graceful-shutdown

Graceful Shutdown

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• Best Practices

Overview

Implement proper shutdown procedures to ensure all requests are completed, connections are closed, and resources are released before process termination.

When to Use

• Kubernetes/Docker deployments
• Rolling updates and deployments
• Server restarts
• Load balancer drain periods
• Zero-downtime deployments
• Process managers (PM2, systemd)
• Long-running background jobs
• Database connection cleanup

Quick Start

Minimal working example:

import express from "express";
import http from "http";

class GracefulShutdownServer {
  private app: express.Application;
  private server: http.Server;
  private isShuttingDown = false;
  private activeConnections = new Set<any>();
  private shutdownTimeout = 30000; // 30 seconds

  constructor() {
    this.app = express();
    this.server = http.createServer(this.app);
    this.setupMiddleware();
    this.setupRoutes();
    this.setupShutdownHandlers();
  }

  private setupMiddleware(): void {
    // Track active connections
    this.app.use((req, res, next) => {
      if (this.isShuttingDown) {
        res.set("Connection", "close");
        return res.status(503).json({
          error: "Server is shutting down",
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide	Contents
Express.js Graceful Shutdown	Express.js Graceful Shutdown
Kubernetes-Aware Shutdown	Kubernetes-Aware Shutdown
Worker Process Shutdown	Worker Process Shutdown
Database Connection Pool Shutdown	Database Connection Pool Shutdown
PM2 Graceful Shutdown	PM2 Graceful Shutdown
Python/Flask Graceful Shutdown	Python/Flask Graceful Shutdown

Best Practices

✅ DO

• Handle SIGTERM and SIGINT signals
• Stop accepting new requests immediately
• Wait for in-flight requests to complete
• Set reasonable shutdown timeouts
• Close database connections properly
• Flush logs and metrics
• Fail health checks during shutdown
• Test shutdown procedures
• Log shutdown progress
• Use graceful shutdown in containers

❌ DON'T

• Ignore shutdown signals
• Force kill processes without cleanup
• Set unreasonably long timeouts
• Skip resource cleanup
• Forget to close connections
• Block shutdown indefinitely