Re: [PATCH RFC 0/3] gitlab: build containers to use in build jobs

[Thomas Huth <thuth@redhat.com>]

On 22/06/2020 17.33, Daniel P. Berrangé wrote:
> The current gitlab CI jobs are quite inefficient because they
> use the generic distro images and then apt-get/dnf install
> extra packages every time.
> 
> The other downside is that the container environment used is
> only defined in thte .gitlab-ci.yml file, so it tedious to
> reproduce locally.
> 
> We already have containers defined in tests/docker for use by
> developers building locally. We can use these for CI systems
> too if we just had a way to build them....
> 
> ...GitLab CI offers such a way. We can use docker-in-docker
> to build the images at the start of the CI cycle, and use
> the built images in later jobs.
> 
> These later jobs are now faster because they're not having
> to install any software.

Did you see any speed-up? I had a look at some pipelines, and it seems 
to me that they rather got slower now? For example, this is the system1 
pipeline before your change:

  https://gitlab.com/huth/qemu/-/jobs/610924897

and after your change:

  https://gitlab.com/huth/qemu/-/jobs/611069374

Duration went up from 35 minutes to 42 minutes.

Seems also to happen in your builds, before the change:

  https://gitlab.com/berrange/qemu/-/jobs/582995084

and after the change:

  https://gitlab.com/berrange/qemu/-/jobs/606175927

... went from 36 minutes up to 42 minutes.

Could be a coincidence due to the load on the shared runners, but it 
looks at least a little bit suspicious...

  Thomas