
data:
datasources.yaml: |
apiVersion: 1
datasources:
- name: Prometheus
type: prometheus
uid: prometheus
url: http://prometheus-kube-prometheus-prometheus.monitoring:9090/
access: proxy
isDefault: true
- name: Alertmanager
type: alertmanager
uid: alertmanager
url: http://prometheus-kube-prometheus-alertmanager.monitoring:9093/
- name: Loki
type: loki
uid: loki
url: http://loki.monitoring.svc.cluster.local:3100
- name: Tempo
type: tempo
uid: tempo
url: http://tempo.monitoring.svc.cluster.local:3200
jsonData:
tracesToLogsV2:
datasourceUid: loki
spanStartTimeShift: -1h
spanEndTimeShift: 1h
tracesToMetrics:
datasourceUid: prometheus
serviceMap:
datasourceUid: prometheus
nodeGraph:
enabled: true
</pre>
<br />
<span>The kube-prometheus-stack Helm values (persistence-values.yaml) are configured to:</span><br />
<ul>
<li>Disable sidecar-based datasource provisioning</li>
<li>Mount grafana-datasources-all ConfigMap directly to /etc/grafana/provisioning/datasources/</li>
</ul><br />
<span>This direct mounting approach is simpler and more reliable than sidecar-based discovery.</span><br />
<br />
<span>#### Installation</span><br />
<br />
<pre>
cd /home/paul/git/conf/f3s/tempo
just install
</pre>
<br />
<span>Verify Tempo is running:</span><br />
<br />
<pre>
kubectl get pods -n monitoring -l app.kubernetes.io/name=tempo
kubectl exec -n monitoring <tempo-pod> -- wget -qO- http://localhost:3200/ready
</pre>
<br />
<h3 style='display: inline' id='configuring-grafana-alloy-for-trace-collection'>Configuring Grafana Alloy for Trace Collection</h3><br />
<br />
<span>Updated /home/paul/git/conf/f3s/loki/alloy-values.yaml to add OTLP receivers for traces while maintaining existing log collection.</span><br />
<br />
<span>#### OTLP Receiver Configuration</span><br />
<br />
<span>Added to Alloy configuration after the log collection pipeline:</span><br />
<br />
<pre>
// OTLP receiver for traces via gRPC and HTTP
otelcol.receiver.otlp "default" {
grpc {
endpoint = "0.0.0.0:4317"
}
http {
endpoint = "0.0.0.0:4318"
}
output {
traces = [otelcol.processor.batch.default.input]
}
}
// Batch processor for efficient trace forwarding
otelcol.processor.batch "default" {
timeout = "5s"
send_batch_size = 100
send_batch_max_size = 200
output {
traces = [otelcol.exporter.otlp.tempo.input]
}
}
// OTLP exporter to send traces to Tempo
otelcol.exporter.otlp "tempo" {
client {
endpoint = "tempo.monitoring.svc.cluster.local:4317"
tls {
insecure = true
}
compression = "gzip"
}
}
</pre>
<br />
<span>The batch processor reduces network overhead by accumulating spans before forwarding to Tempo.</span><br />
<br />
<span>#### Upgrade Alloy</span><br />
<br />
<pre>
cd /home/paul/git/conf/f3s/loki
just upgrade
</pre>
<br />
<span>Verify OTLP receivers are listening:</span><br />
<br />
<pre>
kubectl logs -n monitoring -l app.kubernetes.io/name=alloy | grep -i "otlp.*receiver"
kubectl exec -n monitoring <alloy-pod> -- netstat -ln | grep -E ':(4317|4318)'
</pre>
<br />
<h3 style='display: inline' id='demo-tracing-application'>Demo Tracing Application</h3><br />
<br />
<span>Created a three-tier Python application to demonstrate distributed tracing in action.</span><br />
<br />
<span>#### Application Architecture</span><br />
<br />
<pre>
User → Frontend (Flask:5000) → Middleware (Flask:5001) → Backend (Flask:5002)
↓ ↓ ↓
Alloy (OTLP:4317) → Tempo → Grafana
</pre>
<br />
<span>Frontend Service:</span><br />
<br />
<ul>
<li>Receives HTTP requests at /api/process</li>
<li>Forwards to middleware service</li>
<li>Creates parent span for the entire request</li>
</ul><br />
<span>Middleware Service:</span><br />
<br />
<ul>
<li>Transforms data at /api/transform</li>
<li>Calls backend service</li>
<li>Creates child span linked to frontend</li>
</ul><br />
<span>Backend Service:</span><br />
<br />
<ul>
<li>Returns data at /api/data</li>
<li>Simulates database query (100ms sleep)</li>
<li>Creates leaf span in the trace</li>
</ul><br />
<span>OpenTelemetry Instrumentation:</span><br />
<br />
<span>All services use Python OpenTelemetry libraries:</span><br />
<br />
<span>**Dependencies:**</span><br />
<pre>
flask==3.0.0
requests==2.31.0
opentelemetry-distro==0.49b0
opentelemetry-exporter-otlp==1.28.0
opentelemetry-instrumentation-flask==0.49b0
opentelemetry-instrumentation-requests==0.49b0
</pre>
<br />
