Detect CentOS properly instead of defaulting to epel

[jakub-vavra-cz]

= changelog =
msg: Fix detection of CentOS Stream
type: bugfix
resolves: #524

[praiskup]

Thank you for the PR!

The authors wanted to use epel-X on the Enterprise Linux family of distributions, and I believe this is what users are used to having - this might well be a breaking change (at least the part of PR affecting RHEL).

For the other cases, the dnf copr enable PROJECT centos-stream-9-x86_64 command variant lets you select the chroot. There's no logic for fallbacks (like try epel, then rhel, then centos-stream, amazonlinux, ...). Something along those lines was done in dnf5 copr enable.

[praiskup]

Just for the record, dnf4 copr enable downloads repofiles from copr frontend, something like:
https://copr.fedorainfracloud.org/coprs/@mock/mock/repo/fedora-39/dnf.repo?arch=x86_64
With this approach, dnf copr has to a decision in advance, before the request is done.

The dnf5 copr enable though works with (a relatively new) Copr API that provides better "project introspection":
curl https://copr.fedorainfracloud.org/api_3/rpmrepo/@mock/mock/rhel-8/ | jq
dnf5 copr then builds the repo file contents on the client side.
Using the same API in dnf4 copr would be interesting, though the question is whether we want to do such a rewrite.

[praiskup]

Thank you for the update.

This is not something I'd love to make decisions on. I'd suggest you: ask the CentOS Stream community.

Just note that the CentOS Stream build chroots have a lower chance to even exist in the project:

And then, from my observation only, it is a relatively known fact that epel-* is the default decision DNF copr plugin on the Enterprise Linux-based distros, so if anyone has to provide some "stable and supported content" in Copr for EL, they provide epel- chroots. The centos-stream-* or centos-stream+epel-* chroots in Fedora Copr are typically used just for CI testing.

[jakub-vavra-cz]

Hello @praiskup ,
I have dropped the RHEL part of change as it might be breaking.
I still think that each distro should default to its appropriate chroot/repo and only if You want something else You should select chroot explicitly, but this is not the hill I die on.

We are running the same automation on fedora, centos and rhel so we want to just run "dnf copr enable PROJECT" and we expect that it will work properly pulling the right one.

I wanted to avoid writing my own _guess_chroot in ci automation.

According to Your plot there is a significant number of centos-stream-9-x86_64 and centos-stream-8-x86_64.

[praiskup]

Just two more interesting queries, number of EL-based chroots (or "projects") currently in Fedora Copr (excluding the temporary projects):

coprdb=# select mock_chroot.id, mock_chroot.os_release, mock_chroot.os_version, count(*) as c from copr_chroot join mock_chroot on mock_chroot.id = copr_chroot.mock_chroot_id join copr on copr.id = copr_chroot.copr_id where mock_chroot_id in (select id from mock_chroot where os_version in ('8', '9') and copr.delete_after is null and is_active = true and os_release != 'mageia' order by os_release) group by mock_chroot.id order by c desc;
┌─────┬─────────────────────────┬────────────┬──────┐
│ id  │       os_release        │ os_version │  c   │
├─────┼─────────────────────────┼────────────┼──────┤
│  82 │ epel                    │ 8          │ 5732 │
│ 143 │ epel                    │ 9          │ 2999 │
│  85 │ centos-stream           │ 8          │ 2276 │
│ 130 │ centos-stream           │ 9          │ 1895 │
│  84 │ epel                    │ 8          │ 1871 │
│ 144 │ epel                    │ 9          │ 1354 │
│  86 │ centos-stream           │ 8          │ 1070 │
│ 131 │ centos-stream           │ 9          │ 1002 │
│  83 │ epel                    │ 8          │  943 │
│ 148 │ epel                    │ 9          │  717 │
│ 146 │ epel                    │ 9          │  637 │
│ 171 │ rhel                    │ 9          │  636 │
│ 145 │ epel                    │ 8          │  489 │
│  87 │ centos-stream           │ 8          │  464 │
│ 170 │ rhel                    │ 8          │  427 │
│ 168 │ centos-stream+epel-next │ 9          │  426 │
│ 147 │ centos-stream           │ 9          │  412 │
│ 155 │ centos-stream           │ 9          │  345 │
│ 178 │ rhel                    │ 9          │  295 │
│ 165 │ centos-stream+epel-next │ 9          │  276 │
│ 162 │ centos-stream+epel-next │ 8          │  258 │
│ 163 │ centos-stream+epel-next │ 8          │  173 │
│ 166 │ centos-stream+epel-next │ 9          │  170 │
│ 167 │ centos-stream+epel-next │ 9          │  164 │
│ 164 │ centos-stream+epel-next │ 8          │  126 │
│ 189 │ rhel                    │ 8          │  118 │
│ 188 │ rhel                    │ 9          │   97 │
│ 187 │ rhel                    │ 8          │   68 │
└─────┴─────────────────────────┴────────────┴──────┘

More epel-enabled chroots.

Here including the temporary projects:

coprdb=# select mock_chroot.id, mock_chroot.os_release, mock_chroot.os_version, count(*) as c from copr_chroot join mock_chroot on mock_chroot.id = copr_chroot.mock_chroot_id join copr on copr.id = copr_chroot.copr_id where mock_chroot_id in (select id from mock_chroot where os_version in ('8', '9') and is_active = true and os_release != 'mageia' order by os_release) group by mock_chroot.id order by c desc;
┌─────┬─────────────────────────┬────────────┬───────┐
│ id  │       os_release        │ os_version │   c   │
├─────┼─────────────────────────┼────────────┼───────┤
│  85 │ centos-stream           │ 8          │ 17167 │
│  82 │ epel                    │ 8          │ 16118 │
│ 130 │ centos-stream           │ 9          │ 15736 │
│ 143 │ epel                    │ 9          │  8688 │
│ 131 │ centos-stream           │ 9          │  5825 │
│  84 │ epel                    │ 8          │  4869 │
│ 170 │ rhel                    │ 8          │  4318 │
│  86 │ centos-stream           │ 8          │  4178 │
│ 171 │ rhel                    │ 9          │  3486 │
│ 168 │ centos-stream+epel-next │ 9          │  3016 │
│ 165 │ centos-stream+epel-next │ 9          │  2849 │
│ 162 │ centos-stream+epel-next │ 8          │  2827 │
│ 163 │ centos-stream+epel-next │ 8          │  2738 │
│ 144 │ epel                    │ 9          │  2380 │
│  83 │ epel                    │ 8          │  1242 │
│ 148 │ epel                    │ 9          │  1058 │
│ 146 │ epel                    │ 9          │   960 │
│ 178 │ rhel                    │ 9          │   954 │
│ 145 │ epel                    │ 8          │   736 │
│ 147 │ centos-stream           │ 9          │   612 │
│ 189 │ rhel                    │ 8          │   571 │
│ 155 │ centos-stream           │ 9          │   544 │
│  87 │ centos-stream           │ 8          │   471 │
│ 166 │ centos-stream+epel-next │ 9          │   172 │
│ 167 │ centos-stream+epel-next │ 9          │   166 │
│ 188 │ rhel                    │ 9          │   156 │
│ 164 │ centos-stream+epel-next │ 8          │   127 │
│ 187 │ rhel                    │ 8          │    70 │
└─────┴─────────────────────────┴────────────┴───────┘
(28 rows)

The temporary projects are usually created for CI purposes (e.g. Packit && pull-requests).
Data here.

[ekohl]

In #586 I've taken an approach which I think is smarter: it guesses based on the available chroots. I was not aware of the centos-stream+epel-next chroot so that could be an addition.