Invalidate cache if the version baked into CLI is newer

[jdolitsky]

If we update the builtin-mappings.yaml file with new entries, it is not used by default if there is existing files inside the XDG_CACHE etc.

We should do something to either invalidate the cache based on timestamp, or something to prevent future travelers from being confused why mappings arent being applied during testing.

As a workaround, people can use the --mappings flag:

go run . --mappings pkg/dfc/builtin-mappings.yaml Dockerfile

[jdolitsky]

As a workaround for now, users can just run dfc --update after installation

[iamrajiv]

I can try to fix this, @jdolitsky. I’ve faced similar issues in one of my projects. Applications often compare the user’s cached configuration file with the new default one after an upgrade. One approach I believe could be the most robust is using hashes. This ensures the user always gets the correct data based on the actual content, without relying on manual version updates or potentially unreliable timestamps. However, I’d like confirmation on this approach, or if you have any other suggestions in mind.

[jdolitsky]

@iamrajiv youre welcome to try whatever approach you have in mind for this! Thank you

dfc currently works without anything in the cache. So perhaps to solve with hashes, we need to attempt to copy the builtin mappings into the cache if it doesnt exist, so that when we upgrade we can check to see if that builtin hash is already present.