<span>**Auto-instrumentation pattern** (used in all services):</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#ababab">from</font><font color="#ff0000"> opentelemetry </font><font color="#ababab">import</font><font color="#ff0000"> trace</font>
<font color="#ababab">from</font><font color="#ff0000"> opentelemetry</font><font color="#F3E651">.</font><font color="#ff0000">sdk</font><font color="#F3E651">.</font><font color="#ff0000">trace </font><font color="#ababab">import</font><font color="#ff0000"> TracerProvider</font>
<font color="#ababab">from</font><font color="#ff0000"> opentelemetry</font><font color="#F3E651">.</font><font color="#ff0000">exporter</font><font color="#F3E651">.</font><font color="#ff0000">otlp</font><font color="#F3E651">.</font><font color="#ff0000">proto</font><font color="#F3E651">.</font><font color="#ff0000">grpc</font><font color="#F3E651">.</font><font color="#ff0000">trace_exporter </font><font color="#ababab">import</font><font color="#ff0000"> OTLPSpanExporter</font>
<font color="#ababab">from</font><font color="#ff0000"> opentelemetry</font><font color="#F3E651">.</font><font color="#ff0000">instrumentation</font><font color="#F3E651">.</font><font color="#ff0000">flask </font><font color="#ababab">import</font><font color="#ff0000"> FlaskInstrumentor</font>
<font color="#ababab">from</font><font color="#ff0000"> opentelemetry</font><font color="#F3E651">.</font><font color="#ff0000">instrumentation</font><font color="#F3E651">.</font><font color="#ff0000">requests </font><font color="#ababab">import</font><font color="#ff0000"> RequestsInstrumentor</font>
<font color="#ababab">from</font><font color="#ff0000"> opentelemetry</font><font color="#F3E651">.</font><font color="#ff0000">sdk</font><font color="#F3E651">.</font><font color="#ff0000">resources </font><font color="#ababab">import</font><font color="#ff0000"> Resource</font>
<i><font color="#ababab"># Define service identity</font></i>
<font color="#ff0000">resource </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#7bc710">Resource</font><font color="#F3E651">(</font><font color="#ff0000">attributes</font><font color="#F3E651">={</font>
<font color="#ff0000"> </font><font color="#bb00ff">"service.name"</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#bb00ff">"frontend"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#bb00ff">"service.namespace"</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#bb00ff">"tracing-demo"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#bb00ff">"service.version"</font><font color="#F3E651">:</font><font color="#ff0000"> </font><font color="#bb00ff">"1.0.0"</font>
<font color="#F3E651">})</font>
<font color="#ff0000">provider </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#7bc710">TracerProvider</font><font color="#F3E651">(</font><font color="#ff0000">resource</font><font color="#F3E651">=</font><font color="#ff0000">resource</font><font color="#F3E651">)</font>
<i><font color="#ababab"># Export to Alloy</font></i>
<font color="#ff0000">otlp_exporter </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#7bc710">OTLPSpanExporter</font><font color="#F3E651">(</font>
<font color="#ff0000"> endpoint</font><font color="#F3E651">=</font><font color="#bb00ff">"http://alloy.monitoring.svc.cluster.local:4317"</font><font color="#F3E651">,</font>
<font color="#ff0000"> insecure</font><font color="#F3E651">=</font><font color="#ff0000">True</font>
<font color="#F3E651">)</font>
<font color="#ff0000">processor </font><font color="#F3E651">=</font><font color="#ff0000"> </font><font color="#7bc710">BatchSpanProcessor</font><font color="#F3E651">(</font><font color="#ff0000">otlp_exporter</font><font color="#F3E651">)</font>
<font color="#ff0000">provider</font><font color="#F3E651">.</font><font color="#7bc710">add_span_processor</font><font color="#F3E651">(</font><font color="#ff0000">processor</font><font color="#F3E651">)</font>
<font color="#ff0000">trace</font><font color="#F3E651">.</font><font color="#7bc710">set_tracer_provider</font><font color="#F3E651">(</font><font color="#ff0000">provider</font><font color="#F3E651">)</font>
<i><font color="#ababab"># Auto-instrument Flask and requests</font></i>
<font color="#7bc710">FlaskInstrumentor</font><font color="#F3E651">().</font><font color="#7bc710">instrument_app</font><font color="#F3E651">(</font><font color="#ff0000">app</font><font color="#F3E651">)</font>
