amqp-delegate

amqp-delegate

A very simplistic, but performant, remote worker system that uses AMQP to coordinate jobs.

branch	status	coverage	notes
develop			Work in progress
master			Latest stable release

Worker

const { makeWorker } = require('amqp-delegate')

const worker = makeWorker({
  url: <the url of the amqp server> - defaults to ampq://localhost,
  name: <the name of the worker> — required,
  task: <any pure async function> — required
  onError: err => { // optional
    console.error('A connection error happened', err) // or do something clever
  }
  onClose: () => { // optional
    console.log('The connection has closed.') // or do something clever
  }
})

// start it
worker.start().then(() => {
  console.log('worker', worker.name, 'started')
})

// stop it
worker.stop().then(() => {
  console.log('worker', worker.name, 'stopped')
})

Delegator

const { makeDelegator } = require('amqp-delegate')

const delegator = makeWorker({
  exchange: <the name of the exchange to use> — defaults to '',
  url: <the url of the amqp server> - defaults to ampq://localhost,
  onError: err => { // optional
    console.error('A connection error happened', err) // or do something clever
  }
  onClose: () => { // optional
    console.log('The connection has closed.') // or do something clever
  }
})

delegator
  .start()
  .then(() => {
    delegator.invoke('worker name', ...params)
    console.log('job name', result)
  })
  .catch(err => {
    console.error('worker name', err)
  })

A concrete example

The worker

const task = (a, b) =>
  new Promise(resolve => setTimeout(() => resolve(a + b), 10))

const worker = makeWorker({
  name: 'adder',
  task
})

worker
  .start()
  .then(() => {
    process.on('SIGINT', () => {
      worker
        .stop()
        .then(() => {
          process.exit(0)
        })
    })
  })
  .catch(err => {
    console.error('caught', err)
  })

The delegator

const delegator = makeDelegator()

delegator
  .start()
  .then(() => delegator.invoke('adder', 10, 15))
  .then(result => {
    console.log('result', result)
  })
  .catch(err => {
    console.error('caught', err)
  })

TODO

• documentation
• publish to npm

Development

Prerequisites

• NodeJS, version 10.15.0 or better (I use nvm to manage Node versions — brew install nvm.)
• Docker (Use Docker for Mac, not the homebrew version)

Initialisation

npm install

To Start the queue server for integration testing.

docker-compose up -d

Runs Rabbit MQ.

Test it

• npm test — runs the unit tests (does not need rabbitmq)
• npm run test:unit:cov — runs the unit tests with code coverage (does not need rabbitmq)
• npm run test:integration — runs the integration tests (needs rabbitmq)

note Node 11.7+ breaks nyc and mocha — see https://github.com/nodejs/node/issues/25650

Lint it

npm run lint

Contributing

Please see the contributing notes.