Support UNIX domain socket for streaming service without using PORT (#8217)

* Support UNIX domain socket for streaming service without using PORT

The use of UNIX domain socket for streaming service was not officially supported,
but it was made unofficial to use by setting a path to PORT.
From now on, SOCKET will be used just like setting for puma.

* Hundle relative path

streaming/index.js

@@ -9,6 +9,7 @@ const log = require('npmlog');
 const url = require('url');
 const WebSocket = require('uws');
 const uuid = require('uuid');
+const fs = require('fs');
 
 const env = process.env.NODE_ENV || 'development';
 
@@ -70,6 +71,9 @@ const redisUrlToClient = (defaultConfig, redisUrl) => {
 const numWorkers = +process.env.STREAMING_CLUSTER_NUM || (env === 'development' ? 1 : Math.max(os.cpus().length - 1, 1));
 
 const startMaster = () => {
+  if (!process.env.SOCKET && process.env.PORT && isNaN(+process.env.PORT)) {
+    log.warn('UNIX domain socket is now supported by using SOCKET. Please migrate from PORT hack.');
+  }
   log.info(`Starting streaming API server master with ${numWorkers} workers`);
 };
 
@@ -574,9 +578,16 @@ const startWorker = (workerId) => {
     });
   }, 30000);
 
-  server.listen(process.env.PORT || 4000, process.env.BIND || '0.0.0.0', () => {
+  if (process.env.SOCKET || process.env.PORT && isNaN(+process.env.PORT)) {
+    server.listen(process.env.SOCKET || process.env.PORT, () => {
+      fs.chmodSync(server.address(), 0o666);
+      log.info(`Worker ${workerId} now listening on ${server.address()}`);
+    });
+  } else {
+    server.listen(+process.env.PORT || 4000, process.env.BIND || '0.0.0.0', () => {
       log.info(`Worker ${workerId} now listening on ${server.address().address}:${server.address().port}`);
     });
+  }
 
   const onExit = () => {
     log.info(`Worker ${workerId} exiting, bye bye`);