💻 🌍 pm2-master-process

When using PM2 (Process Manager) for managing your Node.js applications, you will probably later need to run specific tasks only on a single instance (process). This small library solves this problem and gives you simple API and method decorators that you can use. Does this library help you? Do not forget to give it a ⭐️!

⭐️ Features

• Allow running specific tasks only on a single instance
• Supports PM2 restarts and scaling
• Decorators for easy use
• Retrieves number of slaves

🚀 Installation

First you need to install this package and related pm2 package.

yarn add pm2-master-process pm2

npm install pm2-master-process pm2

Without any configuration, the environment variable which tells us the instance of the id is NODE_APP_INSTANCE (source). If you have a problem accessing this environment variable, edit your pm2 ecosystem file and change the value of field instance_var to YOUR_CUSTOM_ENV_NAME.

🤘🏻 Usage

Without custom configuration

import { isMasterInstance } from 'pm2-master-process'

if (await isMasterInstance()) {
  console.info(`I am master!`)
} else {
  console.info(`I am a slave.`)
}

With custom configuration

import { isMasterInstance, Pm2MasterProcessConfig } from 'pm2-master-process'

const config: Partial<Pm2MasterProcessConfig> = {
  instanceIdPath: `YOUR_CUSTOM_ENV_NAME`, // process.env.YOUR_CUSTOM_ENV_NAME
  logger: false,
}

if (await isMasterInstance(config)) {
  console.info(`I am master!`)
} else {
  console.info(`I am a slave.`)
}

Using decorators

import { MasterInstance, NotMasterInstance } from 'pm2-master-process';

class MyController {

  @Cron('0 0 0 * * *', {
    name: 'Validate FS',
  })
  @MasterInstance()
  runJob() {
    ...
  }

  @Cron('0 0 0 * * *', {
    name: 'Something else',
  })
  @NotMasterInstance()
  runDifferntJob() {
    ...
  }

}

✨ Feature functions

Retrieve number of slaves

import { getSlavesCount  } from 'pm2-master-process';

const slavesCount = await getSlavesCount()

Retrieve processes and not just instances

import { getInstances } from 'pm2-master-process';

const instances = await getInstances()

TODO

• Add tests,
• Add a support for connection with queue-based libraries.