Support specifying system packages to install in Docker

[palmskog]

Some extraction projects rely on OCaml libraries that require certain system packages to be installed. There should be a way in meta.yml to specify these system packages and have them be installed in Travis and other CIs that rely on Docker images.

[Zimmi48]

The good practice in this case is to use opam depext fields. Then, the CI templates could simply run opam-depext (which is included in opam >= 1.1).

[erikmd]

@Zimmi48 for this feature request, should we create a related issue in https://github.com/coq-community/docker-coq-action/issues as well?

[Zimmi48]

@erikmd I guess so.

[erikmd]

Hi @palmskog,

do you believe this use case still needs some automation via a dedicated feature in docker-coq-action and/or in templates?

FWIW, there is now:

• some documentation in docker-coq-action's README: Install Debian packages;
• and a "demo" GHA job in docker-coq-action's CI that checks on a docker-coq image, an install script example using apt-get.

But as mentioned earlier by @Zimmi48 − #41 (comment) −, some (not all) system-wide install can be triggered by opam-depext…

[palmskog]

@erikmd I still need this feature for some of my projects, but the non-depext workaround (your installation of Debian packages) is not a huge pain. But hasn't depext now been improved in opam 2.1 and later? I think we can keep this issue open until we figure out the "right" way to install depext'd stuff.

[Zimmi48]

Yes, opam-depext is now superseded by opam install itself in opam 2.1.