Add continuous integration for running docker-build

[timabbott]

This will make it possible to test pull requests for whether they build via CI, which would save time in testing/debugging the images. And I don't think it should be super hard.

Which CI platform is best for doing Docker testing?

[timabbott]

Having played with this more, what I want the CI to do is not just build the image, but actually boot it and create a Zulip organization (using the self-signed cert flow or something). That would be a really good end-to-end test of this image.

[OliverEvans96]

If you do still want to build the images via CI, you might consider kaniko. I haven't used it with github, but I had some success with gitlab, as described in https://docs.gitlab.com/ee/ci/docker/using_kaniko.html

[timabbott]

Hmm; does that have a cloud service? It looks like software we'd need to host somewhere.

[OliverEvans96]

Yeah, you can self-host or use their instance @ https://gitlab.com/

[rht]

Yeah, you can self-host or use their instance @ https://gitlab.com/

As in, retain the repo hosting in github, but enable the CI/CD in gitlab? https://docs.gitlab.com/ee/ci/ci_cd_for_external_repos/index.html