In traditional WordPress installations, wp-config.php often contains sensitive information, such as database credentials and secret keys. These details are typically hardcoded, making them vulnerable to exposure, especially if the configuration file is improperly managed or ends up in version control.
However, a Docker-based WordPress setup introduces a more secure and modular approach: the use of environment variables. The getenv_docker() function is a prime example of this improved practice.
Understanding getenv_docker()
getenv_docker() is not a standard PHP function but a custom wrapper used within the Docker environment. Its purpose is to abstract the environment variable retrieval process, allowing the application to fetch configuration details such as database passwords and unique authentication keys from the environment in which the Docker container runs, rather than from the file system.
How getenv_docker() Enhances Security
Environment variables are ephemeral and exist only in the context of the running Docker container. They do not persist in the codebase and can be easily changed without modifying the code. This means that if your source code is exposed, the credentials remain secure.
Furthermore, environment variables can be set in various secure places, like a CI/CD pipeline, Docker Swarm secrets, Kubernetes secrets, or even a .env file that is not checked into source control.
Using getenv_docker() in wp-config.php
Within wp-config.php, the getenv_docker() function is used to fetch environment variables:
define('DB_PASSWORD', getenv_docker('WORDPRESS_DB_PASSWORD', 'example_password'));
In this example, the getenv_docker() function attempts to get the value of an environment variable named WORDPRESS_DB_PASSWORD. If it's not found, it falls back to 'example_password'.
Setting Environment Variables for Docker
When you run a Docker container, you can pass environment variables using the -e flag or an env_file:
docker run -e WORDPRESS_DB_PASSWORD=your_strong_password wordpress
Or for multiple variables, you can use an env_file:
docker run --env-file wordpress.env wordpress
Conclusion
Leveraging getenv_docker() for environment variable management aligns with the Twelve-Factor App methodology, enhancing security and configuration management in your WordPress deployment. By externalizing configuration details, Docker makes it easier to keep sensitive information out of the codebase, reducing the risk of security breaches and simplifying the process of updating configurations.