Add node cluster library

src/server.js

-const debug = require('debug')('node-express-base');
-
+const debug = require('debug')('simcaq-api');
 const libs = `${process.cwd()}/libs`;
-
 const config = require(`${libs}/config`);
-
 const log = require(`${libs}/log`)(module);
-
 const app = require(`${libs}/app`);
-
 const compatVersion = require(`${libs}/middlewares/checkVersion`);
+const cluster = require('cluster');
 
 // Check if Node version is compatible
 if (!compatVersion()) {
     process.exit(1);
 }
 
-// Set default port: first environment variable PORT, then configuration and last 3000
-app.set('port', process.env.PORT || config.port || 3000);
-process.env.NODE_ENV = process.env.NODE_ENV || 'development';
-// Set default ip: first environment variable IOP, then configuration and last '127.0.0.1'
-app.set('ip', process.env.IP || config.ip || '127.0.0.1');
-
-const server = app.listen(app.get('port'), () => {
-    log.info(`Express server listening on port ${server.address().port}`);
-});
-
-// For testing
-module.exports = server;
+if(cluster.isMaster) {
+    log.info(`Master ${process.pid} is running`);
+
+    const numCPUs = require('os').cpus().length;
+    for(let i=0; i < numCPUs; ++i) {
+        cluster.fork();
+    }
+
+    // Caso uma instâcia morra
+    cluster.on('exit',  (worker, code, signal) => {
+        log.info(`Worker ${worker.process.pid} died`);
+        // Revive a instância
+        cluster.fork();
+    });
+} else {
+    // Set default port: first environment variable PORT, then configuration and last 3000
+    app.set('port', process.env.PORT || config.port || 3000);
+    process.env.NODE_ENV = process.env.NODE_ENV || 'development';
+    // Set default ip: first environment variable IOP, then configuration and last '127.0.0.1'
+    app.set('ip', process.env.IP || config.ip || '127.0.0.1');
+
+    const server = app.listen(app.get('port'), () => {
+        log.info(`Express server listening on port ${server.address().port}`);
+    });
+    
+    log.info(`Worker ${cluster.worker.id} is running`);
+
+    // For testing
+    module.exports = server;
+}