Building an Elixir Release into a Docker image using GitLab CI - Part 1

This post details the process of building an Elixir release into a Docker image using GitLab CI. It outlines the CI pipeline configuration with stages for build, styles, test, release, and cleanup, including variable passing and the use of custom Dockerfiles (`Dockerfile.build` and `Dockerfile`). It also describes the manual linking of services like PostgreSQL and Kafka in test stages and the use of `docker build` and `docker push` for creating and uploading release images to the GitLab Container Registry. Existing problems and future plans for Erlang hot upgrades, automated release testing, and native Erlang messaging are also mentioned.