Hello,
We've just been bit by some libvirt updates in our project (Apache
Cloudstack) which basically broke basic functionality on AlmaLinux 8.4.
I expected the same problem to happen on RockyLinux 8.4, however turns
out the libvirt on this one was an older version and not even "yum
update" changed this.
On closer investigation I noticed Rocky actually ships 5 "virt" modules,
according to "yum module info virt", my Alma test box only ships one,
which is also very up to date.
No actual complaints here, but can someone explain to me why the
discrepancy? Didn't use EL8 much, but expected all "clones" to be more
or less identical, but turns out there are differences that matter.
Hmm I do not know what is going on with the Rocky side of things, but I am guessing there might have been a mismatch on how to build module 'versions' as module 'streams'. Let us look at perl and virt as examples. RHEL offers 4 perl streams with different lifetimes and support leveles (
https://access.redhat.com/support/policy/updates/rhel-app-streams-life-cycle ) and only one virt stream.
```
[root@vector-8 ~]# dnf module list perl
Updating Subscription Management repositories.
Last metadata expiration check: 1:11:06 ago on Fri 13 May 2022 06:44:03 EDT.
Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)
Name Stream Profiles Summary
perl 5.24 common [d], minimal Practical Extraction and Report Language
perl 5.26 [d][e] common [d], minimal Practical Extraction and Report Language
perl 5.30 common [d], minimal Practical Extraction and Report Language
perl 5.32 common [d], minimal Practical Extraction and Report Language
Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
[root@vector-8 ~]# dnf module list virt
Updating Subscription Management repositories.
Last metadata expiration check: 1:11:20 ago on Fri 13 May 2022 06:44:03 EDT.
Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)
Name Stream Profiles Summary
virt rhel [d][e] common [d] Virtualization module
Hint: [d]efault, [e]nabled, [x]disabled, [i]nstalled
```
The virt module has had multiple versions over its lifetime with RHEL-8. The EPEL build system accidently keeps a list of them due to grobisplitter putting them into trees when they are first seen.
```
2019-09-19 virt:rhel:8000020190618154454:f8e95b4e:x86_64/
2019-11-07 virt:rhel:8000020190828150510:f8e95b4e:x86_64/
2019-12-18 virt:rhel:8010020190916153839:cdc1202b:x86_64/
2020-01-30 virt:rhel:8010020191202185848:c27ad7f8:x86_64/
2020-04-08 virt:rhel:8010020191216093608:c27ad7f8:x86_64/
2020-04-29 virt:rhel:8010020200304114113:c27ad7f8:x86_64/
2020-07-01 virt:rhel:8020020200316135718:6a468ee4:x86_64/
2020-09-30 virt:rhel:8020020200601195459:4cda2c84:x86_64/
2020-11-03 virt:rhel:8020020200909224913:4cda2c84:x86_64/
2020-12-16 virt:rhel:8030020200909014558:30b713e6:x86_64/
2021-02-17 virt:rhel:8030020201123162111:229f0a1c:x86_64/
2021-03-04 virt:rhel:8030020210205201602:229f0a1c:x86_64/
2021-05-21 virt:rhel:8030020210210212009:229f0a1c:x86_64/
2021-08-11 virt:rhel:8040020210317013608:9f9e2e7e:x86_64/
2021-11-10 virt:rhel:8040020210721215855:522a0ee4:x86_64/
2021-12-22 virt:rhel:8050020211001230723:b4937e53:x86_64/
2022-02-02 virt:rhel:8050020211203195115:c5368500:x86_64/
2022-03-16 virt:rhel:8050020220113125354:c5368500:x86_64/
2022-04-27 virt:rhel:8050020220208234339:c5368500:x86_64/
2022-05-11 virt:rhel:8050020220322234807:c5368500:x86_64/
2022-05-11 virt:rhel:8060020220408104655:d63f516d:x86_64/
```
To a user you should see only one module stream which is virt:rhel. It should then continuously get updated when the 'version' of the module is updated and all the packages in this 'pseudo-repository' are updated en-mass. I do not know how Rocky has split things up and it could be for multiple reasons like they are offering alternative streams or their tooling at one point split things in different ways than RHEL does.