feat: Add PM2 ecosystem configuration for production process management

ecosystem.config.js

@@ -0,0 +1,76 @@
+/**
+ * PM2 Ecosystem Configuration
+ * ----------------------------
+ * Process management for the DeenBridge backend in production.
+ *
+ * Start:
+ *   pm2 start ecosystem.config.js --env production
+ *
+ * Reload all cluster instances with zero downtime:
+ *   pm2 reload ecosystem.config.js --update-env
+ *
+ * Cluster mode spreads the app across all CPU cores (instances: "max"),
+ * with auto-restart on crash and restart when memory exceeds a threshold.
+ *
+ * Log ROTATION is handled by the pm2-logrotate module. It is NOT bundled
+ * with pm2 itself, so after first install run:
+ *   pm2 install pm2-logrotate
+ *   pm2 set pm2-logrotate:max_size 50M          # rotate files > 50MB
+ *   pm2 set pm2-logrotate:retain 10             # keep 10 rotated files
+ *   pm2 set pm2-logrotate:compress true         # gzip rotated logs
+ *   pm2 set pm2-logrotate:rotateInterval '0 0 * * *'  # daily rotation
+ */
+
+export default {
+  apps: [
+    {
+      name: "dnb-backend",
+
+      // Entry point (ESM — the repo's package.json declares "type": "module").
+      script: "./server.js",
+      cwd: "./",
+
+      // ── Cluster mode for multi-core usage ────────────────────────────────
+      // instances "max" (or -1) spawns one worker per available CPU core.
+      exec_mode: "cluster",
+      instances: "max",
+
+      // ── Resiliency: auto-restart + max-memory-restart ───────────────────
+      // autorestart: restart on crash (or peaceful exit) by default.
+      autorestart: true,
+      // Watch disabled in production — deploys should trigger restarts.
+      watch: false,
+      // Kill process if it exceeds memory, then restart it.
+      max_memory_restart: "1G",
+      // Grace period before considering a process stable.
+      min_uptime: "10s",
+      // Wait before restarting a crashed app.
+      restart_delay: 4000,
+      // Give app up to 30s to listen before forcing a reload.
+      listen_timeout: 30000,
+      kill_timeout: 10000,
+      // Consecutive unstable restarts before PM2 gives up (default 16).
+      max_restarts: 16,
+
+      // ── Environment ──────────────────────────────────────────────────────
+      env: {
+        NODE_ENV: "production",
+        PORT: 5000,
+      },
+      env_production: {
+        NODE_ENV: "production",
+      },
+
+      // ── Logging & rotation ───────────────────────────────────────────────
+      // Rotated/aggregated log locations (see pm2-logrotate module notes
+      // above for auto-rotation / compression / retention).
+      out_file: "./logs/out.log",
+      error_file: "./logs/error.log",
+      // Avoid per-PID log suffixes so all cluster workers share one log file.
+      merge_logs: true,
+      // Prefix every log line with a timestamp.
+      log_date_format: "YYYY-MM-DD HH:mm:ss Z",
+      time: true,
+    },
+  ],
+};