cluster-collector

Collect information from all nodes in a NodeJs cluster. Either from the master node, or any single worker in the cluster. E.g. Used by a REST service to collect cluster statistics aggregation.

Example - Cluster master

const cluster = require('cluster')
const clusterCollector = require('cluster-collector')

cluster.setupMaster({ exec: __dirname + '/demo-child.js' })
cluster.fork({ demo_id: 0 })
cluster.fork({ demo_id: 1 });

(async function() {

    //delay for demo. You may want to listen to the 'online' event in production case.
    await new Promise(resolve => setTimeout(resolve, 1000))

    let options = {
        //filter: worker => true,    //filter workers to collect from
        //timeout: 10000,
        data: 'hello'            //a custom object to pass on
    }
    let ret = await clusterCollector.collect('myTopic', options)
    console.log('Cluster result collected from master', ret)

})().catch(console.error)

Example - Cluster worker

const clusterCollector = require('cluster-collector')

let demo_id = process.env.demo_id

//Add a handler which generates data for 'myTopic'.
//The handler can be either sync or async
clusterCollector.on('myTopic', async data => data + ' ' + demo_id);

(async function() {    
    //demo delay
    await new Promise(resolve => setTimeout(resolve, 2000))

    let options = {
        //timeout: 10000,
        data: 'mortal'        //a custom object to pass on
    }

    let ret = await clusterCollector.collect('myTopic', options)
    console.log('Cluster result collected from a child:', demo_id, ret)

})().catch(e => console.error('error', e.toString()))
    .then(() => setTimeout(process.exit, 1000))

Output

Cluster result collected from master [ 'hello 0', 'hello 1' ]
Cluster result collected from a child: 1 [ 'mortal 0', 'mortal 1' ]
Cluster result collected from a child: 0 [ 'mortal 0', 'mortal 1' ]