README

Github Webhook client receiver wrappers and webservice.

Description

The Webhook Project facilitates workflow integration of Github Webhook requests. It provides class wrappers for existing projects and an optional end-point installer script for a self-contained solution that is easy to deploy.

Requirements

PHP 7.2 or higher

Usage

End-point Installer Script

The command-line script bin/add-endpoint.php creates a webservice end-point that responds to a Github Webhook for the PushEvent on a remote repository by updating a local repository and to a PingEvent by displaying a success message.

The simplest way to prepare the end-point installer is to copy this project somewhere and run Composer:

git clone https://github.com/katmore/webhook.git 
cd webhook
composer update

The installer can be invoked without any arguments; it will prompt for all the required parameters (such as the remote URL, local repo path, webhook secret, etc.):

php bin/add-endpoint.php

The --help switch will provide details on more advanced usage (such as quiet and non-interactive modes).

php bin/add-endpoint.php --help

Wrapper Classes

To use this project's wrapper classes within your existing project, the main topics of focus will be the Webhook\Request class and Payload objects. As a recomended first step, add a dependancy using Composer to your existing project:

composer require katmore/webhook

The Webhook\Request class facilitates interpreting the message body and related HTTP headers of a Github Webhook request. The Webhook\Request class constructor will instantiate and populate a Webhook\Payload child class having a class name that corresponds to the Webhook "Event Type": it searches for the existence of a class having the same "short name" as the GitHub Event Type within the namespace Webhook\Payload. If a thusly named Webhook\Payload child class is not defined for a particular event; the Webhook\Payload\Event class is used by default. For example, a Webhook\Payload\PushEvent object is created and populated for a PushEvent Webhook request.

The Payload object as populated by the Webhook\Request constructor is available using the Webhook\Request::getPayload() method as detailed in the example below:

/*
 * the 'Secret' field corresponding to the expected Webhook request
 */
$hubSecret = "My Secret";

/*
 * obtain the messageBody; in this case, by reading from the php input stream
 */
$messageBody = file_get_contents('php://input');

/*
 * obtain the 'hubSignature'; for example, from the value of the HTTP header 'HTTP_X_HUB_SIGNATURE'
 */
$hubSignature = $_SERVER['HTTP_X_HUB_SIGNATURE'];

/*
 * obtain the 'gitHubEvent'; for example, from the value of the HTTP header 'HTTP_X_GITHUB_EVENT'
 */
$gitHubEvent = $_SERVER['HTTP_X_GITHUB_EVENT'];

/*
 * instiantate a Webhook\Request object...
 */
$request = new \Webhook\Request($messageBody, $hubSignature, $gitHubEvent);

/*
 * validate the request signature
 */
$request->validateSignature($hubSecret);

/*
 * get the payload object...
 * For more info on payloads for the various github events, see:
 *    https://developer.github.com/v3/activity/events/types
 */
$payload = $request->getPayload();

/*
 * The payload object will be an instance of the 
 *    \Webhook\Payload\PushEvent class
 *    if the github event was a 'Push Event'.
 *  
 * The payload object will be an instance of the 
 *    \Webhook\Payload\PingEvent class
 *    if the github event was a 'Ping Event'.
 *
 * The payload object will be an instance of the 
 *    \Webhook\Payload\Event class
 *    for all other events.
 */
var_dump($payload);

Validating a request's "Hub Signature"

At some point in the handling of a Webhook request it is critical that the "Hub Signature" be validated against the shared "Secret" for obvious security reasons. The end-point installer and end-point example both accomplish this by using the Request::validateSignature() method of the Webhook\Request class.

/*
 * the 'Secret' field corresponding to the expected Webhook request
 */
$hubSecret = "My Secret";

/*
 * obtain the messageBody, hubSignature, and gitHubEvent
 */
$messageBody = file_get_contents('php://input');
$hubSignature = $_SERVER['HTTP_X_HUB_SIGNATURE'];
$gitHubEvent = $_SERVER['HTTP_X_GITHUB_EVENT'];

/*
 * instiantate a 'Request' object...
 */
$request = new \Webhook\Request($messageBody, $hubSignature, $gitHubEvent);

try {
  /*
   * validate the request signature
   */
  $request->validateSignature($hubSecret);
} catch(\Webhook\InvalidRequest $e) {
   /*
    * force a 500 HTTP response code upon encountering an 'InvalidRequest' exception,
    */
   http_response_code(500);
   echo "Invalid Request: ".$e->getMessage();
   return;
}

/*
 * continue to do more things...
 */
//$payload = $request->getPayload();

Using the provided end-point example

An end-point example is provided at web/endpoint-example.php which responds to a PushEvent by invoking a 'git pull' or any custom code placed in a callback function, as configured. It also responds to a a PingEvent with a success message.

copy the provided web/endpoint-example.php...

cp web/endpoint-example.php web/my-repo-endpoint.php

edit to specify configuration...

change the value of $config['RepoUrl'] to your GitHub repository URL:

$config['RepoUrl'] = 'https://github.com/my-organization/my-repo';

change the value of $config['Secret'] to the "Secret" configured in Github for the webhook:

$config['Secret'] = 'My Secret';

leave the value of $config['RepoPath'] empty to skip the repo update, or change it to the local system path of a repository to perform a git update on every 'push' Webhook event:

$config['RepoPath'] = '';
//$config['RepoPath'] = '/path/to/my/repo';

place any custom code within the onPushEvent function that should be executed on every 'push' Webhook event

function onPushEvent(Payload\PushEvent $payload) {
    /*
     *
     * --- place code in this function --
     * --- that should execute when a Github 'push' event occurs --
     *
     */
     //
     // place your custom code here
     //
}

Unit Tests

coverage.txt: unit test coverage report
phpunit.xml: PHPUnit configuration file
tests/phpunit: source code for unit tests

To perform unit tests, execute phpunit located in the vendor/bin directory.

vendor/bin/phpunit

The tests.sh wrapper script is provided for convenience.

./tests.sh

Legal

"Webhook" is distributed under the terms of the MIT license or the GPLv3 license.

katmore / webhook

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