Main + PG_MAJOR not working in sources.list.d

[hyperknot]

I'm puzzled by this line.

postgres/11/Dockerfile

Line 85 in d21499f

echo "deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main $PG_MAJOR" > /etc/apt/sources.list.d/pgdg.list; \

According to postgresql IRC channel, 11 instead of Main has the purpose of installing client libraries for a specific version, for example libpq5.

However the way it is here, it'll add Main and 11, resulting in:

 apt-cache policy libpq5
libpq5:
  Installed: 12.2-1.pgdg16.04+1
  Candidate: 12.2-1.pgdg16.04+1
  Version table:
 *** 12.2-1.pgdg16.04+1 500
        500 http://apt.postgresql.org/pub/repos/apt xenial-pgdg/main amd64 Packages
        100 /var/lib/dpkg/status
     11.7-1.pgdg16.04+1 500
        500 http://apt.postgresql.org/pub/repos/apt xenial-pgdg/11 amd64 Packages

It of course means that the latest version from Main gets installed. Pretty much that makes the whole 11 part useless.

Not a big problem, as the Main version is supposed to be stable, but still, interesting regarding this line was changed from the Main only version some time ago.

[tianon]

Not a big problem, as the Main version is supposed to be stable, but still, interesting regarding this line was changed from the Main only version some time ago.

I dug into the commit history, and found we've had both since 2bfa44d (back in 2014).

For anything we install, we're explicit about the version, but this could pull in for dependencies. I suppose it's worth some testing to see what we'd lose by dropping main and going with the version-only APT repository instead.

[hyperknot]

The Postgres devs on IRC said that it's only affecting the client libraries, and those can be newer than server versions and are considered pretty stable. In that case maybe it should actually be the opposite, as in leaving only Main?

[yosifkit]

Found a reason for keeping both (and needing a pin priority): #678 (comment)

[hyperknot]

Do you mean that in that issue the libpq version has to be exactly the same as the server version?

[yosifkit]

Oh, that is not the problem. their Dockerfile builds fine when FROM postgres 10.12 (current release), but not 10.11 or 10.10.

It seems that /usr/lib/postgresql/10/lib/pgxs/src/makefiles/pgxs.mk is now part of postgresql-client-10 (10.12-1.pgdg90+1), but is not part of it in 10.11. I am not sure what older package provided it, but it doesn't matter since older packages are not available through the PostgreSQL apt repo. The solution is to use the newer image.

[tianon]

From https://apt.postgresql.org/pub/repos/apt/pool/README, we could technically drop $PG_MAJOR, but it's useful/important for beta or devel versions, and should not be causing harm otherwise. 👍

Edit: slightly more detail: according to https://wiki.postgresql.org/wiki/Apt, we only need main normally for all versions (realized this was the context for my comment 😅)