README

runfork

runfork runs a Node.js script isolated as a process.

Status

Category	Status
Version
Dependencies
Dev dependencies
Build
License

Installation

$ npm install runfork

Quick start

To use runfork first you need to add a reference to your application:

const { runfork } = require('runfork');

If you use TypeScript, use the following code instead:

import { runfork } from 'runfork';

Then to run a Node.js script, run runfork and provide the path to the script using an options object. In case the script can not be started, an exception is thrown:

const stop = runfork({ path: './app.js' });

Passing arguments to the fork

You can also pass arguments to the fork:

const stop = runfork({
  path: './app.js',
  args: [ '--type', 'test' ],
});

Passing environment variables to the fork

From time to time you need to set environment variables for the script being called. To do so provide an env property in the options object that contains the environment variables as key-value pairs:

const stop = runfork({
  path: './app.js',
  env: {
    PORT: 3000
  }
});

Passing Node.js arguments to the fork

You can also pass arguments to the Node.js call of the fork:

const stop = runfork({
  path: './app.js',
  nodeArgs: [ '--inspect' ],
});

Sending messages from the fork to the parent

To send messages from the fork to the parent use the process.send function from within your fork. In the parent provide an onMessage function to receive the messages:

const stop = runfork({
  path: './app.js',
  onMessage (message) {
    // ...
  }
});

Stopping the fork

Sometimes, e.g. when executing a long-running task, it may be necessary to stop the fork. For this, call the stop function that is returned.

This function will send 10 SIGINT signals with 10ms breaks in between. If the process does not respond to this, it finally sends a SIGKILL signal to kill the process.

As the stop function returns a promise, you can wait for the process to terminate:

const stop = runfork({ path: './app.js' });

// ...

await stop();

Detecting when the fork exits

To get notified when the script exits, provide the onExit property in the options object. This function will get called with the exit code as well as the stdout and the stderr streams:

const stop = runfork({
  path: './app.js',
  onExit (exitCode, stdout, stderr) {
    // ...
  }
});

Passing through output

For debugging purposes, it may make sense from time to time to simply pass through the original output. For this, provide the silent property in the options object and set it to false:

const stop = runfork({
  path: './app.js',
  silent: false
});

Running quality assurance

To run quality assurance for this module use roboter:

$ npx roboter

Usage no npm install needed!