Node.js Graceful Shutdown with Active Connection Draining

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
const http = require('http');

function setupGracefulShutdown(server, dbPool, timeoutMs = 10000) {
  let isShuttingDown = false;

  const shutdown = (signal) => {
    if (isShuttingDown) return;
    isShuttingDown = true;
    console.log(`Received ${signal}. Initiating graceful drainage...`);

    const forceKill = setTimeout(() => {
      console.error('Graceful shutdown timeout exceeded. Forcing termination.');
      process.exit(1);
    }, timeoutMs);

    server.close(async () => {
      try {
        console.log('HTTP connections drained. Closing database connection pool...');
        if (dbPool && typeof dbPool.end === 'function') {
          await dbPool.end();
        }
        clearTimeout(forceKill);
        console.log('Cleanup complete. Process exiting gracefully.');
        process.exit(0);
      } catch (err) {
        console.error('Error during teardown:', err);
        process.exit(1);
      }
    });
  };

  process.on('SIGTERM', () => shutdown('SIGTERM'));
  process.on('SIGINT', () => shutdown('SIGINT'));
}