Running WordPress on Docker

Similar to the previous post, Running Joomla on Docker, I was interested in spinning up a temporary WordPress installation so that I could target it with various scanning and reconnaissance tools. There is an official WordPress Docker image at https://hub.docker.com/_/wordpress/.

The steps were more-or-less the same. Note that if you followed the steps in the previous post, you will likely want to stop and remove the existing MySQL container before attempting to start a new one with the same name:

docker stop some-mysql
docker rm some-mysql

Start the MySQL Docker container:

docker run --name some-mysql -e MYSQL_ROOT_PASSWORD=passW0rd -e MYSQL_DATABASE=wordpress -e MYSQL_USER=wordpress -e MYSQL_PASSWORD=wpP455 -d mysql:5

Start the WordPress Docker container:

docker run --name some-wordpress --link some-mysql:mysql -e WORDPRESS_DB_HOST=172.17.0.2 -e WORDPRESS_DB_USER=wordpress -e WORDPRESS_DB_PASSWORD=wpP455 -e WORDPRESS_DB_NAME=wordpress -p 8080:80 -d wordpress

I was then able to visit http://localhost:8080 and complete the web-based setup tasks.

Note that the MySQL container, as launched, does not have any shared volumes. Everything stored there is ephemeral and will be lost if the container is removed. To my surprise, however, the content survived stopping and restarting the container. The volumes for each container are located in the following directory:

/var/lib/docker/volumes/

Using docker inspect some-wordpress I could see that there was a mounted volume at:

/var/lib/docker/volumes/be3d54591da609e911a1ec3f0615a564990b37da184a67fab0ac0e75cc711c7f/_data

Indeed, the usual WordPress files, such as wp-config.php, were located there.

I did the same for the MySQL container and found the .frm and .ibd files for each of the tables in the WordPress database.

These files persist when the container is stopped, and persist even when the container is removed! In fact, when I removed all containers, I discovered there were still 22 volumes in /var/lib/docker/volumes from previous container projects and experiments.

The command to view these volumes is:

docker volume ls

To remove unused volumes, use:

docker volume prune

Container volumes are not as ephemeral as I originally thought!