OCaml Docs CI (aka ocaml-docs-ci or just docs-ci) is an OCurrent pipeline used to build the documentation for ocaml.org website. It uses the metadata from opam-repository to work out how to build documentation for individual packages using voodoo, the OCaml package documentation generator, and generates a HTML output suitable for ocaml.org server.

Installation

Get the code with:

git clone --recursive https://github.com/ocurrent/ocaml-docs-ci.git
cd ocaml-docs-ci

Then you need an opam 2.1 switch using OCaml 4.14. Recommend using this command to setup a local switch just for docs-ci.

# Create a local switch with packages and test dependencies installed
opam switch create . 4.14.1 --deps-only --with-test -y
# Run the build
dune build
# Run the tests
dune build @runtest

Architecture

At a high level docs-ci purpose is to compile the documentation of every package in the opamverse. To do this it generates a dependency universe. For each package (along with the version), the documentation is generated for it plus all of its dependencies. This documentation is then collected into a documentation set and provided to the ocaml.org service. The voodoo tool defines the on disk format for the documentation set.

For further details on how docs-ci works read the pipeline diagram.

Deployment

ocaml-docs-ci is deployed as into two environments, with ocurrent-deployer. The application is deployed as a series of Docker containers from a git branch.

Environments:

OAuth integration provided by GitHub OAuth Apps hosted under the OCurrent organisation. See https://github.com/organizations/ocurrent/settings/applications

The infrastructure for docs-ci is managed via Ansible, contact @tmcgilchrist or @mtelvers if you need access or have questions.

To deploy a new version of docs-ci:

1. Create a PR and wait for the GH Checks to run (ocaml-ci compiles the code and ocurrent-deployer checks it can build the Dockerfiles for the project)
2. Test the changes on staging environment by git cherry picking the commits to that branch and pushing it
3. Check deploy.ci.ocaml.org for docs-ci

Follow a similar process for live exercising extra caution as it could impact the live ocaml.org service.

The git history on live and staging MUST be kept in sync with the default branch. Those branches should be the same as main plus or minus some commits from a PR.

Remote API

docs-ci has a cli tool (ocaml-docs-ci-client) for interacting with the pipeline over CapnP. It provides commands to:

• diff-pipelines - to show the changes between two pipeline runs
• health-check - to provide information about a specific pipeline run
• status - build status of a package
• status-by-pipeline - build status of a package in the two most recent pipeline runs
• steps - build steps of a package

The output is via json, which is intended to be combined with jq to display and query for pieces of information.

Local Development

ocaml-docs-ci is runable as:

dune exec -- ocaml-docs-ci \
    --ocluster-submission cap/XXX.cap \
    --ssh-host ci.mirage.io \
    --ssh-user docs \
    --ssh-privkey cap/id_rsa \
    --ssh-pubkey cap/id_rsa.pub \
    --ssh-folder /data/ocaml-docs-ci \
    --ssh-endpoint https://ci.mirage.io/staging \
    --jobs 6 \
    --filter mirage \
    --limit 6

A docker-compose.yml is provided to setup an entire docs-ci environment including:

• ocluster scheduler
• ocluster Linux x86 worker
• nginx webserver for generated docs
• ocaml-docs-ci built from the local git checkout

Run this command to create an environment:

$ docker-compose -f docker-compose.yml up

You should then be able to watch the pipeline in action at http://localhost:8080.

Overriding the odoc toolchain

By default a profile documents the world with the mainline odoc / odoc-driver / sherlodoc from opam-repository. To instead build the docs with an odoc toolchain from a git branch (e.g. to test an unreleased odoc fix across the whole opamverse), use a github pin overlay.

Pass one or more overlays on the command line (see the daemon service in docker-compose.yml):

--github-pin-overlay=https://github.com/jonludlam/odoc#eliom-fix=overlays/eliom-fix

The argument is URL[#BRANCH]=PATH:

• URL — the odoc fork to track (omit #BRANCH to track the default branch).
• PATH — where, under .day11/, to materialise the overlay.

On a schedule the daemon then:

1. clones/fetches the branch into ‹PATH›/upstream;
2. reads the branch HEAD sha, the latest git tag (e.g. 3.2.1), and the commit's committer epoch (git show -s --format=%ct);
3. regenerates a small opam-repository at ‹PATH›/repo containing odoc, odoc-driver, odoc-parser, odoc-md and sherlodoc, each at a synthesised version ‹tag›+‹branch›.‹epoch›.‹sha7› (e.g. 3.2.1+eliom-fix.1782817535.116707b) whose url.src points at the exact branch commit.

Because the +‹branch›.… suffix sorts higher than the plain mainline version, and the epoch is monotonic, the solver always prefers the newest commit on the branch — so each push to the branch is automatically picked up, rebuilds the doc toolchain, and re-links the world against it.

A profile opts in by listing the overlay in its opam_repositories, after mainline, in its ‹profile›.json:

"opam_repositories": ["repo/opam-repository", "overlays/eliom-fix/repo"]

The overlay is visible both to the doc-toolchain resolver (so odoc/ odoc-driver are built from the branch) and to every package's with-doc closure. The bundled eliom-fix profile is a worked example; its eliom-baseline twin is identical but without the overlay, so diffing the two isolates exactly what the odoc changes did to the output.

Migrations

Migrations are managed using omigrate. If you are using an opam switch for ocaml-docs-ci then omigrate should be installed and you can create a new migration by doing this from the project root:

$ omigrate create --dir migrations <migration-name>

This will create timestamped files in the migrations directory that you can then populate with the sql necessary to introduce and remove the migration (in the up and down files respectively).

Migrations will not run unless the --migration-path flag is present when invoking ocaml-docs-ci-service.

Epoch management

Epochs are used in ocaml-docs-ci to organise sets of artifacts all produced by the same odoc/voodoo version. There is a cli tool for managing epochs described in epoch.md.