This multi-part series goes in depth in converting this site infrastructure to a containerized setup with Docker Compose. See the bottom of this post for other posts in the series.
As I mentioned in the last post, it was time to change hosting and I decided to go with DigitalOcean. But first, I had to figure out how to get all of my infrastructure deployed easily. DigitalOcean supports Docker, and I knew I could setup multiple containers easily using Docker Compose. I just had to decide on infrastructure.
Docker Compose allows one to script the setup of multiple containers, tying in all the necessary resources. There are thousands of prebuilt containers available on Docker Hub to choose from, or you can create your own. I knew I was going to have to customize most of my containers, so I chose to create my own, extending some existing containers. To begin with, I knew that I had three core requirements.
- Lucee - Open Source CFML Engine
- NGINX - Open Source Web Server/Application Platform
- MariaDB - Open Source Database Server
Now, I could've used a combined Lucee/NGINX container (Lucee has one of those built already), but I knew that I would use NGINX for other things in the future as well, so thought it best to separate the two.
When setting up my environment, I stepped in piece by piece. I'm going to layout each container in separate posts (as each had it's own hurdles), but here I'll give you some basics. You define your environment in a docker-compose.yml file. Spacing is extremely important in these files, so if you have an issue bringing up your environment spacing will be one of the first things you want to check. Here I'll show a simple configuration for a database server.
version: "3.3" services: database: container_name: mydb image: mariadb:latest env_file: - mariadb.env volumes: - type: bind source: ./sqlscripts target: /docker-entrypoint-initdb.d networks: my-network: aliases: - mysql - mydb restart: always
Here I've defined a network called my-network, and on that network I have a database service in a container called mydb. That container is aliased on the network as mydb and mysql. An alias is a name this container will be called when referenced by other containers. I bound a local folder (sqlscripts) to a folder in the container (docker-entrypoint-initdb.d). I also included a local file that contains the Environment Variables used by the container. This container used the actual mariadb image, but you could easily replace this line to point it to a directory with it's own Dockerfile defining your container (i.e. change 'image: mariadb:latest' to 'build: ./myimagefolder').
Bringing up your containers is simple. First you build your work, then you bring it up. From a terminal prompt:
> docker-compose up
You can add '-d' to that last command to skip all of the terminal output and drop you at a prompt, but sometimes it's good to see what's happening. To stop it all (when not doing '-d') just do Ctrl-C, otherwise just use 'docker-compose stop' or 'docker-compose down'. Going forward it will probably help to review the Docker Compose Command Line Reference
The Docker Compose File Reference is very extensive, providing a ton of options to work with. Here I'm using the 3.3 version of the file, and it's important to know which one you're using when you look at examples on the web, as options change or become deprecated from version to version.
That's a start to a basic Docker Compose setup. Continuing in the series we'll go over each container individually, and see how our Compose config ties it all together. Until next time...