Updates to opam-repo-ci which pull in the latest ocaml-version and ocaml-dockerfile releases trim the build matrix and add in the latest releases of Alpine and Ubuntu.
ocaml-version 4.1.0
ocaml-version 4.1.0 adds OCaml 5.6 as a dev version and 5.5.0~beta1 to unreleased_betas PR#88.
It also exposes a new significant list PR#87:
let significant =
let last_two = match List.rev all with
| a :: b :: _ -> [b; a] | _ -> [] in
List.sort_uniq compare ([ v4_08; v4_11; v4_14; v5_2 ] @ last_two)
Currently this resolves to [4.08; 4.11; 4.14; 5.2; 5.3; 5.4] which is a curated base from the 4.x series plus the last two releases as the list of OCaml versions against which opam packages should be regularly tested. For further detail, review the conversation on the thread of PR#88. This is a deliberate thinning of recent, which had grown to all stable releases from 4.08 to 5.4 (eleven versions).
In opam-ci-check, the all_supported list used to drive the full build matrix is updated to use significant:
let all_supported = Ocaml_version.Releases.significant @ Ocaml_version.Releases.unreleased_betas
The betas are only built on the master distro on x86_64, so this does not multiply out across the matrix.
Alpine 3.23 and Ubuntu 25.10 and 26.04
ocaml-dockerfile 8.3.5 adds Alpine 3.23, replacing Alpine 3.22 and add Ubuntu 25.10. Additionally, ocaml-dockerfile 8.3.6 adds Ubuntu 26.04. No code changes are required in opam-repo-ci; pulling in the updated dockerfile package and bumping the pinned opam-repository SHA in the Dockerfile and Dockerfile.web is sufficient.
Dropping i386 and Arm32
The extras function in lib/build.ml builds each non-master architecture against the two default compilers. Previously, this covered every arch in Ocaml_version.arches other than X86_64. PR#467 dropped Aarch32; this has been extended to also drop I386:
List.filter_map (function
| `X86_64 | `Aarch32 | `I386 -> None
| `Riscv64 -> ...
| arch -> ...
) Ocaml_version.arches
Neither architecture reflects a realistic target for modern opam packages, and both were a steady source of flaky builds that rarely surfaced genuine portability issues. See Issue#366 for more information. PR#346 proposes to stop build the 32-bit base images as well.