In a previous post I covered one method you can use to secure the credentials in your PHP application. In that article I provided an example specific to the use of Apache and its envvars handling to read in values and pass them along to the waiting PHP process as $_ENV variables. This in combination with the psecio/secure_dotenv library allowed you to pass along an encryption key that could be used to decrypt values from the application's .env file.
While this works for a flat Apache and PHP environment, the world has moved beyond that basic setup and has moved to using another popular environment building tool: Docker. [...] So, if we move forward with current technology, we need a way to secure our credentials in a Docker-based environment that makes use of PHP-FPM and Nginx. Fortunately there's a relatively simple way to handle this with just a few configuration changes.
The tutorial starts with an overview of what technologies are involved in the environment (Docker, PHP-FPM, Nginx and Vault) and some of the options for storing secrets with Docker. It then gets into the configuration files needed to create the environment: a Docker Composer configuration, the Nginx server definition, the PHP-FPM settings and the
.env file that contains the secrets. Using these pieces and some special configuration directives, the secrets are injected into Docker when the containers are built and storing them in-memory rather that on disk.