Deploying Automatically using WebHooks


Time is precious. Automate your processes.


Imagine you have a server running a website and you want to deploy a bunch of changes that you pushed to your GitHub repository. Ok… instead of login into the server and execute some commands to pull the changes, you can just setup a WebHook.

Webhooks allow you to build or set up integrations which subscribe to certain events on GitHub.com. When one of those events is triggered, we’ll send a HTTP POST payload to the webhook’s configured URL.

Sounds simple and it is. I will use Node.js to interpret the triggered event from the repository (POST payload). Let’s get started.


Node.js

(If your server don’t have Node.js: Installing Node.js via package manager)

Installation

$ [sudo] apt-get install --yes nodejs

Initialise

$ [sudo] npm install npm -g

$ mkdir webhook
$ cd webhook

$ npm init

This command will prompt for a number of things such as the name and version of your application. For now, you can simply hit RETURN to accept the defaults for most of them.

We also need to install some dependencies.

$ npm install express -s
$ npm install shelljs -s

After that, if your choice for entry point: (index.js) was the default value then you need to create the file index.js with your preferred text editor.

I decided to run git pull when the server receives an event:

var express = require('express');
var app = express();
var sh = require('shelljs');

app.get('/', function (req, res) {
  res.send('WebHook Receiver');
});

// Accept POST request
app.post('/run', function (req, res) {
  res.send('Request accepted');
  sh.exec('cd /path/to/www; git pull', function(code, output) {
    console.log('Exit code:', code);
    console.log('Program output:', output);
  });
});

var server = app.listen(4000, function () {
  var port = server.address().port;
  console.log('Listening at port: %s', port);
});

Finally, we can run the WebHook Receiver forever and ever:

$ [sudo] npm install forever -g

$ forever start index.js

# You can check if it's running
$ forever logs


GitHub Settings

Now go to your repository settings -> Webhooks & services -> Add webhook and assign the Payload URL with your server, for example: http://x.x.x.x:4000/run. Done.

Please consider securing your webhooks.


Best,

Ricardo Pereira



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