[Starlingx-discuss] [Build] CentOS-8 dnf support for modularity
scott.little at windriver.com
Wed Nov 25 16:00:51 UTC 2020
Centos 8 feature branch can't currently build because dnf by default
expects module data to be included in repo data.
A good link explaining modularity is here
It appears to be a way to groups of packages, and to support multiple
versions of the package group from a common base os. e.g. They are
likely concurrently supporting python2 and python3 through modularity.
The build tooling described to support modularity is entirely centered
around a fedora hosted build service. My limited exploration of the
subject has not yet found a way to build independently of the fedory
build service. CentOS specific documentation is also something wasn't
able to find quickly.
Does StarlingX need to support modularity? This needs to be considered
at multiple stages.
1) CENGN Mirroring.
CENGN probably needs to support modularity in it's mirroring process
before any consideration of supporting modularity in the rest of the
build process can be considered.
2) Download phase.
Our downloads are currently driven by 'lst' files that state
specific versions of a packages. We don't use non-versioned packages,
nor meta-packages, nor capabilities. Modularity seems like just another
way to map an abstraction to a set of packages, and doesn't allow us to
control with specificity which versions of those packages we take. If
we wish to retain that level of control going forward, modularity
doesn't help us download the packages we want
3) Build phase
generate-centos-repo.sh generates a single repo from all the
carefully selected rpms that we have downloaded. At this stage, I see
no need to support modularity whatsoever.
Fu Yong's update tries to support modularity within the Centos 8 feature
It appears to be re-introducing modularity at stage 3, ignoring
stages 1 and 2. It is using a modules.yaml of unknown origin. It names
package we don't have. For packages that we do have, it would have to be
kept in sync with our lst files. Keeping up with packages we build for
ourselves is a whole other matter. It does not live in stx-tools. And
at the end of the day, we don't need it to build the iso beyond telling
dnf to not fail of module data is not found.
My proposed updates to master branch to support building Centos 7 based
distro from a Centos 8 (or 7) build environment ...
My approach is to not even attempt to support modularity at this
time. We don't need it. We can explore supporting it at a later time.
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