startup

Node.js HTTP app runner

This Fork

Node 4 can use too much memory on a system such as Heroku unless specific flags are set. This forked version allows unknown arguments to be passed into startup.

Here is an example of a Procfile entry for a Heroku 2x dyno:

web: ./node_modules/.bin/startup start -w 1 --max_old_space_size=960

Features

• Port Binding
• Hot-Reloading
• Domains
• Cluster
• SIGTERM and SIGINT handling

Usage

All startup requires is an exported http app:

Express Example

var express = require("express");

// Export the express app
var app = module.exports = express();

app.get("/", function (req, res){
  res.send("Hello!");
});

Connect Example

var connect = require("connect");

// Export the connect app
var app = module.exports = connect();

app.use(function (req, res, next){
  res.send("Hello!");
});

Vanilla HTTP Example

var http = require("http");

// Create the http server
var server = http.createServer(function (req, res){
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.end("Hello!");
});

// Export it
module.exports = server;

To start the app, just run:

startup start

and startup will bind to the PORT environment variable.

Sockjs Example

To install any handlers needed, sockjs for example, listen for the ready event:

var express = require("express")
  , sockjs = require("sockjs");

// Export the express app
var app = module.exports = express();

// Setup the sockjs server
var echo = sockjs.createServer();
echo.on('connection', function(conn) {
  conn.on('data', function(message) {
    conn.write(message);
  });
  conn.on('close', function() {});
});

app.get("/", function (req, res){
  res.send("Hello!");
});

// Install the handlers
app.on("ready", function(server){
  echo.installHandlers(server, {prefix: "/echo"});
});

Listening Callback

To know when the server is listening on a port, bind to the listening event:

var express = require("express");

// Export the express app
var app = module.exports = express();

app.get("/", function (req, res){
  res.send("Hello!");
});

app.on("listening", function(server){
  console.log("My app is listening");
});

Commands

###startup start

Starts app listening on the PORT environment variable.

###startup middleware

Lists loaded middleware (express and connect only) without running the app.

###startup routes

Lists loaded middleware (express only) without running the app.

###startup settings

Lists app settings (express only) without running the app.

Port Binding

startup will look for the PORT environment variable and try to bind to it. If not value is found, it defaults to 3000. You can also set it by executing startup start -P <port>.

Hot-Reload

To enable hot-reload, set the NODE_ENV environment variable to development. You may also specify --dev to force it.

Read more about node-dev, the tool startup uses.

Domains

Domains were introducted in v0.8 and act as a way to isolate uncaught exceptions in a process. This proves useful for http servers when we want each request to be handled in a unique domain, as to not crash the whole server.

Setting it up requires a bit of boilerplate code that comes built in to startup.

You can also provide a custom error handler for when you do get an uncaught exception by exporting errorHandler in your app:

var express = require("express");

// Export the express app
var app = module.exports = express();

app.get("/", function (req, res){
  res.send("Hello!")
});

module.exports.errorHandler = function (err, req, res) {
  res.send("There was an error!");
};

Cluster

Cluster allows a server to take advantage of all of the cores on a system instead of being limited by node's single thread. Cluster mode is enabled by default in production.

SIGTERM and SIGINT

startup reacts to system messages to enable clean exits. When it receives a SIGTERM it stops accepting connections and gives all of the current connections 3 seconds (overridable by setting SOCKET_TIMEOUT) to clean up and shut down. In environments like heroku it is very important the server reacts to these messages since the platform can shut it down at any time.