Master process class managing workers

master-worker.ts

import * as cluster from 'cluster'

class Master {
  private shutdownInProgress: boolean = false
  private hasCleanWorkerExit: boolean = true
  
  private processStr = `${cluster.isMaster ? "master" : "worker"} process ${process.pid}`
  
  gracefulClusterShutdown = (signal: NodeJS.Signals) => async () => {
    //defined in worker-shutdown.ts (https://gist.github.com/Dante-101/de2fbd5071bec0c0647f5c9fa1cfa179)
  }
  
  shutdownWorkers = (signal: NodeJS.Signals) => {
    //defined in worker-shutdown.ts (https://gist.github.com/Dante-101/de2fbd5071bec0c0647f5c9fa1cfa179)
  }
  
  async stop() {
    //stop listening
    //disconnect with db
    //any other cleanup
  }
    
  async start() {
    if (cluster.isMaster) {
      await this.bootWorkers(4)
    }
    process.on('SIGTERM', this.gracefulClusterShutdown('SIGTERM'))
    process.on('SIGINT', this.gracefulClusterShutdown('SIGINT'))
  }
  
  bootWorkers = async (numWorkers: number) => {
    log.info(`Setting ${numWorkers} workers...`);

    for (let i = 0; i < numWorkers; i++) {
      cluster.fork()  //create the workers
    }

    //Setting up lifecycle event listeners for worker processes
    cluster.on('online', worker => {
      log.info(`worker process ${worker.process.pid} is online`)
    })

    cluster.on('exit', (worker, code, signal) => {
      log.info(`worker ${worker.process.pid} exited with code ${code} and signal ${signal}`)
      if (this.shutdownInProgress && code != 0) {
        this.hasCleanWorkerExit = false
      }
    })

    cluster.on('disconnect', worker => {
      log.info(`worker process ${worker.process.pid} has disconnected`)
    })
  }
}