<font color="#7bc710">RequestsInstrumentor</font><font color="#F3E651">().</font><font color="#7bc710">instrument</font><font color="#F3E651">()</font>
</pre>
<br />
<span>The auto-instrumentation automatically:</span><br />
<ul>
<li>Creates spans for HTTP requests</li>
<li>Propagates trace context via W3C Trace Context headers</li>
<li>Links parent and child spans across service boundaries</li>
</ul><br />
<span>Deployment:</span><br />
<br />
<span>Created Helm chart in /home/paul/git/conf/f3s/tracing-demo/ with three separate deployments, services, and an ingress.</span><br />
<br />
<span>Build and deploy:</span><br />
<br />
<pre>
cd /home/paul/git/conf/f3s/tracing-demo
just build
just import
just install
</pre>
<br />
<span>Verify deployment:</span><br />
<br />
<pre>
kubectl get pods -n services | grep tracing-demo
kubectl get ingress -n services tracing-demo-ingress
</pre>
<br />
<span>Access the application at:</span><br />
<br />
<a class='textlink' href='http://tracing-demo.f3s.buetow.org'>http://tracing-demo.f3s.buetow.org</a><br />
<br />
<h3 style='display: inline' id='visualizing-traces-in-grafana'>Visualizing Traces in Grafana</h3><br />
<br />
<span>The Tempo datasource is automatically discovered by Grafana through the ConfigMap label.</span><br />
<br />
<span>#### Accessing Traces</span><br />
<br />
<span>Navigate to Grafana → Explore → Select "Tempo" datasource</span><br />
<br />
<span>**Search Interface:**</span><br />
<ul>
<li>Search by Trace ID</li>
<li>Search by service name</li>
<li>Search by tags</li>
</ul><br />
<span>**TraceQL Queries:**</span><br />
<br />
<span>Find all traces from demo app:</span><br />
<pre>
{ resource.service.namespace = "tracing-demo" }
</pre>
<br />
<span>Find slow requests (>200ms):</span><br />
<pre>
{ duration > 200ms }
</pre>
<br />
<span>Find traces from specific service:</span><br />
<pre>
{ resource.service.name = "frontend" }
</pre>
<br />
<span>Find errors:</span><br />
<pre>
{ status = error }
</pre>
<br />
<span>Complex query - frontend traces calling middleware:</span><br />
<pre>
{ resource.service.namespace = "tracing-demo" } && { span.http.status_code >= 500 }
</pre>
<br />
<span>#### Service Graph Visualization</span><br />
<br />
<span>The service graph shows visual connections between services:</span><br />
<br />
<span>1. Navigate to Explore → Tempo</span><br />
<span>2. Enable "Service Graph" view</span><br />
<span>3. Shows: Frontend → Middleware → Backend with request rates</span><br />
<br />
<span>The service graph uses Prometheus metrics generated from trace data.</span><br />
<br />
<h3 style='display: inline' id='correlation-between-observability-signals'>Correlation Between Observability Signals</h3><br />
<br />
<span>Tempo integrates with Loki and Prometheus to provide unified observability.</span><br />
<br />
<span>#### Traces-to-Logs</span><br />
<br />
<span>Click on any span in a trace to see related logs:</span><br />
<br />
<span>1. View trace in Grafana</span><br />
<span>2. Click on a span</span><br />
<span>3. Select "Logs for this span"</span><br />
<span>4. Loki shows logs filtered by:</span><br />
<span> * Time range (span duration ± 1 hour)</span><br />
<span> * Service name</span><br />
<span> * Namespace</span><br />
<span> * Pod</span><br />
<br />
<span>This helps correlate what the service was doing when the span was created.</span><br />
<br />
<span>#### Traces-to-Metrics</span><br />
<br />
<span>View Prometheus metrics for services in the trace:</span><br />
<br />
<span>1. View trace in Grafana</span><br />
<span>2. Select "Metrics" tab</span><br />
<span>3. Shows metrics like:</span><br />
<span> * Request rate</span><br />
<span> * Error rate</span><br />
<span> * Duration percentiles</span><br />
<br />
<span>#### Logs-to-Traces</span><br />
<br />
<span>From logs, you can jump to related traces:</span><br />
<br />
<span>1. In Loki, logs that contain trace IDs are automatically linked</span><br />
<span>2. Click the trace ID to view the full trace</span><br />
<span>3. See the complete request flow</span><br />
<br />
<h3 style='display: inline' id='generating-traces-for-testing'>Generating Traces for Testing</h3><br />
<br />
<span>Test the demo application:</span><br />
<br />
<pre>
curl http://tracing-demo.f3s.buetow.org/api/process
</pre>
<br />
