feat: dnf module

[xynydev]

A dnf module will eventually replace the rpm-ostree module. We should start investigating usage of dnf5 on atomic Fedora systems to determine a reasonable timeline for development of such a module.

https://fedoramagazine.org/whats-new-for-fedora-atomic-desktops-in-fedora-41/#first-step-towards-bootable-containers-dnf5-and-bootc

[fiftydinar]

It functions similarly to rpm-ostree when I tested it.

The only advantage I see is that we can enable copr repos with simpler command dnf copr enable maintainer/repo instead of manual curls.

Basically, when we would replace rpm-ostree occurences with dnf in the current module, users wouldn't notice any change in functionality except a bit different logs.

[xynydev]

Basically, when we would replace rpm-ostree occurences with dnf in the current module

I would rather create a new module called dnf. We may keep most of the configuration and even code the same, but there's no reason to keep the legacy name of rpm-ostree around.

[fiftydinar]

I'm in for making a new dnf module & announcing it to the users in blog, Discord, Mastodon & BlueSky (if it's used?).

Current structure from rpm-ostree module looks good & can be ported to dnf, except there needs to be some minor corrections in recipe format & some code logic replacements are needed.

Minor recipe format corrections

Repos

Currently, in rpm-ostree we just download the repos with curl directly to /etc/yum.repos.d/.

dnf has copr plugin to download & enable COPR repos.

• We can continue to use the same method of downloading repos using curl to /etc/yum.repos.d/
• Or switch to more native method of using dnf5 -y copr enable user/package
  • In case of dnf5 copr command usage, we can either
    • keep the same structure of repos array in recipe, so when it detects that it's copr URL, it will use dnf5 copr command
    • same as above, but users can just name the array copr: user/package instead of the full URL & we will detect that (this one is the best approach imo).
    • or add the new YAML array called repos-copr or similar, where users would just input user & package

Replacing packages

Currently, we use rpm-ostree override replace, which supports replacing packages from repo, direct URL & maybe local RPMs too.

It seems that there is no alternative for replacing packages in dnf.

dnf5 swap "${rem_packages}" "${inst_packages}" only does
rpm-ostree override remove "${rem_packages}" --install "${inst_packages}".

Everything else

Everything else looks relatively native.

[tulilirockz]

dnf5 has behavioural differences from rpm-ostree, as it probably does not install Recommends: packages by default! I ended up figuring that out when I was testing out the dnf5 migration on https://github.com/ublue-os/main and https://github.com/ublue-os/bluefin.

[tulilirockz]

rpm-ostree override replace can be replaced by dnf -y remove "${rem_packages}" && dnf -y install "${inst_packages}"

[tulilirockz]

Moving to dnf copr should be completely fine, too! There are some repos that sadly do not work rn like the ublue-os/akmods one that gets funky w/ the dnf copr behaviour (see: ublue-os/bluefin#1954)

[fiftydinar]

dnf5 has behavioural differences from rpm-ostree, as it probably does not install Recommends: packages by default! I ended up figuring that out when I was testing out the dnf5 migration on https://github.com/ublue-os/main and https://github.com/ublue-os/bluefin.

According to dnf defaults, the default is to install weak dependencies by default, just like rpm-ostree.
install_weak_deps=True

If  enabled, when a new package is about to be installed, all packages linked by weak dependency relation
(Recommends or Supplements flags) with this package will be pulled into the transaction.

I also personally didn't notice any difference in this behavior when I tested it a bit.

rpm-ostree override replace can be replaced by dnf -y remove "${rem_packages}" && dnf -y install "${inst_packages}"

That's basically what dnf swap does (except swap only supports swapping 1 package as I see now...).

But if there is no alternative, then sure, that can be also used & adjusted to match the replace behavior from recipe, without user noticing any difference.

Moving to dnf copr should be completely fine, too! There are some repos that sadly do not work rn like the ublue-os/akmods one that gets funky w/ the dnf copr behaviour (see: ublue-os/bluefin#1954)

Interesting, thanks for noting.

[fiftydinar]

I noticed in this Bazzite's PR:
https://github.com/ublue-os/bazzite/pull/1905/files

That they are using dnf5 -y upgrade --repo for replacing packages from the repo, so I think we found the command replacement for this actually.

[xynydev]

dnf has copr plugin to download & enable COPR repos.

I think we could do this simple change:

• keep the repos: array
• for each element, check if it starts with http(s)://, and use the curl method if so
• if not, give the repo to dnf5 -y copr enable and see what happens
  • if it was configured correctly, the repo should be enabled, but if there's a problem it should error out and we can print a nice error message in the logs

[fiftydinar]

• if not, give the repo to dnf5 -y copr enable and see what happens

I think a flaw in this method is support for repo files which are directly provided in /files/rpm-ostree/

So I think that my suggestion of using copr: user/package format is better.

[fiftydinar]

@gmpinder We will probably need to add --mount=type=cache,dst=/var/cache/libdnf5 in Containerfile when this gets merged

[gmpinder]

@gmpinder We will probably need to add --mount=type=cache,dst=/var/cache/libdnf5 in Containerfile when this gets merged

Sounds good, that'll be an easy addition.

[xynydev]

I think a flaw in this method is support for repo files which are directly provided in /files/rpm-ostree/

Oh right, I forgot that. If we assume copr repo names don't include the .repo suffix, but repo files all do, we use that as another way to detect it.

Adding another key would work too I guess, but then we'd have to debate the whole config structure related to that again lol.

[fiftydinar]

We should hold a bit releasing dnf module until all issues are resolved with it. rpm-ostree should be still well supported for F42 at minimum.

ublue-os/bluefin#1954 (comment)

Draft PR can be made though, to get us more ready.