Graceful shutdown of a nodejs server

gracefulShutdown.js

'use strict';

/*
 * Usage:
 *
 * const gracefulShutdown = require('./app/utils/gracefulShutdown');
 *
 * const server = app.listen(port, callback)
 *
 * gracefulShutdown.init(server, logger);
 */

const assert = require('assert');

function init(server, logger, timeout) {
  assert.ok(server, 'server must be set');
  assert.ok(logger, 'logger must be set');

  const forcedTimeout = timeout || 20 * 1000;  // default timeout 20 secs

  function gracefulShutdown() {
    logger.info('Received SIGINT or SIGTERM. Shutting down gracefully...');

    server.close(() => {
      logger.info('Closed out remaining connections.');
      process.exit();
    });

    // force stop after timeout
    setTimeout(() => {
      logger.error('Could not close connections in time, forcefully shutting down');
      process.exit();
    }, forcedTimeout);
  }

  // e.g. kill
  process.on('SIGTERM', gracefulShutdown);

  // e.g. Ctrl + C
  process.on('SIGINT', gracefulShutdown);
}

module.exports.init = init;