look up the IPs of the containers for a Docker service

lookup-service-ips.js

const dns = require('dns')

function lookup (serviceName) {
  const tasks = `tasks.${serviceName}`
  return new Promise((resolve, reject) => {
    dns.lookup(tasks, { all: true }, (err, addresses, family) => {
      if (err) {
        return reject(err)
      }
      const filtered = addresses.filter(address => address.family === 4)
      const ips = filtered.map(x => x.address)
      resolve(ips)
    })
  })
}

async function main () {
  const result = await lookup('hello')
  console.log(result)
}

main()