Upgrade Drupal to PHP 8: Compiling extensions

In the last article, we discussed the changes required to get Drupal 9.1 running on PHP 8. At that time, we got the Drupal 9.1 dev release working on PHP 8.0.0 RC4 with a few patches. Since then, a lot has changed with many of those patches being committed and Drupal 9.2 dev open for development. But we’ll talk about all of that at a later date. Today, let’s look at getting some of the common PHP extensions and configure it to run with Drupal.

We left off at a point where we have plain Drupal 9.1 running on a plain PHP 8 RC4 setup. Drupal doesn’t require any extensions, not in PHP core, and that means we only had to enable extensions like gd, MySQL, and others to have Drupal 9.1 running. With that, we were able to install Umami and use the site without any problems at all. To enable those extensions, we only needed our docker-php-ext-enable script, which is part of the PHP base Docker image. See the Dockerfile in the reference repository for the source code (lines 41-52). Installing other extensions that are not part of the PHP core is not quite that simple. Think of it this way: if a module is present in Drupal core, you can install it right after downloading Drupal. But if it is a contrib module, you have to download and install it separately. It’s the same thing with PHP extensions.

Why test with extensions?

Just as you probably wouldn’t have a Drupal site with at least one contrib module, you probably wouldn’t have a PHP installation without a few of the common extensions. Drupal core utilizes some of these extensions when they are available (such as APCu and YAML), which yields better performance. This means that even though the extensions are not technically required, you would most likely have them.

I started with extensions, which I almost always install on sites I work. These are APCu, YAML, and Redis. Drupal core doesn’t use Redis, but I almost always install the Redis module for caching, which requires this module. It made sense to test if it worked on PHP 8 (both the module and the extension). As for the other two extensions, Drupal core uses APCu and YAML extensions for better performance if they are available. Again, it is a good idea to test Drupal with these extensions installed.

Installing extensions

Typically, we would use PECL to install any extensions we needed. PECL is a repository for PHP extensions, very much like a composer for PHP packages. With PECL, we would just need to run a command such as pecl install Redis to install the extension. You can see this being used in lines 53-58 in the Dockerfile.

pecl install apcu redis yaml

This is not as simple with PHP 8. PHP 7.4 removed default support for PECL and the official Docker image removed the command in PHP 8 images (it applied an explicit option to keep it for PHP 7.4).

Alternative tool to build extensions

I found another tool called pickle, which was intended to replace PECL but became dormant as well. I noticed some activity on the project, including a relatively recent release, and I tried that first.

The tool worked very well for APCu and Redis extensions. However, for YAML, it failed because it could not parse YAML's beta version number (2.2.0b2). I found that this was fixed in a recent commit but that would have meant that I would need to build pickle in my Docker image rather than just downloading and using it. I was not looking to go that route.

Building the extension manually

This left me with only one option: building the extensions myself. Fortunately, this turned out to be much simpler than I thought. You can see the steps required for each extension in lines 54-67 in the reference repository’s Dockerfile. For each extension, there are essentially just two steps:

1. Clone their source code of the extension
2. Run phpize, make, and make install to build the extension

We need the PHP source available to use the above tools and this is easily achieved using a helper script in the Docker image. You can see it being used in line 39 in the reference repository. Once we build the extensions, we clean up the PHP source to keep our Docker image size small. This is what the complete step looks like:

docker-php-source extract;
git clone https://github.com/krakjoe/apcu.git; cd apcu;
phpize; make; make install; cd ..;
# ... Install other extensions same way
docker-php-source delete;

Enabling extensions

Now that the extensions are installed, we can use the same script (docker-php-ext-enable) as earlier to enable the extensions. In our reference repository, you can see this done on lines 69-72. Thanks to these helper scripts, we now have our extensions enabled and configured for both the PHP module (for Apache) and the CLI. This can be verified by running the following command:

php -m

The above command will list all the enabled PHP extensions (internal ones as well) and you should be able to find apcu, redis, and yaml in the list.

Bringing it together

Now, we need to make sure that Drupal works with the above extensions. Since APCu and YAML extensions are used by the core, we should see any issues immediately. We can even verify that Redis is connected and APCu is being used by looking at the status report page, as shown in the following screenshot. 

For Redis, we need to install the Drupal module as well as the Drupal core doesn’t use it directly. We will discuss installing modules in another post.

PHP 8 remains an important milestone in PHP history, not just because of cool new features but also because it established a trusted release cycle promised at the release of PHP 7. A predictable release cycle helps build trust and also consistently brings new features and innovation to the product. We saw that with Drupal 8’s regular six-monthly release cycle and we will see that with PHP as well.