respawn's Introduction

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respawn

Spawn a process and restart it if it crashes.

npm install respawn

Usage

It is easy to use

var respawn = require('respawn')

var monitor = respawn(['node', 'server.js'], {
  env: {ENV_VAR:'test'}, // set env vars
  cwd: '.',              // set cwd
  maxRestarts:10,        // how many restarts are allowed within 60s
                         // or -1 for infinite restarts
  sleep:1000,            // time to sleep between restarts,
  kill:30000,            // wait 30s before force killing after stopping
  stdio: [...]           // forward stdio options
})

monitor.start() // spawn and watch

Optionally you can specify the command to to spawn in the option map as command: [...]

API

monitor.start() Starts the monitor
monitor.stop(cb) Stops the monitor (kills the process if its running with SIGTERM)
monitor.status Get the current monitor status. Available values are running, stopping, stopped, crashed and sleeping

Events

monitor.on('start') The monitor has started
monitor.on('stop') The monitor has fully stopped and the process is killed
monitor.on('crash') The monitor has crashed (too many restarts or spawn error).
monitor.on('sleep') monitor is sleeping
monitor.on('spawn', process) New child process has been spawned
monitor.on('exit', code, signal) child process has exited
monitor.on('stdout', data) child process stdout has emitted data
monitor.on('stderr', data) child process stderr has emitted data
monitor.on('warn', err) child process has emitted an error

Graceful restart

To do graceful restart simply have your app stop gracefully when receiving SIGTERM and do

// graceful restart (do not wait for old process to die)
monitor.stop()
monitor.start()

// hard restart (wait for old process to die)
monitor.stop(function() {
  monitor.start()
})