ocaml-layer

Bring your team's OCaml CI jobs down to 1 min.

Motivation

The goal is to set up a cached build environment on which your team can compile and test their own OCaml software, quickly every time.

• Pre-install all the external dependencies - opam packages and more.
• Start from the base Docker image of your choice.
• It's admin-friendly. Maintenance requires no OCaml knowledge.
• Customize by forking and editing this git repo.
• It's Docker. Reproducible locally and not tied to a CI vendor's caching.

Usage

For evaluation purposes, you can simply run make and watch an image being built with some default settings.

For actual use, follow these steps:

1. Create your own Docker repository on Docker Hub or some other registry.
2. Fork this git repository.
3. Add packages to the lists in common-config.sh.
4. Create or edit one configuration file per container, in configs/.
5. Adjust the SELECTED_CONFIGS variable in the Makefile.
6. Run make to build the Docker images.
7. Run make push to upload the images.
8. Use these images as base images in your CI jobs.

You can reuse and adapt the CircleCI config of this repo to rebuild your images on a weekly basis or so.

Example

The config I use for my own needs is common-config.sh and configs. The Docker images end up on Docker Hub: minimum OCaml version and latest OCaml. They are updated weekly using CircleCI (config).

Suggestions

• If you're an individual open-source developer, you may want to target two versions of OCaml: the minimum version that you're willing to support and the latest version.
• The ocaml/opam2 images already support many flavors of operating systems and are graciously maintained for you. You probably should use those if the speed of routine CI builds isn't a priority for you.