node-app-hive

Cluster based NodeJS process manager. TCP ports or IPC sockets can be used.

---

Usage:

1. Create a folder for an application sockets, for example /home/my-app/run.

2. Create an executable application script, for example (/home/my-app/app.js):

   #!/bin/sh
   ':' //; exec /usr/bin/env node "$0" "$@"
   
   const path = require('path');
   const hive = require('node-app-hive');
   
   // Using TCP ports:
   hive.bind('example-node-app', {
       command_conn: {
           port: 4000,
           host: 'localhost',
           // -OR- Using IPC:
           //path: path.normalize(`${__dirname}/run`) + '/%namehive.command.sock'
       },
       worker_conn: {
           port: '4001 + %numworker',
           host: 'localhost',
           // -OR- Using IPC:
           //path: path.normalize(`${__dirname}/run`) + '%namehive.worker%numworker.sock'
       },
       worker_script: require.resolve('./worker'),
       numworkers: 1,
       watch_glob: [`/home/my-app/src/**/*.{js,json}`]
   }).runtime();
   
   

3. Make the script executable:

   $ chmod +x /home/my-app/app.js

4. To start an application run a command:

   $ /home/my-app/app.js

   If you want to watch for the code changes, then you can run the script with a watch argument:

   $ /home/my-app/app.js watch

   You can learn more about watcher glob format here

---

Commands:

You can emit a command for the running application. To do so execute:

$ /home/my-app/app.js <command>

• status -- get the application status.
• restart -- restart all workers.
• reload -- graceful (zero downtime) workers reloading.

---

Persist Master

While master is running, it watches for the workers being alive. If some worker would be terminated, then master will re-spawn that worker immediately. You should persist the master script by yourself.

For example, using systemd:

[Unit]
Description=Sample Clustered Node Application

[Service]
WorkingDirectory=/home/my-app
ExecStart=/usr/bin/sh /home/my-app/app.js
Restart=always
StandardOutput=syslog
StandardError=syslog
SyslogIdentifier=node-sample-app
User=www-data
Group=www-data

[Install]
WantedBy=multi-user.target

---

Exit policy

When you emitting restart or reload command, by default used simple halt policy, which invoking process.exit() for each worker node.

Alternatively you can use exit_policy: 'SIGTERM'. In this case, you should manually handle SIGTERM signal in your worker script. For example:

const http = require('http');

http.createServer((req, res) => {
    res.writeHead(200, {'Content-Type': 'text/plain'});
    res.write('Hello World!');
    res.end();
}).listen(8080);

process.on('SIGTERM', () => {
    console.info('SIGTERM signal received.');
    console.log('Closing http server.');
    server.close(() => {
        console.log('Http server closed.');
        process.exit();
    });
});