Docker + WordPress Setup

Outcome

At the end of this tutorial you will have set up a full WordPress environment on your computer with Docker. This local dev. environment will allow you to install themes and plugins with ease, as well as develop your own new themes (or plugins). You will be able to access everything in a regular browser just like a live website.

Summary

Docker is a software container platform that whisks away all of the complexities of setting up a local development environment into a neatly packaged application. It truly is contained — no “running around” to various places installing databases, obscure supporting packages and so forth. This is no small accomplishment if you remember what it used to be like to try to mimic a web server setup on your local computer. My one grievance with Docker is there seems to be different ways to do the same thing which makes it confusing to learn at first.

For that reason I put together this tutorial on how I setup a local development environment (on a Mac) with Docker for building a WordPress theme. I’ll walk you through how to install WordPress (including a MySQL database, all via Docker) and setup your “wp-content” folder so you can work with actual theme files and plugins.

tldr

The resulting code is on GitHub for reference.

1 Install Docker

Download and install the Docker Community Edition for Mac like you would any other application. This version of Docker includes Docker Compose which we’ll need for our WordPress setup.

2 Start Docker

Once Docker is installed, start the application. There will be a prompt for your system password, enter it and after it runs through a few more steps automatically you’ll see Docker running in the toolbar menu in the upper right of your screen. It’s a whale ship carrying cargo, clever little icon.

3 Create New Directory

Now it’s time to setup the directory in which we’ll build our WordPress theme. Create a new folder wherever you want and name it whatever you want. I named mine docker-wordpress-theme-setup to match the GitHub repository. We’ll set up our entire WordPress ecosystem in this directory.

4 docker-compose.yml

For the rest of the tutorial I’m assuming you have some familiarity with Terminal and have a favorite code editor. However, I’ll still call out the Terminal commands explicitly to do my best to make sure no one gets lost along the way.

Open your code editor, create a blank file named docker-compose.yml and save it in the directory you created in Section 3. This is the file Docker will use to set up WordPress and the MySQL database.

Open Terminal. When you start Terminal the blank screen will likely be in your home directory. Just in case type the command below and hit ‘return’:

cd ~

The cd command means “change directory” and the tilde is a shortcut to the home directory. So now you’re located in your home directory. Next we need to navigate to the directory we created in Section 3. For me, I type:

cd docker-wordpress-theme-setup

Once there, type ls and you should see your docker-compose.yml file.

Now let’s add some instructions to create our WordPress setup. In your code editor, paste the following in your docker-compose.yml file and save it.

version: '3'

services:
  db:
    image: mysql:5.7
    volumes:
      - db_data:/var/lib/mysql
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: somewordpress
      MYSQL_DATABASE: wordpress
      MYSQL_USER: wordpress
      MYSQL_PASSWORD: wordpress

  wordpress:
    depends_on:
      - db
    image: wordpress:5.1.1-php7.3-apache
    ports:
      - "8000:80"
    restart: always
    environment:
      WORDPRESS_DB_HOST: db:3306
      WORDPRESS_DB_USER: wordpress
      WORDPRESS_DB_PASSWORD: wordpress
    working_dir: /var/www/html
    volumes:
      - ./wp-content:/var/www/html/wp-content
      - ./uploads.ini:/usr/local/etc/php/conf.d/uploads.ini
volumes:
  db_data:

If you want to change the port that the WordPress install will use, just change the 8000 value in ports to whatever value you would like. If you want it to run on port 9210 you would make the change like so:

ports:
  - "9210:80"

Then instead of localhost:8000, the URL would be: localhost:9210

The first volumes parameter under wordpress is what tells Docker to surface the wp-content directory and the resulting WordPress directories in the local file system. (A special thanks to this Stack Overflow answer for helping me figure this part out.)

You don’t have to change anything here, it’s a local path that is keyed off the directory the config.yml file is in. The wp-content directory along with the themes and plugins directories will be created automatically when we run the Docker command to install everything. This is nice because anything created by WordPress (e.g. adding a plugin through the admin) or you (uploading an image) will show up in these directories just like they would on a server.

(See the 4/16/18 update at the end for information on the uploads.ini file and the 4/11/19 update for an explanation on the wordpress:image parameter.)

