Make buildSRPMFromSCM faster?

[Dennis Gilmore]

On Mon, 21 Jul 2014 13:58:49 -0500
Dennis Gilmore <dennis at ausil.us> wrote:

> On Sat, 19 Jul 2014 12:30:38 +0100
> "Richard W.M. Jones" <rjones at redhat.com> wrote:
> 
> > 
> > The first step of most Koji builds is buildSRPMFromSCM, where a
> > .src.rpm file is built from the git repo.
> > 
> > Currently this involves completely building a mock buildroot
> > containing all the BuildRequires, and running `rpmbuild -bs'.  This
> > takes many minutes (especially when arm is chosen as a builder).
> > 
> > It seems the reason for this is because the spec file has to be
> > fully parsed in order to work out the Source lines.  Since Source
> > lines might depend on RPM macros which might depend on any
> > BuildRequire'd package, every BR package must be installed in the
> > mock root. `rpmbuild -bs' takes seconds because it just bundles all
> > the Source files with the spec file into an SRPM.
> > 
> > Is this really necessary?
> This is not at all true. we have a minimal buildroot that is installed
> for every single build, the buildroot packages are the same across all
> builds. there is no BuildRequires pulled in until the buildArch task
> 
> 
> > Two shortcuts seem possible:
> > 
> > (1) Limit the use of macros in Source lines, so that only a simple,
> > standard, perhaps pre-cached buildroot can be used.
> > 
> > (2) Perhaps uglier: Just build an SRPM that contains everything in
> > dist-git + everything in the lookaside cache, and hope for the
> > best ...
> This is what we do now.
> 
> Dennis

we could make it faster by switching to a fedpkg wrapper that was just
a shell script to get the sources. fedpkg has a lot of deps, we would
make what needs installed smaller.

Dennis