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You might have read or heard that Google added PHP as a supported language to their cloud hosting platform App Engine. The official documentation is available here and gives you a lot of information to get started:
https://developers.google.com/appengine/docs/php/gettingstarted/.

If you’re a returning visitors to this blog, you’ll probably have noticed that I often work with a CMS called concrete5. It’s a neat CMS to work with for end users but also very powerful to extend for developers.

No surprise, I wanted to see if I could get concrete5 running on GAE for PHP. The documentation has clear instructions that help you to get a test environment ready on your local computer. You’ll need to install Python, PHP as well as the Google App Engine SDK for PHP, more about that here: https://developers.google.com/appengine/docs/php/gettingstarted/installing.

The Hello world tutorial explains almost everything you need to know to get concrete5 running, I’d recommend that you follow it too, it only takes you a few minutes to install everything and get the famous “hello world” output on your screen https://developers.google.com/appengine/docs/php/gettingstarted/helloworld. As you can see in this tutorial, Google doesn’t use a htaccess file but rather a file called app.yaml. This is where you specify your applications settings as well as redirect rules. The most important part is this:

- url: /.*
  script: index.php

This will tell App Engine to redirect all requests to index.php which is exactly what concrete5 does too, but normally using this:

RewriteRule . index.php [L]

However, there’s one more thing we have to take care of, there are static files that won’t be served correctly at the moment. Let’s have a look at the original .htaccess file first:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME}/index.html !-f
RewriteCond %{REQUEST_FILENAME}/index.php !-f
RewriteRule . index.php [L]
</IfModule>

Let’s just focus on the first RewriteCond, this will make sure that the RewriteRule statement is only executed if the requested file doesn’t exist. If /concrete/themes/default/main.css is requested, Apache will know that it exists as a real file and stops the rewrites process, but if /about is requested, Apache will forward that request to index.php. I couldn’t find the exact same functionality but with an additional handler, I was able to see resources like the pictures just fine. Here’s the complete content of app.yaml:

application: concrete5
version: 1
runtime: php
api_version: 1

handlers:
- url: /(.*\.(ico$|jpg$|png$|gif$|css$|js$))
  static_files: \1
  application_readable: true
- url: /.*
  script: index.php

When working on your local computer, you can easily use your existing MySQL installation but if you want to deploy your application to the cloud, things work a bit different. Unfortunately I wasn’t aware of that, I thought that if I only use very little resources, App Engine would be free. From what I can tell, you can run a PHP application for free but as soon as you want to store something in a database, you have to pay. There are two different options, first Google Cloud Storage which is a simple database without a lot of functionality, if you want to port an existing SQL based application, you might want to look at Google Cloud SQL which is a MySQL database running in the cloud. More about that here https://cloud.google.com/products/cloud-sql. Here are a few technical things that you might want to check out https://developers.google.com/appengine/docs/php/cloud-sql/developers-guide.

Since I wanted to move my concrete5 site concrete5.ch to Google App Engine, the fact that storage isn’t free, is a killer argument at the moment. I’d very much like to finish the experiment but I’ll wait till I have a project where I actually make some money before I spend money.

However, I’m pretty confident that I could get concrete5 running on App Engine.