5 Run Docker Compose

Now we’re ready to run the Docker command that will build our local environment. In Terminal, make sure you are still in the directory we created in Section 3 (again you can check for the docker-compose.yml file by typing the ls command) and run the following command (when I say “run” I mean type and hit enter, just in case that’s not obvious):

docker-compose up -d

The command will begin running scripts and you should see various “Downloading” and “Waiting” messages appear in Terminal. This will take a little while to run.

6 Install WordPress

Once the script has finished running (you’ll know because the messages will stop scrolling on the screen and the terminal will be ready for you to type in it again) go to this URL in your browser (or if you changed the port number, go to whatever port you changed it to):

http://localhost:8000/

The standard WordPress installation screen should appear. Complete the installation like you normally would and then login to WordPress. As you can see you have a regular WordPress installation. Go to ‘Appearance > Themes’ and you’ll see the default WordPress themes. We’re almost finished.

7 Create the WordPress Theme

If you go back to the directory you created in Section 3 — this time open it in Finder — you’ll now see along with the docker-compose.yml file a wp-content directory and in there a themes directory and in there the default WordPress themes. This is just like having a normal WordPress install. Create a new folder and give it the name of your theme and then create an index.php and style.css file in the theme folder.

style.css

/*
Theme Name: My Theme
Author: David Yeiser
Author URI: http://davidyeiser.com/
Description: Sample theme for Docker setup.
Version: 0.1
*/

index.php

<!DOCTYPE html>
<html <?php language_attributes(); ?>>
<head>
  <meta charset="<?php bloginfo( 'charset' ); ?>">
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <?php wp_head(); ?>
</head>

<body <?php body_class(); ?>>

<div class="wrap">
  <div id="primary" class="content-area">
    <main id="main" class="site-main" role="main">

      <?php
      if (have_posts()) :
        /* Start the Loop */
        while (have_posts()) : the_post();
      ?>
        <div>
          <a href="<?php the_permalink(); ?>"><h3><?php the_title(); ?></h3></a>
        </div>
      <?php
        endwhile;
        /* End the Loop */
      else :
        // Nothing
      endif;
      ?>

    </main><!-- #main -->
  </div><!-- #primary -->
</div><!-- .wrap -->

<?php get_footer(); ?>
<?php wp_footer(); ?>

</body>
</html>

Save these files then refresh the themes page in your browser. You should now see your theme among the others. Activate your theme then go to http://localhost:8000/ and you should see the “Hello World!” post linked — that’s our theme!

From there you can develop the theme as you normally would. I’ve included three links at the end of this post for further reference if you’d like to learn more. And as mentioned in the beginning all the code from this tutorial is on GitHub: docker-wordpress-theme-setup.

Restarting

As long as Docker is running you’ll be able to access the WordPress install at http://localhost:8000/. If it’s ever not working restarting Docker usually fixes the problem. Just click the icon in the upper right and click the “Restart” button at the top of the dropdown menu.

More Resources

This tutorial was condensed from my setup experience and following other tutorials. Specifically these three:

If you have any trouble following this tutorial feel free to file an issue on GitHub.

Update 4/16/18

When you initiate a new Docker setup the default file upload limit is 2 MB, which is not ideal for a local development environment. To increase the upload limit you can add your own uploads.ini file (code below) in the same place as the docker-compose.yml file and then have latter point to the former. The code in Section 4 and in the GitHub repository has been updated to reflect this scenario.

file_uploads = On
memory_limit = 64M
upload_max_filesize = 64M
post_max_size = 64M
max_execution_time = 600

Update 4/11/19

Using the latest keyword for the WordPress Docker image installs an old version of WordPress and a fairly old version of PHP (5.6.3). This is usually fine — you can upgrade WordPress from the admin with ease. However, in my case the theme I was working on required PHP 7, which is not an easy upgrade. After more than a few Google searches and attempts at creating a separate PHP image and Nginx setup I realized all you have to do is be more specific with the tag that follows the WordPress image and Docker will install and link everything for you. In my case the tag specified was 5.1.1-php7.3-apache.

So then the updated property in the config.yml file changes from:

  wordpress:image: wordpress:latest
     …

to:

wordpress:image: wordpress:5.1.1-php7.3-apache
   …

I’ve updated the code in Section 4 above and in the GitHub repository to reflect this change as it installs a more modern version of PHP and the latest version of WordPress.