The OCaml Infrastructure: Tools and Services for the OCaml Ecosystem

The OCaml ecosystem is supported by a robust infrastructure built around OCurrent. The OCaml Infrastructure powers many essential services that OCaml developers rely on daily.

What is OCurrent?

OCurrent is an OCaml eDSL for creating processing pipelines that automatically adjust when their inputs change. For example, when a Git repository is updated, OCurrent pipelines can automatically rebuild, test, and deploy the changes without manual intervention.

OCaml Infrastructure Services

The OCaml infrastructure services can be grouped into three main categories: Community infrastructure services, services for individual projects, and infrastructure operation services. Here we present a brief overview of the major services from the first two categories.

Docker Base Images

Source Code: docker-base-images

Website: images.ci.ocaml.org

This service builds the official ocaml/opam Docker images for various Linux distributions, OCaml versions, compiler flags, and architectures (including x86, ARM, PowerPC, s390x, and RISC-V). These images provide a consistent environment for development and testing and are used by many other CI services.

Using the pre-built OCaml Docker images: You can view the available pre-built Docker images for various OCaml configurations at DockerHub, and use them in your own deployments.

Package Submission CI (opam-repo-ci)

Source Code: opam-repo-ci

Website: opam.ci.ocaml.org

Tests package submissions to the opam repository. When you submit a pull request to opam-repository, this service verifies that your package builds correctly and also tests all dependent packages to ensure compatibility.

Maintaining compatibility for packages in the opam-repository: After publishing a package by creating a GitHub release and opening an opam-repository PR (e.g. by using dune-release), monitor your opam-repository PR to ensure all tests pass.

Documentation CI

Source Code: ocaml-docs-ci

Website: docs.ci.ocaml.org

Builds documentation for all packages in the opam repository, with correct cross-package linking. After publishing your package to opam-repository, the documentation will automatically be built and published to the OCaml.org website's package area.

Health Check Services

• check.ci.ocaml.org: Regularly tests that all packages in the opam repository still build correctly. This service is used by OCaml compiler developers when preparing major changes like new OCaml compiler releases. GitHub: opam-health-check
• dune.check.ci.dev: Regularly tests OCaml packages with the Dune build system to ensure compatibility and correctness.
• windows.check.ci.dev: Tests OCaml packages on Windows platforms to identify Windows-specific issues in the OCaml ecosystem and to assist package maintainers in supporting Windows environments.
• freebsd.check.ci.dev: This service helps package maintainers identify and fix FreeBSD-specific issues in their packages, by testing OCaml packages on FreeBSD to ensure compatibility.
• oxcaml.check.ci.dev: Tests OCaml packages with OxCaml, an alternative OCaml compiler implementation. This service helps identify compatibility issues between packages and the OxCaml compiler variant.

Platform Support

The OCaml infrastructure supports building and testing on multiple platforms:

• Linux: Various distributions (Debian, Ubuntu, Alpine, etc.)
• Architecture diversity: x86_64, ARM64, ARM32, PowerPC, s390x, RISC-V
• macOS: Through macos-infra
• FreeBSD: Through freebsd-infra

Getting Involved

The OCaml infrastructure is open source and welcomes contributions. You can:

• Contribute to the various codebases on GitHub
• Report issues or suggest improvements on the OCaml infrastructure repository on GitHub, or on discuss.ocaml.org
• Deploy the tools locally to test your projects (see the individual documentation of the service you want to run)

For more information on OCurrent and these services, visit ocurrent.org or explore the OCurrent GitHub organization.