I guess we should add a command line switch to jump between the two behaviours.

I would rather enforce it. If a container image:0.0.1 has been published to the registry, surely we should not rebuild one locally that will be different? docker-pkg should use the exact same image and hence pull it, else one would need to do a version bump.

I don't have a practical example, but that has hit me several time when porting the CI containers to docker-pkg. And still it me from time to time when I lack an image locally. I ended up writing a shell one liner to sync them before running docker-pkg:

grep -R -P -h -o 'docker-registry.*:[.\d]+' jjb|sort|uniq|xargs --verbose -n1 docker pull
docker-pkg "$@"

(where the grep commands list the images as for example: docker-registry.wikimedia.org/releng/tox-mysqld:0.1.0.

Change 475843 had a related patch set uploaded (by Hashar; owner: Hashar):
[operations/docker-images/docker-pkg@master] Support docker build pull and cache

https://gerrit.wikimedia.org/r/475843

In T200720#4468242, @hashar wrote:

I would rather enforce it. If a container image:0.0.1 has been published to the registry, surely we should not rebuild one locally that will be different? docker-pkg should use the exact same image and hence pull it, else one would need to do a version bump.

I don't have a practical example, but that has hit me several time when porting the CI containers to docker-pkg. And still it me from time to time when I lack an image locally. I ended up writing a shell one liner to sync them before running docker-pkg:

docker-pkg

grep -R -P -h -o 'docker-registry.*:[.\d]+' jjb|sort|uniq|xargs --verbose -n1 docker pull
docker-pkg "$@"

(where the grep commands list the images as for example: docker-registry.wikimedia.org/releng/tox-mysqld:0.1.0.

so your proposal is to make docker-pkg do the following:
1 - check dependencies. If they're not available locally, try to pull them (at the exact tag in the changelog) from the registry. This works as long as our changelogs are updated, and it's ok I guess.

When a containers is already available locally, docker-pkg skips building it, so one always have to bump the changelog :)

Change 475843 merged by jenkins-bot:
[operations/docker-images/docker-pkg@master] Attempt to pull images before building

https://gerrit.wikimedia.org/r/475843