Lead Balloon

Wraps http.Server with graceful shutdown logic. Useful for ensuring service within fail-fast applications.

With its default configuration, a LeadBalloon server will close out by:

1. Emitting a 'closing' event
2. Servicing all existing requests (subject to a timeout)
3. Sending a 502 (Bad Gateway) response to any new requests

When the process finishes closing, this server will emit the usual 'close' event with no arguments (served closed gracefully) or an error (some connections timed out).

Note: in good, fail-fast fashion, unhandled exceptions in the server logic remain exceptional. No assumptions are made here about whether or not they can be recovered, and no attempt is made to recover them.

Usage

var createServer = require('leadballoon').createServer;

function handleRequest (req, res) {
  res.statusCode = 200;
  res.end('Hello, world');
}

var server = createServer(handleRequest, {
  timeout: 5000,
});

server.listen(process.env.PORT);

Later, to close the server while resolving as many open connections as possible:

server.close();

Options:

• timeout Number - the time (ms) to wait for connections to close before forcing a hard shutdown. Default: 10000.

• closingHandler Function - a (req, res) handler for requests received while the server is shutting down. Default: leadballoon.sendUnavailable.

Events:

• 'closing' - emitted when the server begins shutting down

Cleaning up

With the server closed, it's polite to bring the process down. This is the time to print any last words and exit with an appropriate status.

server.on('close', function (err) {
  if (err) {
    console.error('Went down hard', err);
    process.exit(1);
  }

  process.exit(0);
});

License

MIT