Setting Up a LAMP Stack with Docker Compose

Docker Compose is a tool that allows one to declare which Docker containers should run, and which relationships should exist between them. It follows the infrastructure as code approach, just like most automation software and Docker itself.

For information about installing Docker Compose, see Install Docker Compose in Docker documentation.

The docker-compose.yml File

When using Docker Compose, the Docker infrastructure must be described in a YAML file called docker-compose.yml.

Let's see an example:

In the first line we declare that we are using version 3 of the Docker compose language.

Then we have the list of services, namely the web and the mariadb services.

Let's see the properties of the services:

About Volumes

It is good practice to create volumes for:

• The , so we don't lose data when a container is created or replaced, perhaps to upgrade MariaDB.

• The directory where we put all the logs, if it is not the datadir.

• The directory containing all configuration files (for development environments), so we can edit those files with the editor installed in the host system. Normally no editor is installed in containers. In production we don't need to do this, because we can copy files from a repository located in the host system to the containers.

Note that Docker Compose variables are just placeholders for values. Compose does not support assignment, conditionals or loops.

Using Variables

In the above example you can see several variables, like ${MARIADB_VERSION}. Before executing the file, Docker Compose will replace this syntax with the MARIADB_VERSION variable.

Variables allow making Docker Compose files more re-usable: in this case, we can use any MariaDB image version without modifying the Docker Compose file.

The most common way to pass variables is to write them into a file. This has the benefit of allowing us to version the variable file along with the Docker Compose file. It uses the same syntax you would use in BASH:

For bigger setups, it could make sense to use different environment files for different services. To do so, we need to specify the file to use in the Compose file:

Docker Compose Commands

Docker Compose is operated using docker-compose. Here we'll see the most common commands. For more commands and for more information about the commands mentioned here, see the documentation.

Docker Compose assumes that the Composer file is located in the current directory and it's called docker-compose.yml. To use a different file, the -f <filename> parameter must be specified.

Docker Compose Resources and References

• in the Docker documentation.

• in the Docker documentation.

• on GitHub.

Further information about the concepts explained in this page can be found in Docker documentation:

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