FAQ

How do i test lower-bounds locally?

Using opam >= 2.2:

opam install --solver=builtin-0install "--criteria=+count[version-lag,solution]" .

in a fresh local switch at the root of the project you want to test.

A package (subtly) breaks in version < N and version N is being released, what should i do?

Create a new draft PR to restrict the previous version and merge it after version N is merged. e.g. #24243 (comment)

How to find lost archives of packages?

Archives of packages can be found from their checksum in alternative repository endpoints such as:

• https://gitlab.ocamlpro.com/OCamlPro/opam-repository/-/tree/cached
• https://opam.robur.coop
• https://opam.ocaml.org

Simply go to these url at the path: /cache/<name of checksum algorithm>/<first two characters of the hash>/<hash>. For example, dune.1.0.0's archive has the following checksum: md5=7435bc09a3967bf6da01e6cb7d37ccc3 so the archive is available at the following url:

• https://opam.ocaml.org/cache/md5/74/7435bc09a3967bf6da01e6cb7d37ccc3

If the original tarballs are available, we first ask the maintainers to replace their tarballs with the ones from the cache. When this is not possible or they are reluctant, we upload them to the opam-source-archives repository and update the opam files to point at the new location.

Note that if none of the known repositories have the archive you are looking for, the last resort could be archive.softwareheritage.org. However note that the checksum will not be the same as with the original archive and thus should not be trusted at face value.