3 files changed, 102 insertions, 2 deletions

diff --git a/cmd/snonux/main.go b/cmd/snonux/main.go
index 1d00646..42a377f 100644
--- a/cmd/snonux/main.go
+++ b/cmd/snonux/main.go
@@ -4,7 +4,7 @@
 //
 // Usage:
 //
-//	snonux --input ./inbox --output ./outdir [--base-url https://snonux.foo]
+//	snonux [--input ./inbox] [--output ./dist] [--base-url https://snonux.foo]
 package main
 
 import (
@@ -51,6 +51,12 @@ func main() {
 	if err := run(cfg); err != nil {
 		log.Fatalf("error: %v", err)
 	}
+
+	if cfg.Sync {
+		if err := syncOutput(cfg.OutputDir); err != nil {
+			log.Fatalf("error: %v", err)
+		}
+	}
 }
 
 // errParseFlags is returned when flag parsing fails (e.g. unknown flag).
@@ -69,9 +75,10 @@ func parseFlags(args []string) (*config.Config, cliMode, error) {
 	listThemes := fs.Bool("list-themes", false, "print all available theme names and exit")
 
 	fs.StringVar(&cfg.InputDir, "input", "./inbox", "directory containing new source files to process")
-	fs.StringVar(&cfg.OutputDir, "output", "~/git/snonux.foo/dist", "root directory for generated static site output")
+	fs.StringVar(&cfg.OutputDir, "output", "./dist", "root directory for generated static site output")
 	fs.StringVar(&cfg.BaseURL, "base-url", "https://snonux.foo", "canonical base URL used in Atom feed links")
 	fs.StringVar(&cfg.Theme, "theme", "random", "visual theme name, or \"random\" to pick one at random")
+	fs.BoolVar(&cfg.Sync, "sync", false, "after a successful run, rsync -output to pi0/pi1 when both are pingable (SSH user: SNONUX_SYNC_USER or login name)")
 
 	if err := fs.Parse(args); err != nil {
 		return nil, modeRun, fmt.Errorf("%w: %w", errParseFlags, err)
diff --git a/cmd/snonux/main_test.go b/cmd/snonux/main_test.go
index 212efc8..7f05c8b 100644
--- a/cmd/snonux/main_test.go
+++ b/cmd/snonux/main_test.go
@@ -104,6 +104,28 @@ func TestParseFlags_run(t *testing.T) {
 	}
 }
 
+func TestParseFlags_sync(t *testing.T) {
+	t.Parallel()
+
+	in := t.TempDir()
+	out := t.TempDir()
+	cfg, mode, err := parseFlags([]string{
+		"-input", in,
+		"-output", out,
+		"-theme", "neon",
+		"-sync",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if mode != modeRun {
+		t.Fatalf("mode %v", mode)
+	}
+	if !cfg.Sync {
+		t.Fatal("expected cfg.Sync")
+	}
+}
+
 func TestParseFlags_randomTheme(t *testing.T) {
 	t.Parallel()
 
diff --git a/cmd/snonux/sync.go b/cmd/snonux/sync.go
new file mode 100644
index 0000000..46993e2
--- /dev/null
+++ b/cmd/snonux/sync.go
@@ -0,0 +1,71 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"os/exec"
+	"os/user"
+	"path/filepath"
+	"time"
+)
+
+// SNONUX_SYNC_USER overrides the SSH username for rsync (default: current login name).
+const envSyncUser = "SNONUX_SYNC_USER"
+
+var syncTargets = []string{
+	"pi0.lan.buetow.org",
+	"pi1.lan.buetow.org",
+}
+
+const syncRemoteDir = "/var/www/html/snonux/"
+
+// syncOutput rsyncs localOutput (trailing-slash source) to each sync target over SSH
+// port 22. It runs only if every target answers ICMP ping (Linux iputils: ping -c 1 -W …).
+func syncOutput(localOutput string) error {
+	for _, host := range syncTargets {
+		if !hostPingable(host) {
+			log.Printf("sync skipped: %q not pingable (all mirror hosts must be reachable)", host)
+			return nil
+		}
+	}
+
+	sshUser := os.Getenv(envSyncUser)
+	if sshUser == "" {
+		u, err := user.Current()
+		if err != nil {
+			return fmt.Errorf("sync user: %w (set %s)", err, envSyncUser)
+		}
+		sshUser = u.Username
+	}
+
+	absOut, err := filepath.Abs(localOutput)
+	if err != nil {
+		return fmt.Errorf("sync output dir: %w", err)
+	}
+	src := filepath.Clean(absOut) + string(filepath.Separator)
+
+	ssh := "ssh -p 22 -o BatchMode=yes -o ConnectTimeout=15"
+	for _, host := range syncTargets {
+		dest := fmt.Sprintf("%s@%s:%s", sshUser, host, syncRemoteDir)
+		log.Printf("rsync %s -> %s", src, dest)
+		cmd := exec.Command("rsync", "-az", "-e", ssh, src, dest)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			return fmt.Errorf("rsync to %s: %w", host, err)
+		}
+	}
+	return nil
+}
+
+func hostPingable(host string) bool {
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+	// Linux iputils-ping: -c 1 one packet, -W 3 wait up to 3s for reply.
+	cmd := exec.CommandContext(ctx, "ping", "-c", "1", "-W", "3", host)
+	cmd.Stdout = nil
+	cmd.Stderr = nil
+	return cmd.Run() == nil
+}