Document a `verify` script pattern

Update 2022 by Erik

My understanding is that we don’t look to implement a feature in repo2docker related to a pattern, but that we may wish to document ideas like this. An example to reference could be this from pangeo-stacks: https://github.com/jupyterhub/repo2docker/issues/93#issuecomment-502821794

Original post

I think for many people it’d be useful to run some simple tests whenever their r2d image is built. This is similar to postBuild (and the same behavior could be done w/ a few assert statements at the end of one of these files), but I wonder if it’d be worth having a file that specifically has the job of “throw a tests aren't passing error” so that the user knows their code isn’t working.

Alternatively, we could try to set guidelines for this in the documentation, basically include a section on how to ensure your container runs after it builds. Thoughts?

[jhamman]

@alando46 and I have been discussing this idea a bit in https://github.com/pangeo-data/pangeo/issues/544. Something users could do today is include a test suite in their repo and test a built image like this:

docker run -i -t ${IMAGE_NAME} "py.test"

I suppose a generic verify interface would be useful as well if you wanted to add this as an option to repo2docker cli or binderhub in someway.

[jhamman]

FWIW, the verify script is what we started using in pangeo-stacks.

• Here’s an example: https://github.com/pangeo-data/pangeo-stacks/blob/master/pangeo-notebook/binder/verify
• And its execution as part of our CI workflow: https://github.com/pangeo-data/pangeo-stacks/blob/0425c2df72c0badd2f37dde4b6f02f2a55b8de2b/build.py#L77-L88