feat(entrypoint): Implement TTL heartbeat registration and robust supervision

entrypoint.sh

@@ -3,31 +3,85 @@ set -e
 
 # Configuration from environment
 SERVICE_NAME="navidrome"
+# Use Nomad allocation ID for a unique service ID
+SERVICE_ID="${SERVICE_NAME}-${NOMAD_ALLOC_ID:-$(hostname)}"
 PORT=4533
 CONSUL_HTTP_ADDR="${CONSUL_URL:-http://localhost:8500}"
 NODE_IP="${ADVERTISE_IP}"
+DB_LOCK_FILE="/data/.primary"
+NAVIDROME_PID=0
 
 # Tags for the Primary service (Traefik enabled)
 PRIMARY_TAGS='["navidrome","web","traefik.enable=true","urlprefix-/navidrome","tools","traefik.http.routers.navidromelan.rule=Host(`navidrome.service.dc1.consul`)","traefik.http.routers.navidromewan.rule=Host(`m.fbleagh.duckdns.org`)","traefik.http.routers.navidromewan.middlewares=dex@consulcatalog","traefik.http.routers.navidromewan.tls=true"]'
 
-NAVIDROME_PID=""
-SERVICE_ID="navidrome-${NODE_IP}-${SERVICE_NAME}"
+# --- Helper Functions ---
 
-cleanup() {
-    echo "Caught signal, shutting down..."
-    if [ -n "$NAVIDROME_PID" ]; then
-        echo "Stopping Navidrome (PID: $NAVIDROME_PID)..."
-        kill -TERM "$NAVIDROME_PID"
-        wait "$NAVIDROME_PID" || true
-    fi
-    echo "Deregistering service ${SERVICE_ID} from Consul..."
-    curl -s -X PUT "${CONSUL_HTTP_ADDR}/v1/agent/service/deregister/${SERVICE_ID}" || true
-    exit 0
+# Register Service with TTL Check
+register_service() {
+  echo "Promoted! Registering service ${SERVICE_ID}..."
+  # Convert bash list string to JSON array if needed, but PRIMARY_TAGS is already JSON-like
+  curl -s -X PUT "${CONSUL_HTTP_ADDR}/v1/agent/service/register" -d "{
+    \"ID\": \"${SERVICE_ID}\",
+    \"Name\": \"${SERVICE_NAME}\",
+    \"Tags\": ${PRIMARY_TAGS},
+    \"Address\": \"${NODE_IP}\",
+    \"Port\": ${PORT},
+    \"Check\": {
+      \"DeregisterCriticalServiceAfter\": \"1m\",
+      \"TTL\": \"15s\"
+    }
+  }"
 }
 
-trap cleanup SIGTERM SIGINT
+# Send Heartbeat to Consul
+pass_ttl() {
+  curl -s -X PUT "${CONSUL_HTTP_ADDR}/v1/agent/check/pass/service:${SERVICE_ID}" > /dev/null
+}
 
-echo "Starting leadership-aware entrypoint..."
+# Deregister Service
+deregister_service() {
+  echo "Demoted/Stopping. Deregistering service ${SERVICE_ID}..."
+  curl -s -X PUT "${CONSUL_HTTP_ADDR}/v1/agent/service/deregister/${SERVICE_ID}"
+}
+
+# Start Navidrome in Background
+start_app() {
+  echo "Node is Primary. Starting Navidrome..."
+  
+  # Ensure DB path and local data folder are set
+  export ND_DATABASE_PATH="/data/navidrome.db"
+  export ND_DATAFOLDER="/local/data"
+  mkdir -p /local/data
+
+  /app/navidrome &
+  NAVIDROME_PID=$!
+  echo "Navidrome started with PID ${NAVIDROME_PID}"
+}
+
+# Stop Navidrome
+stop_app() {
+  if [ "${NAVIDROME_PID}" -gt 0 ]; then
+    echo "Stopping Navidrome (PID ${NAVIDROME_PID})..."
+    kill -SIGTERM "${NAVIDROME_PID}"
+    wait "${NAVIDROME_PID}" 2>/dev/null || true
+    NAVIDROME_PID=0
+  fi
+}
+
+# --- Signal Handling (The Safety Net) ---
+# If Nomad stops the container, we stop the app and deregister.
+cleanup() {
+  echo "Caught signal, shutting down..."
+  stop_app
+  deregister_service
+  exit 0
+}
+
+trap cleanup TERM INT
+
+# --- Main Loop ---
+
+echo "Starting Supervisor. Waiting for leadership settle..."
 echo "Node IP: $NODE_IP"
 echo "Consul: $CONSUL_HTTP_ADDR"
 
