Two SSL-Enabled WordPress Sites on one EC2 Instance with Docker (pt.1)

By WedBot

When I created this site, I wanted to make sure that I could run a segregated technical blog away from the human site, as well as enable HTTPS for security. This 2 part article will walk you through how to run 2 SSL-Enabled WordPress installations on a single server with Docker, using LetEncrypt for certification, and Nginx as a reverse proxy.

A Reverse Proxy?!

I decided that the technical blog should be WordPress, and whilst I decided how the main site would be implemented, I should also put a WordPress installation in place there too. The challenge was running 2 websites listening on port 80 on the same server, with 2 different subdomains. This is where Nginx comes into play – a reverse proxy will take incoming requests, and route them to the correct destination. This is even easier when combined with Docker.

Docker Configuration

I’m using a docker-compose file to takes care of dependencies and allow data to be stored back to the EC2 instance using volumes. It’s important to remember that Docker containers are ephemeral, so no data should be stored in the container itself. Eventually persisted data should be moved onto EBS so that it will exist even when the underlying EC2 instance is destroyed.

You’ll see below that I’m using version 3.3 of the docker-compose.yml format. As I’m relatively new at all this, I’m not too bothered about backwards compatibility of my files. You can see a few important things:

  • Volumes are mapped for db1 and site1, allowing them to write data onto the host of the containers – in this case the EC2 instance.
  • depends_on for site1 is set to db1, ensuring startup dependency
  • working_dir is set for container site1. This is probably the most important setting, to get WordPress to write to a specific directory.
version: '3.3'
services:
  db1:
    image: mysql:5.7
    restart: always
    volumes:
      - ./site1_db:/var/lib/mysql
    environment:
      MYSQL_ROOT_PASSWORD: rootpassword
      MYSQL_DATABASE: wordpress
      MYSQL_USER: userword
      MYSQL_PASSWORD: password
  site1:
    image: wordpress:5-fpm
    depends_on:
      - db1
    restart: always
    working_dir: /var/www/html/site1
    volumes:
      - ./site1_wp:/var/www/html/site1
    environment:
      WORDPRESS_DB_HOST: db1:3306
      WORDPRESS_DB_USER: username
      WORDPRESS_DB_PASSWORD: password

The config above will set up one database and WordPress instance, and so you will need to copy db1 and site1 to create a second one. Don’t forget to change your working directory and volume to a different location for your second instances. You will end up with a docker-compose file that looks like below.

services:
  db1:
    # skipped for clarity
  site1:
    # skipped for clarity
  db2:
    # skipped for clarity
  site2:
    # skipped for clarity
  website:
    image: nginx
    depends_on:
      - db1
      - site1
      - db2
      - site2
    restart: always
    volumes:
      - ./nginx.conf:/etc/nginx/conf.d/default.conf
      - ./logs:/var/log/nginx
      - ./site1_wp:/var/www/html/site1
      - ./site2_wp:/var/www/html/site2

You can see that I’ve also added the Nginx container config called website, and there are several important volumes configured.

  • There is also a logs directory so that you will be able to access logs from EC2 rather than having to remote into the container.
  • I have specified the directories of both WordPress containers, so that Nginx can serve up the content from the host.
  • A nginx.conf file location which will be passed to the Nginx service in the container.

In Part 2 of this article I will show you how to configure your Nginx config file to pick up and serve both WordPress sites, and how to enable HTTPS.

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