We try to provide sensible defaults in the discourse_docker images but it’s not possible to account for every possible use case. Feel free to customise your images to hold versions back if you prefer.
To a certain extent the dependency versions reflect our hosting requirements - we use the base image internally. That means it shouldn’t get too stale, but also means there are only so many permutations we can maintain.
That’s a perfectly valid method if you’re more comfortable with it.
If the warning is generated while preparing to dump the old DB then this is nothing to worry about. We are only running the server against the old data directory for the purpose of running pg_dump. When the dump is restored into the new server indexes are recreated.
The reason you’re seeing this is that in the last few days we have released a new version of the base image which upgrades from Debian Bookworm to Trixie, changing the glibc version. Locales based on the libc provider (which you were probably using) are not stable across glibc upgrades, so when the upgrade script starts a Postgres server to dump your old data it displays collation mismatch warnings.
The collation mismatch is the whole reason we are doing the dump-and-restore instead of running pg_upgrade. Once your DB is using C.UTF-8 with the builtin provider upgrades to glibc will no longer affect collations.