@@ -35,51 +89,36 @@ echo "Consul: $CONSUL_HTTP_ADDR"
 sleep 5
 
 while true; do
-    # In LiteFS 0.5, .primary file exists ONLY on replicas.
-    if [ ! -f /data/.primary ]; then
-        # PRIMARY STATE
-        if [ -z "$NAVIDROME_PID" ] || ! kill -0 "$NAVIDROME_PID" 2>/dev/null; then
-            echo "Node is Primary. Initializing Navidrome..."
-            
-            # Register in Consul
-            echo "Registering as primary in Consul..."
-            curl -s -X PUT -d "{
-                \"ID\": \"${SERVICE_ID}\",
-                \"Name\": \"${SERVICE_NAME}\",
-                \"Tags\": ${PRIMARY_TAGS},
-                \"Address\": \"${NODE_IP}\",
-                \"Port\": ${PORT},
-                \"Check\": {
-                    \"HTTP\": \"http://${NODE_IP}:${PORT}/app\",
-                    \"Interval\": \"10s\",
-                    \"Timeout\": \"2s\"
-                }
-            }" "${CONSUL_HTTP_ADDR}/v1/agent/service/register"
-            
-            echo "Starting Navidrome with ND_DATABASE_PATH=/data/navidrome.db"
-            export ND_DATABASE_PATH="/data/navidrome.db"
-            export ND_DATAFOLDER="/local/data"
+  # In LiteFS 0.5, .primary file exists ONLY on replicas.
+  if [ ! -f "$DB_LOCK_FILE" ]; then
+    # === WE ARE PRIMARY ===
+    
+    # 1. If App is not running, start it and register
+    if [ "${NAVIDROME_PID}" -eq 0 ] || ! kill -0 "${NAVIDROME_PID}" 2>/dev/null; then
+      if [ "${NAVIDROME_PID}" -gt 0 ]; then
+        echo "CRITICAL: Navidrome crashed! Restarting..."
+      fi
+      start_app
+      register_service
+    fi
 
-            # Start Navidrome
-            /app/navidrome &
-            NAVIDROME_PID=$!
-            echo "Navidrome started with PID $NAVIDROME_PID"
-        fi
-    else
-        # REPLICA STATE
-        if [ -n "$NAVIDROME_PID" ] && kill -0 "$NAVIDROME_PID" 2>/dev/null; then
-            echo "Node transitioned to Replica. Stopping Navidrome..."
-            kill -TERM "$NAVIDROME_PID"
-            wait "$NAVIDROME_PID" || true
-            NAVIDROME_PID=""
-            
-            echo "Deregistering primary service from Consul..."
-            curl -s -X PUT "${CONSUL_HTTP_ADDR}/v1/agent/service/deregister/${SERVICE_ID}" || true
-        fi
-        
-        # We don't register anything for replicas in this version to keep it simple.
-        # But we stay alive so LiteFS keeps running.
+    # 2. Maintain the heartbeat (TTL)
+    pass_ttl
+    
+  else
+    # === WE ARE REPLICA ===
+    
+    # If App is running (we were just demoted), stop it
+    if [ "${NAVIDROME_PID}" -gt 0 ]; then
+      echo "Lost leadership. Demoting..."
+      stop_app
+      deregister_service
     fi
     
-    sleep 5
-done
+    # No service registration exists for replicas to keep Consul clean.
+  fi
+
+  # Sleep short enough to update TTL (every 5s is safe for 15s TTL)
+  sleep 5 &
+  wait $! # Wait allows the 'trap' to interrupt the sleep instantly
+done