Add container readiness checks and exclude local state from images

Adapted from MikaelKW/nodecast-tv-plus readiness and container context work.

Co-authored-by: MikaelKW <87399352+MikaelKW@users.noreply.github.com>

server/db.js

@@ -523,4 +523,4 @@ const users = {
   }
 };
 
-module.exports = { loadDb, saveDb, sources, hiddenItems, favorites, settings, users, getDefaultSettings, getUserAgent, USER_AGENT_PRESETS };
+module.exports = { loadDb, saveDb, checkHealth: readDbForMutation, sources, hiddenItems, favorites, settings, users, getDefaultSettings, getUserAgent, USER_AGENT_PRESETS };

server/index.js

@@ -8,6 +8,7 @@ const syncService = require('./services/syncService');
 require('./db');
 
 const app = express();
+app.locals.ready = false;
 const PORT = process.env.PORT || 3000;
 
 // Trust proxy headers (X-Forwarded-Proto, X-Forwarded-For, etc.)
@@ -154,6 +155,7 @@ async function loadPlugins() {
 
 // Graceful shutdown handler for plugins with shutdown hooks
 process.on('SIGTERM', async () => {
+    app.locals.ready = false;
     console.log('SIGTERM received, shutting down plugins...');
     for (const { name, plugin } of loadedPlugins) {
         if (plugin && typeof plugin.shutdown === 'function') {
@@ -169,6 +171,7 @@ process.on('SIGTERM', async () => {
 });
 
 // API Routes
+app.get('/api/health', require('./services/health'));
 app.use('/api/auth', require('./routes/auth'));
 app.use('/api/sources', require('./routes/sources'));
 app.use('/api/proxy', require('./routes/proxy'));
@@ -205,6 +208,7 @@ app.listen(PORT, async () => {
     await loadPlugins().catch(err => {
         console.error('Plugin initialization failed:', err);
     });
+    app.locals.ready = true;
 
     // Trigger background sync with delay to allow server to settle
     setTimeout(async () => {

server/services/health.js

@@ -0,0 +1,18 @@
+const database = require('../db');
+const { getDb } = require('../db/sqlite');
+
+async function health(req, res) {
+    res.setHeader('Cache-Control', 'no-store');
+    if (!req.app.locals.ready) return res.status(503).json({ status: 'unavailable' });
+    try {
+        await database.checkHealth();
+        getDb().prepare('SELECT 1').get();
+        // Readiness may change while the asynchronous JSON check is running.
+        if (!req.app.locals.ready) return res.status(503).json({ status: 'unavailable' });
+        res.json({ status: 'ok' });
+    } catch {
+        res.status(503).json({ status: 'unavailable' });
+    }
+}
+
+module.exports = health;