From 7c34463cc4083932bd52d2ae8cbcba866bd2e12a Mon Sep 17 00:00:00 2001
From: Jeffrey Sun <jrsun@mit.edu>
Date: Tue, 2 May 2017 14:05:02 -0700
Subject: [PATCH] use express-cluster for drop-in cluster support

---
 package.json |  1 +
 server.js    | 42 +++++++++++++++++++++++-------------------
 2 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/package.json b/package.json
index bf00d49..3fed837 100644
--- a/package.json
+++ b/package.json
@@ -20,6 +20,7 @@
     "canvas": "^1.6.2",
     "chance": "^1.0.4",
     "express": "^4.14.0",
+    "express-cluster": "0.0.4",
     "newrelic": "^1.35.1",
     "node-gyp": "^3.4.0",
     "sanitize-filename": "^1.6.1",
diff --git a/server.js b/server.js
index dcea871..89db84a 100644
--- a/server.js
+++ b/server.js
@@ -5,6 +5,7 @@ try {
 }
 
 const express = require('express');
+const cluster = require('express-cluster');
 const uuid = require('uuid/v4');
 const sanitize = require('sanitize-filename');
 const Canvas = require('canvas');
@@ -20,26 +21,29 @@ function composeImage(width, height, seed) {
     return canvas;
 };
 
-const app = express();
-
 const cacheTimeout = 60 * 60 * 24 * 30;
 
-app.get('/healthcheck', (req, res) => {
-    res.status(200).end();
-});
+cluster((worker) => {
+    const app = express();
 
-app.get('/:width/:seed', (req, res) => {
-    let width = parseInt(req.params.width) || 400;
-    if (width > 400) width = 400;
-    const seed = sanitize(req.params.seed) || uuid();
-    const canvas = composeImage(width, width, seed);
-    const buffer = canvas.toBuffer();
-    res.set('Cache-Control', 'max-age=' + cacheTimeout);
-    res.set('Content-length', buffer.length);
-    res.type('png');
-    res.end(buffer, 'binary');
-});
+    app.get('/healthcheck', (req, res) => {
+        res.status(200).end();
+    });
 
-app.listen(process.env.PORT || 3000, () => {
-    console.log('listening on http://localhost:3000');
-});
+    app.get('/:width/:seed', (req, res) => {
+        let width = parseInt(req.params.width) || 400;
+        if (width > 400) width = 400;
+        const seed = sanitize(req.params.seed) || uuid();
+        const canvas = composeImage(width, width, seed);
+        const buffer = canvas.toBuffer();
+        res.set('Cache-Control', 'max-age=' + cacheTimeout);
+        res.set('Content-length', buffer.length);
+        res.type('png');
+        res.end(buffer, 'binary');
+    });
+
+    activePort = process.env.PORT || 3000;
+    app.listen(activePort, () => {
+        console.log('worker ' + worker.id + ' is listening on port ' + activePort);
+    });
+})