<span>Load test (generates 50 traces):</span><br />
<br />
<pre>
cd /home/paul/git/conf/f3s/tracing-demo
just load-test
</pre>
<br />
<span>Each request creates a distributed trace spanning all three services.</span><br />
<br />
<h3 style='display: inline' id='verifying-the-complete-pipeline'>Verifying the Complete Pipeline</h3><br />
<br />
<span>Check the trace flow end-to-end:</span><br />
<br />
<span>**1. Application generates traces:**</span><br />
<pre>
kubectl logs -n services -l app=tracing-demo-frontend | grep -i trace
</pre>
<br />
<span>**2. Alloy receives traces:**</span><br />
<pre>
kubectl logs -n monitoring -l app.kubernetes.io/name=alloy | grep -i otlp
</pre>
<br />
<span>**3. Tempo stores traces:**</span><br />
<pre>
kubectl logs -n monitoring -l app.kubernetes.io/name=tempo | grep -i trace
</pre>
<br />
<span>**4. Grafana displays traces:**</span><br />
<span>Navigate to Explore → Tempo → Search for traces</span><br />
<br />
<h3 style='display: inline' id='practical-example-viewing-a-distributed-trace'>Practical Example: Viewing a Distributed Trace</h3><br />
<br />
<span>Let's generate a trace and examine it in Grafana.</span><br />
<br />
<span>**1. Generate a trace by calling the demo application:**</span><br />
<br />
<pre>
curl -H "Host: tracing-demo.f3s.buetow.org" http://r0/api/process
</pre>
<br />
<span>**Response (HTTP 200):**</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">middleware_response</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">backend_data</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">data</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">id</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#bb00ff">12345</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">query_time_ms</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#bb00ff">100.0</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">timestamp</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">2025-12-28T18:35:01.064538</font><font color="#ff0000">"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">value</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">Sample data from backend service</font><font color="#ff0000">"</font>
<font color="#ff0000"> </font><font color="#F3E651">},</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">service</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">backend</font><font color="#ff0000">"</font>
<font color="#ff0000"> </font><font color="#F3E651">},</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">middleware_processed</font><font color="#ff0000">"</font><font color="#ff0000">: </font><b><font color="#ffffff">true</font></b><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">original_data</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">source</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">GET request</font><font color="#ff0000">"</font>
<font color="#ff0000"> </font><font color="#F3E651">},</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">transformation_time_ms</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#bb00ff">50</font>
<font color="#ff0000"> </font><font color="#F3E651">},</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">request_data</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">source</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">GET request</font><font color="#ff0000">"</font>
<font color="#ff0000"> </font><font color="#F3E651">},</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">service</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">frontend</font><font color="#ff0000">"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">status</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">success</font><font color="#ff0000">"</font>
<font color="#F3E651">}</font>
</pre>
<br />
<span>**2. Find the trace in Tempo via API:**</span><br />
<br />
<span>After a few seconds (for batch export), search for recent traces:</span><br />
<br />
<pre>
kubectl exec -n monitoring tempo-0 -- wget -qO- \
'http://localhost:3200/api/search?tags=service.namespace%3Dtracing-demo&limit=5' 2>/dev/null | \
python3 -m json.tool
</pre>
<br />
<span>Returns traces including:</span><br />
<br />
<!-- Generator: GNU source-highlight 3.1.9
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite -->
