Reinstall glibc in playbook

[bedroge]

Fixes EESSI/gentoo-overlay#7.

I've added this as a separate step in install_packages.yml, as it requires noreplace: no, and I don't want to reinstall our entire set every time we (re)run this playbook. Also setting oneshot: yes to prevent glibc from being added to the world file.

We need another PR in https://github.com/EESSI/gentoo-overlay to remove glibc from the set.

[bedroge]

While making a PR in gentoo-overlay, I realized that we need to skip this step on macOS...

Done.

[bedroge]

Maybe it would also be nice if this step could check if it has already been run before.

[boegel]

@bedroge We should also add a check to make sure that the glibc installation we end up with actually picks up on /opt/eessi/lib?

[boegel]

@bedroge Tests fail with:

 /entrypoint.sh: line 12: /tmp/gentoo/usr/share/Lmod/init/profile: No such file or directory

[bedroge]

@bedroge We should also add a check to make sure that the glibc installation we end up with actually picks up on /opt/eessi/lib?

Yep, but I wanted to do that in some test script/suite that gets run by Ansible and/or a Github Action, see #42.

@bedroge Tests fail with:

 /entrypoint.sh: line 12: /tmp/gentoo/usr/share/Lmod/init/profile: No such file or directory

Hmm... I've seen that before on a local test: glibc fails to install, because of wrong settings in nsswitch.conf, which we pick up from the host (in this case: the docker container of the Github Action). So I guess we either need to patch the nsswitch.conf of this container, or run this step earlier (when the symlinks haven't been created yet).

[bedroge]

or run this step earlier (when the symlinks haven't been created yet).

Though that doesn't really work, since we also need to have our overlay added (which has the configuration files for the custom glibc installation)...

[bedroge]

Okay, I shuffled the steps a bit, so that this step get executed before the symlinks to the hosts are created. There's also a check now that does a grep for our defined dir on the libc library, so that this step only gets executed once.

I'm now passing the EXTRA_EMAKE="user-defined-trusted-dirs={{ prefix_user_defined_trusted_dir }} here in the playbook, since we need that location anyway to do the check. So we can probably remove the conf file added by the following PR:
EESSI/gentoo-overlay#8
Alternatively, we can keep that one and don't explicitly set EXTRA_EMAKE here, but then we still need to maintain the location of our directory /opt/eessi/lib in two places...

[peterstol]

checks passed :-( i was too fast

[bedroge]

@peterstol I was making some last/small improvements, but then the lint ci started complaining ;-)
It should be fine now.

[peterstol]

2nd attempt...