deployment: building images and pushing to a registry

[ppanero]

This PR adds documentation on how to build the docker image for InvenioRDM and how to push it to several registries (GitHub, OpenShift and DockerHub).

Requires: inveniosoftware/cookiecutter-invenio-rdm#56

Question:
Since GitHub requires a password/token stored in OpenShift. Options are:

a. We can leave it as is, and make the user build the image (2-3 mins) and push it to a registry.
b. Build the default image (that we have to do anyway) and push it to DockerHub so everybody has access to pull it.

Note: if we opt for a we can just push our image to CERN OpenShift or CERN GitLab registry.

WDYT? @lnielsen @zzacharo @fenekku

Decision will close inveniosoftware/demo-inveniordm#7

[zzacharo]

In general nice job! Some minor comments here and there :)

[ppanero]

@zzacharo Thanks! fixed the typos and re-wrote the part of the image yaml. Please resolve the comment if you are okay with it :)

[fenekku]

Those are good instructions. What could we do to separate the Openshift specific instructions, from the other means specific instructions, from general instructions that are valid for all? I am tempted to have a separate Openshift folder with the many documentation files in it and other folders for other technologies...

[ppanero]

@fenekku I understand that we have many "OpenShift" related documentation. But at the moment is the only "production" deployment that we have, and is the only technology we support (for now). I think at this point spreading documentation is a bit of an overkill, since we do not know 10% what are the changes that are gonna be needed afterwards.

Once we have support for something else (e.g. bare Kube) I agree with the refactoring, but having an idea of what is different to refactor.

Answered the two questions, thanks for the review!

[fenekku]

Sure... Our IT is probably not going to use Openshift, so that was a partly selfish ask 😸 . We'll see if it's easy enough to translate.