Understanding WordPress Docker Setup and User Permissions

If you’ve started developing your website on WordPress, you may be using Docker. Docker is a software platform that can launch your website in an isolated environment known as a container. This way, your WordPress site will run consistently, regardless of where you deploy your website. Today, I’ll explain a common challenge which many of us run into that involves Docker, user permissions, and your WordPress files.

The Problem with User Permissions

When using Docker with WordPress, a common hiccup many developers come across involves user permissions, which control who can read, write, and execute your files.

Imagine in your setup, Docker is executing scripts, like creating files and folders, which only it can modify. This becomes a concern because your WordPress application, which runs under the www-data user, also needs to upload files, update plugins, or write logs. Unfortunately, since Docker is the owner of your folders and files, www-data can’t make changes leading to errors or misbehavior on your site.

First Solution: Modifying Your Entrypoint Script

To solve the problem of permissions, one method involves modifying the entrypoint.sh script, which is a file that your Docker uses to execute processes when starting your container. For this method, we will write a script that corrects file permissions and then execute Docker’s default operations.

Here’s a sample of the entrypoint.sh script:

!/bin/bash

echo Fixing permissions…
chown -R www-data:www-data /var/www/html/wp-content/
docker-entrypoint.sh apache2-foreground

In this example, chown -R www-data:www-data /var/www/html/wp-content/ is a command that changes the owner of /var/www/html/wp-content/ directory (where WordPress stores your content) to www-data. Now your WordPress application can make changes to its own files.

Second Solution: Creating a Custom Entrypoint Script with Delayed Commands

Another method introduces a time delay before setting file permissions. This might be necessary as Docker might overwrite your changes during startup.

Here’s how you create your own custom entrypoint.sh script with a time delay:

In 10 seconds set the ownership

$(sleep 10 && chown -R www-data:www-data /var/www/html/) &

Run the parent’s ENTRYPOINT and CMD as defined

docker-entrypoint.sh apache2-foreground

With this script, Docker will wait for 10 seconds before setting ownership. By doing so, your command would have enough delay to avoid being overwritten by Docker at startup.

A point of caution when using this method, however, is that if your Docker script changes (e.g., a software update), you need to review it to make sure your solution will still work.

Which One Should Be Used

Both methods stated above will solve the permission issue, but they have different use cases. The first method is handy if you are sure Docker won’t overwrite your commands at startup, while the second method is a fail-safe if Docker does modify files after your script is executed. Carefully consider the behavior of your system before applying the right solution.

Remember, it’s your journey to creating a wonderful WordPress site. Keep solving challenges, keep learning, and keep creating!