Pin PostgreSQL version

[danielhollas]

I've just hit an issue in one of my full-stack based container, which cannot start since it was created with PSQL=14, but somewhere along the way we updated to PSQL==15.

I've looked around and we don't seem to be in control of the PSQL version in our docker stacks. PSQL is installed as part of the aiida-core.services conda package. However, looking the the conda recipe on conda-forge, the psql version is not pinned, only a lower bound is given. @sphuber do I understand the situation correctly?

https://github.com/conda-forge/aiida-core-feedstock/blob/9bf266a74d8af2b0d866bb4d99f853fa3785c5c1/recipe/meta.yaml#L103

If that is the case, a major PSQL update can happen essentially any time we rebuild and publish the docker stack images here, which seems suboptimal, to put it mildly. Even when the automatic postgres migration is finished in #25, I'd say it is still highly desirable to be in control of the Postgres version, so that we do not inflict migrations on users randomly.

@unkcpz @yakutovicha if you agree, I'll cook up a PR with the change.

[unkcpz]

Thanks @danielhollas, I fully agree that we need to pin the PostgreSQL version for the image explicitly. Please go ahead with the PR.

[yakutovicha]

I agree, with the proposition, thanks @danielhollas. The only question is whether to fix it here (in the docker stack) or in conda forge.

Probably, fixing the PGSQL version in the aiida-core services is not ideal, as it should represent the services with which aiida-core is compatible.

[danielhollas]

Yeah, I've thought about it as well, and I also don't think fixing it in Conda is a good idea, since it would tie specific version of AiiDA to a specific version of PSQL, whereas normally you'd want to be able to upgrade AiiDA without upgrading PSQL.

[danielhollas]

Thanks @yakutovicha. Btw as you can see, the project automation works and the issue has been automatically marked as Done when being closed by merging the PR. CC @unkcpz