This is a quick node.js daemonizer I put together for debugging websockets, it can be called from the command line (without arguments) to run without daemonization, and also accepts start/stop/restart/stat with verbose outputs plus –daemonize/–kill/–proc for scripted calls. The actual usage is 1 call which takes a callback but the use case included below is clustered so it’s a bit longer. No non-node.js dependencies (external modules) required.
I make no guarantee that this will work or even that you won’t destroy your system with it, use at your own risk, I’m not liable.
PHP
The –daemonize option is a bit special, as it was designed explicitly for easy use from PHP (so the daemon can be called on demand to do things like create a web socket listener then shut itself down when no longer needed.)
<?php
echo shell_exec('/usr/local/bin/node /full/path/to/main.js --daemonize');
?>
./main.js
require('./inc/daemonizer.js').daemonize(() => {
const cluster = require('cluster');
const numCPUs = require('os').cpus().length;
if (cluster.isMaster) {
//daemon starting
process.on('SIGTERM', () => {
for (const id in cluster.workers) {
cluster.workers[id].send('shutdown');
}
process.exit(0);
});
for (var i = 0; i < numCPUs; i++) { cluster.fork({ 'ID': i }); } cluster.on('exit', (worker, code, signal) => {
//worker died
});
} else {
//worker starting
process.on('message', (msg) => {
if (msg === 'shutdown') { process.exit(0); }
});
for (var i = 0; i < 10000000000; i++) {
if ((i % 100000000) == 0) { console.log(i); }
}
}
});
./inc/daemonizer.js
function getDaemonPID(stdout, callback) {
let c, o = false;
stdout = stdout.split('\n');
let pid = 0;
for (let l = 0; l < stdout.length; l++) {
c = 0; o = !(stdout[l][0] == ' ');
for (let i = 0; i < stdout[l].length; i++) { if (o && (stdout[l][i] != ' ')) { o = !o; c++; if (c == 2) { pid = stdout[l].substr(i).split(' ')[0]; } else if ((c == 3) && (stdout[l].substr(i).split(' ')[0].toString() == '1')) { callback(pid); return; } } else if ((!o) && (stdout[l][i] == ' ')) { o = !o; } } } callback(0); } function __start(mode) { if (mode == 'restart') { console.log('Restarting...'); } var spawn = require('child_process').spawn; var d = spawn(process.execPath, [process.argv[1], '--daemon'], { detached: true, stdio: ['ignore', 'ignore', 'ignore', 'ipc'] }); d.unref(); d.disconnect(); console.log((mode == 'daemonize' ? '' : 'Started with pid: ') + d.pid.toString()); } function start(mode) { const exec = require('child_process').exec; exec('ps -xwwl | grep "' + process.argv[1] + ' --daemon" | grep -Ev "ps -xwwl " | grep -Ev "grep" | grep -Ev "daemonize"', (err, stdout, stderr) => {
getDaemonPID(stdout, (pid) => {
if (pid == 0) { // spawn the daemon
if (mode == 'start') { console.log('Not started, starting...'); }
__start(mode);
} else {
console.log((mode == 'daemonize' ? '' : 'Already started with pid: ') + pid.toString());
}
});
});
}
function stop(mode, restart) {
const exec = require('child_process').exec;
exec('ps -xwwl | grep "' + process.argv[1] + ' --daemon" | grep -Ev "ps -xwwl " | grep -Ev "grep" | grep -Ev "daemonize"', (err, stdout, stderr) => {
let c, o = false;
stdout = stdout.split('\n');
let pid = 0;
let promises = [];
for (let l = 0; l < stdout.length; l++) {
c = 0; o = !(stdout[l][0] == ' ');
for (let i = 0; i < stdout[l].length; i++) { if (o && (stdout[l][i] != ' ')) { o = !o; c++; if (c == 2) { (function (pid) { if (parseInt(pid) > 1) {
promises.push(new Promise((resolve, reject) => {
exec('kill ' + pid, (err, stdout, stderr) => {
console.log((mode != 'kill' ? 'Stopped pid: ' : '') + pid.toString());
resolve(pid);
});
}));
}
})(stdout[l].substr(i).split(' ')[0]);
break;
}
} else if ((!o) && (stdout[l][i] == ' ')) { o = !o; }
}
}
if (promises.length < 1) { console.log((mode != 'kill' ? 'Already stopped' + (restart ? ', starting' : '') + '.' : '0')); if (restart) { __start('start'); } } else if (restart) { Promise.all(promises).then((values) => { __start('restart'); }); }
});
}
exports.daemonize = function (daemonCode) {
let startMode = '';
let stopMode = '';
if (process.argv.indexOf('--help') >= 0) {
console.log('Usage: ' + process.execPath + ' ' + process.argv[1] + '[ option]');
console.log('Available options:');
console.log('\tstart Starts the daemon with verbose output.');
console.log('\t--daemonize Starts the daemon and outputs the pid, or just outputs the pid if it is already running.');
console.log('\tstop Stops the daemon with verbose output.');
console.log('\tstat Determine the state of the daemon.');
console.log('\t--kill Stops the daemon and outputs pids when complete.');
console.log('\t--proc Return the pid of the daemon if it is running or zero if it is not running.');
console.log('\trestart Restarts the daemon with verbose output.');
console.log('\t--help Outputs this set of help messages.');
return;
} else if (process.argv.indexOf('start') >= 0) {
startMode = 'start';
} else if (process.argv.indexOf('--daemonize') >= 0) {
startMode = 'daemonize';
} else if (process.argv.indexOf('stop') >= 0) {
stopMode = 'stop';
} else if (process.argv.indexOf('--kill') >= 0) {
stopMode = 'kill';
} else if (process.argv.indexOf('restart') >= 0) {
stopMode = 'stop';
startMode = 'restart';
} else if (process.argv.indexOf('stat') >= 0) {
console.log('Checking status...');
const exec = require('child_process').exec;
exec('ps -xwwl | grep "' + process.argv[1] + ' --daemon" | grep -Ev "ps -xwwl " | grep -Ev "grep" | grep -Ev "daemonize"', (err, stdout, stderr) => {
getDaemonPID(stdout, (pid) => {
if (pid == 0) { // spawn the daemon
console.log('Not started.');
} else {
console.log('Started with pid: ' + pid.toString());
}
});
});
return;
} else if (process.argv.indexOf('--proc') >= 0) {
const exec = require('child_process').exec;
exec('ps -xwwl | grep "' + process.argv[1] + ' --daemon" | grep -Ev "ps -xwwl " | grep -Ev "grep" | grep -Ev "daemonize"', (err, stdout, stderr) => {
getDaemonPID(stdout, (pid) => {
if (pid == 0) {
console.log('0');
} else {
console.log(pid.toString());
}
});
});
return;
}
if ((startMode.length > 0) && (stopMode.length > 0) && (startMode != 'daemonize') && (stopMode != 'kill')) { console.log('Checking status...'); }
if (stopMode.length > 0) {
stop(stopMode, startMode == 'restart');
return;
} else if (startMode.length > 0) {
start(startMode);
return;
}
daemonCode();
};