<pre><font color="#F3E651">{</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">traceID</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">4be1151c0bdcd5625ac7e02b98d95bd5</font><font color="#ff0000">"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">rootServiceName</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">frontend</font><font color="#ff0000">"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">rootTraceName</font><font color="#ff0000">"</font><font color="#ff0000">:</font><font color="#ff0000"> "</font><font color="#bb00ff">GET /api/process</font><font color="#ff0000">"</font><font color="#F3E651">,</font>
<font color="#ff0000"> </font><font color="#ff0000">"</font><font color="#ff0000">durationMs</font><font color="#ff0000">"</font><font color="#ff0000">: </font><font color="#bb00ff">221</font>
<font color="#F3E651">}</font>
</pre>
<br />
<span>**3. Fetch complete trace details:**</span><br />
<br />
<pre>
kubectl exec -n monitoring tempo-0 -- wget -qO- \
'http://localhost:3200/api/traces/4be1151c0bdcd5625ac7e02b98d95bd5' 2>/dev/null | \
python3 -m json.tool
</pre>
<br />
<span>**Trace structure (8 spans across 3 services):**</span><br />
<br />
<pre>
Trace ID: 4be1151c0bdcd5625ac7e02b98d95bd5
Services: 3 (frontend, middleware, backend)
Service: frontend
└─ GET /api/process 221.10ms (HTTP server span)
└─ frontend-process 216.23ms (custom business logic span)
└─ POST 209.97ms (HTTP client span to middleware)
Service: middleware
└─ POST /api/transform 186.02ms (HTTP server span)
└─ middleware-transform 180.96ms (custom business logic span)
└─ GET 127.52ms (HTTP client span to backend)
Service: backend
└─ GET /api/data 103.93ms (HTTP server span)
└─ backend-get-data 102.11ms (custom business logic span with 100ms sleep)
</pre>
<br />
<span>**4. View the trace in Grafana UI:**</span><br />
<br />
<span>Navigate to: Grafana → Explore → Tempo datasource</span><br />
<br />
<span>Search using TraceQL:</span><br />
<pre>
{ resource.service.namespace = "tracing-demo" }
</pre>
<br />
<span>Or directly open the trace by pasting the trace ID in the search box:</span><br />
<pre>
4be1151c0bdcd5625ac7e02b98d95bd5
</pre>
<br />
<span>**5. Trace visualization:**</span><br />
<br />
<span>The trace waterfall view in Grafana shows the complete request flow with timing:</span><br />
<br />
<a href='./f3s-kubernetes-with-freebsd-part-8/grafana-tempo-trace.png'><img alt='Distributed trace visualization in Grafana Tempo showing Frontend → Middleware → Backend spans' title='Distributed trace visualization in Grafana Tempo showing Frontend → Middleware → Backend spans' src='./f3s-kubernetes-with-freebsd-part-8/grafana-tempo-trace.png' /></a><br />
<br />
<span>For additional examples of Tempo trace visualization, see also:</span><br />
<br />
<a class='textlink' href='https://foo.zone/gemfeed/2025-12-24-x-rag-observability-hackathon.html'>X-RAG Observability Hackathon (more Grafana Tempo screenshots)</a><br />
<br />
<span>The trace reveals the distributed request flow:</span><br />
<br />
<ul>
<li>Frontend (221ms): Receives GET /api/process, executes business logic, calls middleware</li>
<li>Middleware (186ms): Receives POST /api/transform, transforms data, calls backend</li>
<li>Backend (104ms): Receives GET /api/data, simulates database query with 100ms sleep</li>
<li>Total request time: 221ms end-to-end</li>
<li>Span propagation: W3C Trace Context headers automatically link all spans</li>
</ul><br />
<span>**6. Service graph visualization:**</span><br />
<br />
<span>The service graph is automatically generated from traces and shows service dependencies. For examples of service graph visualization in Grafana, see the screenshots in the X-RAG Observability Hackathon blog post.</span><br />
<br />
<a class='textlink' href='./2025-12-24-x-rag-observability-hackathon.html'>X-RAG Observability Hackathon (includes service graph screenshots)</a><br />
<br />
<span>This visualization helps identify:</span><br />
<br />
<ul>
<li>Request rates between services</li>
<li>Average latency for each hop</li>
<li>Error rates (if any)</li>
<li>Service dependencies and communication patterns</li>
</ul><br />
<h3 style='display: inline' id='storage-and-retention'>Storage and Retention</h3><br />
<br />
<span>Monitor Tempo storage usage:</span><br />
<br />
<pre>
kubectl exec -n monitoring <tempo-pod> -- df -h /var/tempo
</pre>
<br />
