[ANN] opam 2.1.0~rc2

The opam team has great pleasure in announcing opam 2.1.0~rc2!

The focus since beta4 has been preparing for a world with more than one released version of opam (i.e. 2.0.x and 2.1.x). The release candidate extends CLI versioning further and, under the hood, includes a big change to the opam root format which allows new versions of opam to indicate that the root may still be read by older versions of the opam libraries. A plugin compiled against the 2.0.9 opam libraries will therefore be able to read information about an opam 2.1 root (plugins and tools compiled against 2.0.8 are unable to load opam 2.1.0 roots).

Please do take this release candidate for a spin! It is available in the Docker images at ocaml/opam on Docker Hub as the opam-2.1 command (or you can sudo ln -f /usr/bin/opam-2.1 /usr/bin/opam in your Dockerfile to switch to it permanently). The release candidate can also be tested via our installation script (see the wiki for more information).

Thank you to anyone who noticed the unannounced first release candidate and tried it out. Between tagging and what would have been announcing it, we discovered an issue with upgrading local switches from earlier alpha/beta releases, and so fixed that for this second release candidate.

Assuming no showstoppers, we plan to release opam 2.1.0 next week. The improvements made in 2.1.0 will allow for a much faster release cycle, and we look forward to posting about the 2.2.0 plans soon!

Happy opam’ing! David, with Raja, Kate & Louis


I apologize for being persistent and noisy, but it really would be nice to documenting how to setup a mirror for opam repository itself, and the packages in question. How to setup local OPAM mirror

Maybe add a list of the officially recognized mirrors like some projects did.

If someone wants to contribute an opam manual PR, the steps for setting up an opam repository mirror are outlined in Mirroring support · Issue #4103 · ocaml/opam · GitHub.


For those on Ubuntu, I’ve refreshed the opam ppa to 2.1.0rc2:

add-apt-repository ppa:avsm/ppa
apt update
apt install opam