Add an option to recipe to blacklist packages from buildcache

[simonpintarelli]

When building packages from a git branch, for example sirius@git.my-branch=develop, the package will be fetched from buildcache even if the branch has been updated in the meantime.

Is it possible to add an option to config.yaml or environments.yaml to exclude packages from the buildcache?

[bcumming]

In cases like this, ideally you want to never push @branch builds to the build cache in the first place. So should the option be applied here: https://github.com/eth-cscs/stackinator/blob/master/stackinator/templates/Makefile.environments#L20-L24

We already try to exclude cuda and nvhpc from the build cache, because

• copying them to the cache takes ~30 minutes sometimes
• because they are binary blobs, installing them fresh each time takes hardly any more time than installing from the cache

However, this feature broke at some point - I could add support for optionally excluding packages by name when I fix the this?

[simonpintarelli]

Thank you. It's not an important feature, but nice to have. I'll have a look too, perhaps its possible to exclude packages installed via pkg@git.<branch>=..., excluding package by name via an additional entry would be the 2nd best option.