The old groupID changed when install a new package

[fushanqing]

Host system details
When I use the version of coreos 35.20220424.3.0, I use rpm ostree install rabbitmq-server. After successful installation and restart, the /usr/lib/group file is as follows：
rabbitmq:x:976:
When I execute rpm ostree memcached python3-memcached, its /usr/lib/group file is as follows:
memcached:x:976: rabbitmq:x:975:
rabbitmq's groupid changed from 976 to 975
How did this problem happen? How to solve it？Thank you！
Reproduction steps
Steps to reproduce the behavior:

1. rpm-ostree install rabbitmq-server
2. reboot
3. cat /usr/lib/group
4. rpm-ostree install memcached python3-memcached
5. reboot
6. cat /usr/lib/group

[fushanqing]

I found relevant problems in #1843
@lucab

[travier]

This one needs to be converted to a sysusers config too: https://src.fedoraproject.org/rpms/rabbitmq-server/blob/rawhide/f/rabbitmq-server.spec#_121

[travier]

I'd also recommend running that in a container if possible.

[fushanqing]

This one needs to be converted to a sysusers config too: https://src.fedoraproject.org/rpms/rabbitmq-server/blob/rawhide/f/rabbitmq-server.spec#_121

When I use the latest version of coreos 36.20220505.3.2, this problem does not appear. How is this problem solved?

[lucab]

The ID allocation depends on the ordering of %pre runs, so it may be observed non-deterministically in some cases.

A workaround could be to pre-create system users before layering the packages, for example via Ignition and systemd-sysusers:

$ cat /etc/sysusers.d/local_ids.conf
#Type  Name       ID  GECOS                        Home directory     Shell
u      rabbitmq   -   "RabbitMQ messaging server"  /var/lib/rabbitmq  /sbin/nologin
u      memcached  -   "Memcached daemon"           /run/memcached     /sbin/nologin

This is indeed a duplicate of #1843, let's keep that one and close this instead.