If you’ve ever thought about setting up a multisite WordPress installation via Docker I highly recommend you do so as it is an excellent project to revisit several topics.

Overview:

1. Load new Oracle 7.7 system via PXE and join to domain
2. Install Docker & Docker Compose
3. Acquire Docker Compose script from online video (Reference: https://www.youtube.com/watch?v=pYhLEV-sRpY)
4. Modify script to work in an SELinux enabled environment
5. Modify script to work with multisite
6. Modify script to allow a larger upload size
7. Run Docker Compose
8. Configure WordPress for multisite
9. Setup DNS entries & modify sites to use full domain names

What is great about this Docker setup is by stopping and then restarting the Docker Compose, WordPress will automatically be updated if a new release has come out.  With a High Availability setup, you can restart one WordPress instance at a time, allowing for no downtime during upgrades.

# create directory to store docker compose configuration & change to it
mkdir -p docker/wordpress
cd docker/wordpress

# create uploads.ini file which is used to configure a larger upload size
cat > uploads.ini
upload_max_filesize = 64M
post_max_size = 64M
memory_limit = 400M
file_uploads = On
max_execution_time = 180

# create docker-compose.yaml file
# original version: https://www.youtube.com/watch?v=pYhLEV-sRpY
cat > docker-compose.yaml
version: '3'
 services:
   # Database
   db:
     image: mysql:5.7
     volumes:
       - db_data:/var/lib/mysql
     restart: always
     environment:
       MYSQL_ROOT_PASSWORD: password
       MYSQL_DATABASE: wordpress
       MYSQL_USER: wordpress
       MYSQL_PASSWORD: password
     networks:
       - wpsite
   # WordPress
   wordpress:
     depends_on:
       - db
     image: wordpress:latest
     ports:
       - '80:80'
     restart: always
     privileged: true
     volumes:
       - ./html:/var/www/html
       - ./uploads.ini:/usr/local/etc/php/conf.d/uploads.ini
     environment:
       WORDPRESS_DB_HOST: db:3306
       WORDPRESS_DB_USER: wordpress
       WORDPRESS_DB_PASSWORD: password
     networks:
       - wpsite
 networks:
   wpsite:
 volumes:
   db_data:

Notes on docker-compose.yaml:
1. MySQL is loaded via Container image. Data is stored in local volume.
2. MySQL & WordPress are able to interact via a local network wpsite.
3. With a Multisite configuration port 80 is required.
4. “Privileged” must be used as we are using an enforced SELinux environment.

# create directory to store wordpress files
mkdir html

# Start up WordPress via docker-compose
docker-compose up -d

# Configure firewall
firewall-cmd --permanent --add-port 80
firewall-cmd --reload

Next a configuration file must be modified:
./html/wp-config-sample.php

Locate the string “That’s all, stop editing! …” and add the following lines after:

define(‘WP_ALLOW_MULTISITE’, ‘true’);
define(‘COOKIE_DOMAIN’, $_SERVER[‘HTTP_HOST’]);

After logging into the WordPress site for the first time browse to:
Tools -> Network, choose subdomains or subfolders and follow directions.

Finally, you can use a domain instead of a subdomain or subfolder by first creating a site with a subdomain or subfolder then, after configuring the domain in DNS, go back to the site and modifying the URL with the domain. For example: wp-1.com/travisloyd –> www.travisloyd.xyz