<span>With 10Gi storage and 7-day retention, the system handles moderate trace volumes. If storage fills up:</span><br />
<br />
<ul>
<li>Reduce retention to 72h (3 days)</li>
<li>Implement sampling in Alloy</li>
<li>Increase PV size</li>
</ul><br />
<h3 style='display: inline' id='configuration-files'>Configuration Files</h3><br />
<br />
<span>All configuration files are available on Codeberg:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/tempo'>Tempo configuration</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/loki'>Alloy configuration (updated for traces)</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/tracing-demo'>Demo tracing application</a><br />
<br />
<h2 style='display: inline' id='summary'>Summary</h2><br />
<br />
<span>With Prometheus, Grafana, Loki, Alloy, and Tempo deployed, I now have complete visibility into the k3s cluster, the FreeBSD storage servers, and the OpenBSD edge relays:</span><br />
<br />
<ul>
<li>Metrics: Prometheus collects and stores time-series data from all components, including etcd and ZFS</li>
<li>Logs: Loki aggregates logs from all containers, searchable via Grafana</li>
<li>Traces: Tempo provides distributed request tracing with service dependency mapping</li>
<li>Visualisation: Grafana provides dashboards and exploration tools with correlation between all three signals</li>
<li>Alerting: Alertmanager can notify on conditions defined in Prometheus rules</li>
</ul><br />
<span>This observability stack runs entirely on the home lab infrastructure, with data persisted to the NFS share. It's lightweight enough for a three-node cluster but provides the same capabilities as production-grade setups.</span><br />
<br />
<span>All configuration files are available on Codeberg:</span><br />
<br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/prometheus'>Prometheus, Grafana, and recording rules configuration</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/loki'>Loki and Alloy configuration</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/tempo'>Tempo configuration</a><br />
<a class='textlink' href='https://codeberg.org/snonux/conf/src/branch/master/f3s/tracing-demo'>Demo tracing application</a><br />
<br />
<span>Other *BSD-related posts:</span><br />
<br />
<a class='textlink' href='./2025-12-07-f3s-kubernetes-with-freebsd-part-8.html'>2025-12-07 f3s: Kubernetes with FreeBSD - Part 8: Observability (You are currently reading this)</a><br />
<a class='textlink' href='./2025-10-02-f3s-kubernetes-with-freebsd-part-7.html'>2025-10-02 f3s: Kubernetes with FreeBSD - Part 7: k3s and first pod deployments</a><br />
<a class='textlink' href='./2025-07-14-f3s-kubernetes-with-freebsd-part-6.html'>2025-07-14 f3s: Kubernetes with FreeBSD - Part 6: Storage</a><br />
<a class='textlink' href='./2025-05-11-f3s-kubernetes-with-freebsd-part-5.html'>2025-05-11 f3s: Kubernetes with FreeBSD - Part 5: WireGuard mesh network</a><br />
<a class='textlink' href='./2025-04-05-f3s-kubernetes-with-freebsd-part-4.html'>2025-04-05 f3s: Kubernetes with FreeBSD - Part 4: Rocky Linux Bhyve VMs</a><br />
<a class='textlink' href='./2025-02-01-f3s-kubernetes-with-freebsd-part-3.html'>2025-02-01 f3s: Kubernetes with FreeBSD - Part 3: Protecting from power cuts</a><br />
<a class='textlink' href='./2024-12-03-f3s-kubernetes-with-freebsd-part-2.html'>2024-12-03 f3s: Kubernetes with FreeBSD - Part 2: Hardware and base installation</a><br />
<a class='textlink' href='./2024-11-17-f3s-kubernetes-with-freebsd-part-1.html'>2024-11-17 f3s: Kubernetes with FreeBSD - Part 1: Setting the stage</a><br />
<a class='textlink' href='./2024-04-01-KISS-high-availability-with-OpenBSD.html'>2024-04-01 KISS high-availability with OpenBSD</a><br />
<a class='textlink' href='./2024-01-13-one-reason-why-i-love-openbsd.html'>2024-01-13 One reason why I love OpenBSD</a><br />
<a class='textlink' href='./2022-10-30-installing-dtail-on-openbsd.html'>2022-10-30 Installing DTail on OpenBSD</a><br />
<a class='textlink' href='./2022-07-30-lets-encrypt-with-openbsd-and-rex.html'>2022-07-30 Let's Encrypt with OpenBSD and Rex</a><br />
<a class='textlink' href='./2016-04-09-jails-and-zfs-on-freebsd-with-puppet.html'>2016-04-09 Jails and ZFS with Puppet on FreeBSD</a><br />
<br />
<span>E-Mail your comments to <span class='inlinecode'>paul@nospam.buetow.org</span></span><br />
<br />
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