Add debian 11 bullseye official support

[AlistairB]

For the haskell docker images we want to support debian 11 bullseye. In terms of GHC, cabal and stack's debian 11 support the state of play is:

• GHC x86_64 - Support as of 9.4.1
• GHC aarch64 - Support coming in 9.4.3 9.6.1
• stack x86_64 - Appears to work for 2.7.5
• stack aarch64 - stack aarch64 is not being actively supported, so is excluded from the deb10 (and deb11) images which is fine.

Therefore, once GHC 9.4.3 9.6.1 (it has been postponed apparently) comes out we are good to add 9.6 line support for debian 11 excluding cabal.

cabal has support for x86_64-linux-deb10 and aarch64-linux-deb10, but does not include a release targeting debian 11. I have done some basic testing using cabal-install-3.8.1.0-x86_64-linux-deb10 in debian 11 and it appears to work. I have not tested cabal-install-3.8.1.0-aarch64-linux-deb10.

Can cabal add official support for debian 11?

[ulysses4ever]

For x64, it’s as simple as copying the deb-10 and bumping the DOCKER_REV, I tried it here: https://gitlab.haskell.org/ulysses4ever/cabal/-/pipelines/55722. I can submit it as a PR if the higher rank is willing to include it in principle.

Aarch64 is less clear: GHC has just reverted (see the ticket you referenced).

[Mikolaj]

Good idea about deb11.

[AlistairB]

Thanks, in terms of of the docker haskell images, we need both x64 + aarch64 to be able to release a deb11 version unfortunately. As you just release one image that should work for both.

Although just x64 is still a win I'm sure for other types of cabal users, so if you can release that easily you may as well.

[AlistairB]

Hmm GHC aarch64 deb11 support seems to be now milestoned for 9.6.1 . Oh well, no rush on this ;)

[tchoutri]

Any reason we can move on this, as Bullseye was released on September 20th?

[Mikolaj]

Is it included in https://gitlab.haskell.org/haskell/cabal/-/pipelines/58149? What else is needed?

[chreekat]

@AlistairB , aarch64 support for debian 11 was added in time for the 3.10.2 and 3.10.3 releases. E.g. https://downloads.haskell.org/cabal/cabal-install-3.10.3.0/cabal-install-3.10.3.0-aarch64-linux-deb11.tar.xz

To be transparent, I don't think this binary has been tested in CI at any point yet.