start-stop-daemon

An 1-function Node.js module to easily create native child_process.fork start-stop-daemon scripts.
Created daemons are self-monitored and restart automatically when crashing (a custom crash handler can be attached too).

Installation

npm install start-stop-daemon

Usage

//file daemon.js    
startStopDaemon([options], function() {
  //awesome code you want to daemonize
});

• Start the daemon with the command node daemon.js start
• Stop the daemon with the command node daemon.js stop
• Restart the daemon with the command node daemon.js restart
• Get the status of the daemon with the command node daemon.js status
• Run the script not as a daemon with the command node daemon.js run

Possible options fields

• pidFile: the file to log the daemon PID. Default to 'daemon.pid'.
• outFile: the file to log the daemon stdout. Default to 'daemon.out'.
• errFile: the file to log the daemon crashes (uncaught exceptions). Default to 'daemon.err'.
• maxCrash: the maximum number of crashes by minute. Past this number, the daemon exits. Default to 5.
• onStart: listener fired when we start the daemon. Default to displaying a start message.
• onStop: listener fired when we stop the daemon. Default to displaying a stop message.
• onStatus: listener fired when we get the status of the daemon. Default to displaying a status message.
• onCrash: listener fired when the daemon crashes. Default to restarting the daemon.

The options default fields can be found in the startStopDaemon.defaultOptions object.

Command-line options

--logAppend           append to existing stdout and stderr files
--pid <pidFile>       specify pid file
--out <stdoutFile>    specify stdout file
--err <stderrFile>    specify stderr file
--max-crash <value>   specify maximum number of crashes by minute

You can also pass your own arguments that will be transferred to the daemon, a port argument for example:

node daemon.js start --port 1095 --out daemon.log  --err daemon.log  --logAppend

we make sure that argv remains unpolluted in your script: process.argv[2] === '--port' and process.argv[3] === '1095' in the daemon process (like if start-stop-daemon was not being used).

Handling crashes (in the onCrash listener only)

Exit daemon:

startStopDaemon.cleanCrash('exit')

Restart the daemon, append stdout to the previous stdout file, append the crash error to the error file:

startStopDaemon.cleanCrash('restart')

Example 1: server.js, a stupid web server daemon

    var startStopDaemon = require('start-stop-daemon');
    var http = require('http');

    startStopDaemon(function() {
      http.createServer(function(req, res) {
        console.log(req.connection.remoteAddress + ' at ' + new Date());
        res.end(new Date() + ': Hello world');
      }).listen(8080);
    });

Execute the command node server.js start
Play with the server in your browser on http://localhost:8080
Execute the command node server.js status
Execute the command node server.js stop
Check the stdout file server.out.

Example 2: crasher.js, a timer daemon that crashes every second

    var startStopDaemon = require('start-stop-daemon');

    var options = {
      outFile: 'customStdoutFile.log', 
      errFile: 'customErrorFile.log'
    };

    options.onCrash = function(e) {

      // Your own code to handle the crash: a mail notification for example
      //....

      // Log the crash in the stdout file
      console.log('CRASH');

      // Restart the daemon if it crashes during the 3 first seconds, exit the daemon otherwise
      new Date() - this.startDate <= 3000 ?
        startStopDaemon.cleanCrash('restart') :
        startStopDaemon.cleanCrash('exit');

     }

    startStopDaemon(options, function() {
      var count = 0;
      setInterval(function() {
        if (count >= 5)
          throw new Error('to crash the timer');    
        console.log('0.' + 2 * count++ + ' second');             
      }, 200);      
    });

Execute the command node crasher.js start
Wait 4 seconds then execute the command node crasher.js status to check that the daemon correctly exited
Check the stdout file customStdoutFile.log and the error file customErrorFile.log.

MIT License

Copyright (c) 2012 Jie Meng-Gerard contact@jie.fr

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.