Attach cron job to single cluster worker & ensure it is reassigned on crash (CC-64)

api/server.js

@@ -63,6 +63,9 @@ const corsOptions = {
   methods: [ 'GET' ],
   optionsSuccessStatus: 200,
 };
+
+let cronInitialized = false;
+
 app.use(cors(corsOptions));
 
 app.use(favicon(path.join(__dirname + '/..', 'public', 'favicon.ico')));
@@ -146,26 +149,41 @@ if (process.env.NODE_ENV === config.test.unit.env || process.env.NODE_ENV === co
   });
 } else {
   mongoose.connect(config.database.uri + config.database.db, {useNewUrlParser: true}).then((db) => {
+    let cronWorkerPID;
     if (cluster.isMaster) {
       // Fork workers
       for (let i = 0; i < numWorkers; i++) {
+        if (i === 0) {
+          const spawnedWorker = cluster.fork({START_CRON: true});
+          cronWorkerPID = spawnedWorker.process.pid;
+        } else {
           cluster.fork();
         }
+      }
       logger(`Master ${process.pid} is running. Forking ${numWorkers} workers`);
 
       // Check if worker id is died
       cluster.on('exit', (worker, code, signal) => {
         logger(`worker ${worker.process.pid} died`);
+        if (worker.process.pid === cronWorkerPID) {
+          const spawnedWorker = cluster.fork({START_CRON: true});
+          cronWorkerPID = spawnedWorker.process.pid;
+        } else {
+          cluster.fork();
+        }
       });
     } else {
       app.listen(config.port, (err) => {
-        if (err !== undefined) {
+        if (err) {
           error(`Error on startup ${err}`);
         } else {
           logger(`Worker ${process.pid} started. Listening on port ${config.port}`);
+          if (process.env.START_CRON) {
+            logger(`Attaching cronJobs to cluster worker ${process.pid}`);
             signatureCronJob.start();
             backupCronJob.start();
           }
+        }
       });
     }
   });