DAR-7: Implement a dar-server.js file

server/package.json

@@ -4,7 +4,7 @@
   "description": "Deighton AR Server",
   "main": "src/server.js",
   "scripts": {
-    "start": "babel-node src/index.js",
+    "start": "babel-node src/dar-server.js",
     "start:prod": "NODE_ENV=production npm start",
     "build": "babel src -d dist -s",
     "serve": "NODE_ENV=production node dist/server.js",

server/src/DARServer.js

@@ -0,0 +1,98 @@
+import childProcess from 'child_process'
+import path from 'path'
+import chalk from 'chalk'
+import timers from 'timers'
+import autoBind from 'auto-bind2'
+
+export class DARServer {
+  constructor(toolName, log) {
+    autoBind(this)
+    this.toolName = toolName
+    this.log = log
+    this.actors = [
+      { name: 'api' },
+      { name: 'email' },
+      { name: 'image' },
+    ]
+  }
+
+  restart(actor) {
+    const timeSinceStart = Date.now() - actor.startTime
+
+    if (timeSinceStart < actor.timeToInit) {
+      actor.backOff += 1
+    } else {
+      actor.backOff = 0
+    }
+
+    const backOffTime = (Math.pow(2, Math.min(actor.backOff, 7)) - 1) * 1000
+
+    if (backOffTime > 0) {
+      this.log.warn(`Actor '${actor.name}' died quickly, waiting ${Math.floor(backOffTime / 1000)} seconds to restart`)
+    } else {
+      this.log.warn(`Actor ${actor.name} died, restarting`)
+    }
+
+    timers.setTimeout(() => {
+      actor.starts += 1
+      actor.startTime = Date.now()
+      actor.proc = childProcess.fork(actor.modulePath)
+      actor.proc.on('exit', (code, signal) => {
+        // Don't restart if the exit was clean or Control+C
+        if (code === 0 || signal === 'SIGINT') {
+          this.log.info(`Actor ${actor.name} terminated normally`)
+          return
+        }
+
+        this.restart(actor)
+      })
+      this.log.info(`Restarted actor '${actor.name}', pid ${actor.proc.pid}`)
+    }, backOffTime)
+  }
+
+  async run() {
+    let promises = []
+
+    this.actors.forEach((actor) => {
+      promises.push(new Promise((resolve, reject) => {
+        actor.modulePath = path.join(__dirname, actor.name)
+        actor.startTime = Date.now()
+        actor.backOff = 0
+        actor.timeToInit = actor.timeToInit || 3000
+        actor.proc = childProcess.fork(actor.modulePath)
+        actor.proc.on('exit', (code, signal) => {
+          const timeSinceStart = Date.now() - actor.startTime
+
+          if (timeSinceStart < actor.timeToInit) {
+            this.log.error(`Actor '${actor.name}' exited during initialization`)
+
+            if (this.actors) {
+              this.actors.forEach((otherActor) => {
+                if (otherActor !== actor) {
+                  this.log.info(`Terminating actor ${actor.name}, pid ${otherActor.proc.pid}`)
+                  otherActor.proc.kill('SIGINT')
+                  otherActor.proc = null
+                }
+              })
+
+              actor.proc = null
+              this.actors = null
+            }
+
+            return reject(new Error('All actors must initialize on first start'))
+          }
+
+          this.restart(actor)
+        })
+        timers.setTimeout(() => {
+          if (actor.proc) {
+            resolve()
+          }
+        }, actor.timeToInit)
+        this.log.info(`Started actor '${actor.name}', pid ${actor.proc.pid}`)
+      })) // new Promise()
+    })
+
+    return Promise.all(promises)
+  }
+}

server/src/dar-server.js

@@ -0,0 +1,27 @@
+#!/usr/bin/env node
+import { DARServer } from './DARServer'
+import pino from 'pino'
+import * as pinoExpress from 'pino-pretty-express'
+import path from 'path'
+
+const serviceName = 'dar-server'
+const isProduction = (process.env.NODE_ENV == 'production')
+let log = null
+
+if (isProduction) {
+  log = pino( { name: serviceName },
+    fs.createWriteStream(path.join(config.get('logDir'), serviceName + '.log'))
+  )
+} else {
+  const pretty = pinoExpress.pretty({})
+  pretty.pipe(process.stdout)
+  log = pino({ name: serviceName }, pretty)
+}
+
+const tool = new DARServer(path.basename(process.argv[1], '.js'), log)
+
+tool.run(process.argv.slice(2)).then((exitCode) => {
+  process.exitCode = exitCode
+}).catch((err) => {
+  console.error(err)
+})

server/src/server.js

@@ -1,9 +0,0 @@
-import childProcess from 'child_process'
-
-const actors = [ 'api', 'email', 'image' ]
-
-// TODO: spawn index.js in each of these sub-directories
-
-// TODO: If any child exits, wait for a back-off period and then restart
-
-// TODO: Gradually increase back-off period if process fails again too quickly