WordPress is one of the most popular content management software (CMS) due to its multitude of features and ease of use. However setting up a new web host environment can be time consuming especially if you need to do it often. Docker Compose manages to simplify the installation process to a single deployment command greatly reducing the time and effort required. Deploying WordPress with Docker Compose is fast and easy after the first time setup.

WordPress using Docker Compose

Docker is a container platform that allows simple and fast software installations on any system or OS. It wraps the piece of software in a complete file system that includes everything it needs to run such as code, runtime, system tools and libraries. This allows anyone to package an application with its dependencies into a standardized building block.

Install Docker

Using Docker Compose requires to have the Docker daemon running on your cloud server. Installing Docker itself is already easy. Firstly run the usual update command for your system to make sure you have the latest source lists.

# Debian and Ubuntu
sudo apt-get update
# CentOS
sudo yum update

Check that you have the curl command line utility.

curl -V

It comes preinstalled with most Linux distributions, but if it can not be found, install it manually with the appropriate command for your OS.

# Debian and Ubuntu
sudo apt-get install curl
# CentOS
sudo yum install curl

Use the command below to download and install Docker. The process requires root privileges so you will be asked for your sudo password on any non-root user.

curl -fsSL https://get.docker.com/ | sh

Towards the end of the installation process you will see a suggestion to add your username to the Docker users group. Doing this allows you to run Docker commands without needing to invoke sudo every time.

sudo usermod -aG docker <username>

Log out and back in again after adding yourself to the Docker users group before continuing.

You can check that the installation was successful with the following test program:

docker run hello-world

You should see an output similar to the example below.

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
...
Hello from Docker.
This message shows that your installation appears to be working correctly.
...

If the command does not work immediately, restart the Docker service with the following and try to run the hello-world app again.

sudo service docker restart

Docker should now be installed and working correctly. Continue on below with rest of the guide to install Docker Compose.

Install Docker Compose

While installing applications in containers with simple commands is already easy enough, it still requires memorizing those commands and their parameters. Docker-compose allows combining the install process for multiple containers. Install the additional components for Docker using the procedure below.

First temporarily switch to your root account.

sudo -i

Use the install script below to download and apply the docker-compose packet.

curl -L https://github.com/docker/compose/releases/download/1.6.0/docker-compose-`uname -s`-`uname -m` > /usr/local/bin/docker-compose

Set the execution permissions to it with:

chmod +x /usr/local/bin/docker-compose

And then exit the root user account to return to your normal username.

exit

You should now have the docker-compose application installed and available, test it by checking for the version number.

docker-compose -v
docker-compose version 1.6.0, build d99cad6

With the Docker Compose installed you are now ready to start configuring your containerized WordPress environment.

Configuring WordPress with compose

WordPress is officially available on Docker Hub and easy to setup, but it will not create a working website by itself, it requires a database to store the content. MariaDB is a community-developed relational database management system and a drop-in replacement for MySQL. It is also officially available on Docker and provides easy instructions with up to date images.

Setting up containers with Docker Compose works by creating a Dockerfile and docker-compose.yml in the desired working directory. Start off by creating your working directory, e.g. wordpress-compose.

mkdir  ~/wordpress-compose && cd ~/wordpress-compose

Create a Dockerfile with your favourite text editor, for example with nano:

nano Dockerfile

Then add the lines below to the file, save and exit. This tells Docker how to build an image defining a container with PHP and WordPress.

FROM orchardup/php5
ADD . /code

Next create the docker-compose.yml -file that will tell Docker how to start the WordPress and MariaDB containers.

nano docker-compose.yml

Copy in the segments from the example underneath and set the parameters in the file. Replace the database <password> and <server public IP> with values appropriate to your cloud server. Make sure the password is the same for both environment variables so that WordPress will be able to access the database.

wordpress:
    image: wordpress
    links:
     - mariadb:mysql
    environment:
     - WORDPRESS_DB_PASSWORD=<password>
    ports:
     - "<server public IP>:80:80"
    volumes:
     - ./code:/code
     - ./html:/var/www/html
mariadb:
    image: mariadb
    environment:
     - MYSQL_ROOT_PASSWORD=<password>
     - MYSQL_DATABASE=wordpress
    volumes:
     - ./database:/var/lib/mysql

When you are done editing the compose -file, save it and exit the editor.

Now create the new containers with command below. This starts both containers on the background and leaves them running. If you wish to see the output from the containers just leave out the -d to deploy the applications on the foreground.

docker-compose up -d

You can then open the public IP or domain of your WordPress server in your web browser to test the installation. You should be redirected to the WordPress initial setup page like the image shown below.

WordPress initial setup page

If you want to make changes to the configuration, simply update the files and run the docker-compose -command again. If docker-compose detects the configuration or the image has changed since the container was created, it applies the changes by stopping and recreating the containers while preserving mounted volumes.

For example you can check for updates on the WordPress and MariaDB images and push changes to your containers using the commands below.

docker-compose pull
docker-compose up -d

Other useful commands for docker-compose are start/stop, config, ps and down.

# Starts all stopped containers in the work directory
docker-compose start
# Stops all currently running containers in the work directory
docker-compose stop
# Validates and shows the configuration
docker-compose config
# Lists all running containers in the work directory
docker-compose ps
# Stops and removes all containers in the work directory
docker-compose down

The docker-compose module also has its own command-line reference guide at their documentation page.

Conclusions

Congratulations, you should now have a docker-compose setup for WordPress and MariaDB running in containers and an easy way to update the services when needed. While manually running Docker commands to create containers already simplifies application management, docker-compose takes it a step further and allows you to bundle multiple containers within a single working directory.

Before continuing on building your new WordPress site, make sure to pay attention to the security on your server. To find out more, check out our article for How To Secure Your Linux Cloud Server.