WIP: Maintenance on PostgreSQL clients

[sachilles]

Since PostgreSQL v18 was already published we need to provide a suitable postgresql client as well.

However, following the requirements for GitLab CE and in particular for PostgreSQL (see https://docs.gitlab.com/18.5/install/requirements/#postgresql) we should remove all clients for PostgresSQL versions smaller than 16.

[sachilles]

@kkimurak What do you think about this PR and the removal of old PostgreSQL client versions. I guess, we have to add a comment to the release notes. Otherwise it might be possible that a lot of users could run into trouble.

[kkimurak]

I think it's ok to remove old PostgreSQL clients. In addition to release notes, how about displaying a warning (or terminating with an error) if the minimum and maximum version requirements are not met?
The process for obtaining the server version has already been implemented, so changing it to the following should generally work (see my rough implementation: check-potgresql-server-version-and-warn branch based on this PR, especially commit 7199c08)

By the way, according to the link, Maximum PostgreSQL version for GitLab 18.x is 17.x (tested against GitLab 17.10 and later)

[sachilles]

@kkimurak Nice idea and I'll take over your commits. However, since GitLab does not support PostgreSQL v18 so far not officially, we'll wait before publishing this branch.

[sachilles]

@kkimurak Since GitLab version 19 (see #3250) requires at least PostgreSQL version 17, I would very much like to consider this PR.

Since I am not yet satisfied with the current state of the PR, I would modify it as follows:

• If the existing PostgreSQL server version is lower than the version required by GitLab, the container should not start, and a message indicating the necessary PostgreSQL update should appear.
• If the existing PostgreSQL server version is higher than the one required by GitLab, only a warning should be displayed; the container should not be prevented from starting.

What do you think?

[kkimurak]

@sachilles Thank you for your work and sorry for delay, generally looks good to me.
I found some mistake in my code. I don't think these will be a problem, but I'll correct them just in case.

[kkimurak]

Current postgresql 17.x release is 17.10 (170010) so my comment in code is stale a bit ((currently 17.6, is 170006)). If you find future maintenance troublesome, you might consider deleting the line.

$ docker run --rm -d --name psql17_test kkimurak/sameersbn-postgresql:17-20260521
b41212df4b1843b50091f6d452665847e3decc4f89dd2e9cff87af18077ab753

$ docker exec -it -u postgres psql17_test psql -h localhost -c 'SHOW server_version_num;'
 server_version_num 
--------------------
 170010
(1 row)

Suggested change

	# v18.5.2 : minimum = 16.5, maximum = 17.x (currently 17.6, is 170006)
	# v18.x : minimum = 16.5, maximum = 17.x (currently 17.10, is 170010)

[sachilles]

Took your comment and since rebased onto branch upgrade-to-19.0.0 adapted your suggestion for GitLab v19.x.

[sachilles]

@kkimurak Thanks for your additional review!

[kkimurak]

My home wired network connection is unavailable until the end of the month, and I only have a slow, data-limited connection, so I can't even fetch GitLab codebase and therefore can't build and test the image.
Anyway, from what I've quickly checked, it looks good to me.