w8r

Poll to see if a service is running, and once it is, fork a new node process

Huh?

(net|http).createServer()#listen is async. Sometimes you want to do something but only after the a server has started. You can just hope it starts in time, or you can use this.

Also useful for docker-compose -- if you have dependent containers, docker will wait for the container to be ready, but it doesn't know if the service is ready yet. This makes sure your app won't start until the service it depends on is available.

Usage

npm install --save w8r

const w8r = require('w8r')
const serverlist = [{host: 'redis', port: 6379}, '/var/run/mysql']
w8r(50, serverlist, 'start-server.js', (err, child) => {
  // both services are up and running!
  // and child is your child process you started!
})

API

• w8r(checkInterval:number, serverList:array, procfile:string, procargs?:array(string), procopts?:object, cb:function) Spawn a net client to check to see if the server at the provided host:port is available every checkInterval ms and then fork a new node process.

• checkInterval:number - amount of delay, in ms, before trying again

• profile:string - the path to the entry point for the child process

• procargs:array(string) (optional) - arguments to your command

• procopts:object (optional) - options for the child_process.fork command

The serverList array can contain two separate object types:

• paths to unix domain sockets (e.g.: /var/run/mysql)
• objects containing a port and host key (e.g.: {port: 6379, host: 'redis'})

Licence

Copyright © 2016 Scripto, LLC. Apache-2.0 Licensed.