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New maintainers tutorial

Package your first recipe

Overview

Packaging a recipe is basically knowing a bag of about 20 tricks. Once you learn them, there is nothing more to learn. It can seem daunting at first but it's simple and easy to do once you know the tricks.

The nice thing about packaging is that only one person has to do it and then we all benefit. We've seen that over time, the core of the configuration doesn't really change. New options and versions might come but the config remains quite stable. This is good since it means that your packaging work stays relevant and useful for other maintainers & operators as time goes on.

Depending on your familiarity with recipes, it might be worth reading how a recipe is structured and making clear you understand what a recipe is before continuing.

Making a plan

The idea scenario is when the upstream project provides both the packaged image and a compose configuration which we can build from. If you're in luck, you'll typically find a Dockerfile and a docker-compose.yml file in the root of the upstream Git repository for the app.

  • Tired: Write your own image and compose file from scratch
  • Wired: Use someone else's image (& maybe compose file)
  • Inspired: Upstream image, someone else's compose file
  • On fire: Upstream image, upstream compose file

Writing the compose.yml

Let's take a practical example, Matomo web analytics. We'll be making a Docker "swarm-mode" compose.yml file.

Luckily, Matomo already has an example compose file in their repository. Like a lot of compose files, it's intended for use with docker-compose, instead of "swarm mode", but it should be a good start.

First, let's create a directory with the files we need:

abra recipe new matomo
cd ~/.abra/recipes/matomo

Then, let's download and edit the docker-compose.yml file:

mkdir matomo && cd matomo
wget https://raw.githubusercontent.com/matomo-org/docker/master/.examples/apache/docker-compose.yml -O compose.yml

Open the compose.yml in your favourite editor and have a gander 🦢. There are a few things we're looking for, but some immediate changes could be:

  1. Let's bump the version to 3.8, to make sure we can use all the latest swarm coolness
  2. We load environment variables separately via abra, so we'll strip out env_file
  3. The /var/www/html volume definition on L21 is a bit overzealous; it means a copy of Matomo will be stored separately per app instance, which is a waste of space in most cases. We'll narrow it down according to the documentation. The developers have been nice enough to suggest logs and config volumes instead, which is a decent start
  4. The MySQL passwords are sent as variables which is fine for basic use, but if we replace them with Docker secrets we can keep them out of our env files if we want to publish those more widely.
  5. The MariaDB service doesn't need to be exposed to the internet, so we can define an internal network for it to communicate with Matomo.
  6. Lastly, we want to use deploy.labels and remove the ports: definition, to tell Traefik to forward requests to Matomo based on hostname and generate an SSL certificate.

The resulting compose.yml is available here.

Test deployment

Running Co-op Cloud server required!

The rest of this guide assumes you have a Co-op Cloud server going -- we'll use swarm.example.com, but replace it with your own server address. Head over to the operators tutorial if you need help setting one up.

Now, we're ready to create a testing instance of Matomo:

abra app new matomo --secrets \
 --domain matomo.swarm.example.com \
 --server swarm.example.com

Depending on whether you defined any extra environment variables, we didn't so far, in this example, you might want to run abra app config swarm.example.com to check the configuration.

Otherwise, or once you've done that, go ahead and deploy the app:

abra app deploy swarm.example.com

Then, open the DOMAIN you configured (you might need to wait a while for Traefik to generate SSL certificates) to finish the set-up. Luckily, this container is (mostly) configurable via environment variables, if we want to auto-generate the configuration we can use a config and / or a custom entrypoint (see coop-cloud/mediawiki for examples of both).

Finishing up

You've probably got more questions, check out the maintainers handbook!