Automatic website publishing with Git, GitHub-Style

The web server at work is a Windows 2008 R2 machine running a WAMP stack to serve the (mostly static) sites. Each hosted subsite is configured a vhost and is stored in its own subfolder on disk. Apache is being run as a separate user which has limited access to the filesystem.

<VirtualHost *:80>
    ServerName subdomain.ikdoeict.be
    UseCanonicalName On
    DocumentRoot "c:/apache2/htdocs/vhosts/subdomain.ikdoeict.be/wwwroot"
    php_admin_value open_basedir "c:/apache2/htdocs/vhosts/subdomain.ikdoeict.be;c:/php/temp"
</VirtualHost>

Next to the web server we also have a private Git server running Linux to/from wich code is pushed/pulled. Repositories are accessible via HTTPS and authenticating to this server is done via an HTTP Username & Password (not via a SSH key).

Install Git on the Web Server

As it’s a Windows server I’ve installed Git for Windows, choosing to run Git and the Unix Tools from the Windows Command Prompt.

Once installed, I’ve restarted the server to get the git command available anywhere on the server.

Create new repository on the Git server

Create a (bare) repository on the Git server and make sure that is externally accessible so that you can clone it on an other machine.

Clone, Branch & Develop on your local machine

Develop your site on your machine as you’d normally do (in my case: on the master branch).

git clone https://user@gitserver/project.git .
[build site]
git add .
git commit -m 'the one true commit'
git push origin master

Also create a gh-pages branch which will be the version to be deployed to the web server.

git branch gh-pages
git checkout gh-pages
[make changes, such as adding a Google Analytics Tracking Code]
git add .
git commit -m 'changes for online version'
git push origin gh-pages

Clone on the Web Server

On the web server, clone the project into the vhost’s DocumentRoot and activate the gh-pages branch so that the web server will serve that version.

cd c:/apache2/htdocs/vhosts/subdomain.ikdoeict.be/wwwroot
git clone https://user@gitserver/project.git -b gh-pages .

git branch -f gh-pages origin/gh-pages
git checkout gh-pages
git branch -d master

Be sure to verify with your favorite text editor that you’ve got the correct version. If it’s correct you’ve successfully deployed your site onto the web server. Break out the champagne, but don’t open it yet, we’ve got some more work to do.

Security Alert!

You might not know this but whenever you clone a Git project onto disk, you’ll end up with a (hidden) .git directory in the root of your project. In that directory, everything about the repository clone is stored: commits, branches, hooks, ignore files, remotes, etc.

Now that you’ve deployed the project onto the web server, that .git directory will also be present in your vhost DocumentRoot, meaning that it — and its files — are now publicly accessible via http://subdomain.ikdoeict.be/.git/

To prevent this adjust your apache config to disallow the .git folder from being accessed over HTTP.

<VirtualHost *:80>
    ServerName student.ikdoeict.be
    UseCanonicalName On
    DocumentRoot "c:/apache/htdocs/vhosts/student.ikdoeict.be/wwwroot"
    php_admin_value open_basedir "c:/apache/htdocs/vhosts/student.ikdoeict.be;c:/php/temp"
    
    <Directory "c:/apache/htdocs/vhosts/student.ikdoeict.be/wwwroot/.git">
        Order allow,deny
        Deny from all
    </Directory>
    
</VirtualHost>

Deploying changes

Now, how to get changes onto the web server? Make changes on your local machine as you’d normally do, and push them upstream when commited. Be sure to merge your changes in the gh-pages branch as that’s the version that’s served on the web server.

git checkout master
[make changes]
git add .
git commit -m 'changes'
git push origin master
	
git checkout gh-pages
git merge master
git push origin gh-pages

On the web server, do a git pull to get the latest version

git pull origin gh-pages

Prerequisite: “standalone” git pull

In order to automate deployment, git pull should run fine without any user intervention such as requiring to enter a password.

As our setup requires HTTP username + password authentication it’ll ask for the password each time I push/pull something. In order to bypass this edit .git/config so that the remote url contains the password. If you’re doing a fresh clone, you can clone the repository as https://user:pass@gitserver/project.git straightaway.

PHP, do your thing!

Up until now we can deploy changes onto the server, yet it still requires us to log in to the server and manually invoke a git pull. What if we could just open up a webpage in our browser which does the updating for us?

Luckily for us, PHP has a built-in command shell_exec, which allows you to execute a command via the shell and which returns the output. Given this, it’s fairly easy to knock up a PHP script that executes a git pull

<php
    echo nl2br(shell_exec('git pull origin gh-pages 2>&1'));

Add this file on your local machine to your gh-pages branch …

git checkout gh-pages
[create update.php]
git add .
git commit -m 'update script'
git push origin gh-pages

… and — for the final time — do a manual git pull on the web server.

git pull origin gh-pages

Once the file is on the web server, you can from then on update the version on the server by visiting http://subdomain.ikdoeict.be/update.php. The file will give output when done.

Putting the magic in automagic

Deploying new versions goes smooth by now, but it’s not fully automated … yet.

You might not know this but Git supports hooks. Hooks are executed after a certain action is performed and are stored in .git/hooks/. For example: after a commit, you could let a hook send out a tweet with your commit message.

One of the hooks that’s interesting for us is the post-receive hook, a server-side hook which is executed after a client has performed a push. We can take this hook, and let it call the update.php script for us. This way, we just have to push, and the web server will be updated automagically.

First, create the hook by renaming the sample provided

cd .git/hooks/
mv post-receive.sample post-receive
chmod +x post-receive

Second — and most important — adjust the hook’s content so that it calls the update.php script

#!/bin/sh
curl -s http://subdomain.ikdoeict.be/update.php

Happy deploying!