podman_image: Hash Containerfile + Context directory to trigger rebuilds

[sents]

Feature request description

Currently when poman_image calculates a hash of the Containerfile that is included in the images labels. Before building it checks if an existing image with the hash in the label exists to only build on changes.
This means unless force: true the image is only rebuild when the Containerfile changes.

On the other hand just changing a file in the context directory does not trigger a rebuild. Users can currently work around this by having a comment with an incremental revision counter in the Containerfile, but this behaviour is not documented well and in my opinion counter-intuitive.

Instead we could calculate a hash by hashing the context directory and combining the hash with the existing hash of the Containerfile. This would trigger a rebuild whenever a file relevant to the container state is changed.

Suggest potential solution

A clear and concise description of what you want to happen.

Have you considered any alternatives?

A clear and concise description of any alternative solutions or features you've considered.

Additional context

Add any other context or screenshots about the feature request here.

[baude]

@mtrmac @nalind care to offer a response ? ptal

[mheon]

I would suggest the reason we're not doing this by default is that we have no idea how much is in the context directory, and hashing a (for example) 100+ gigabyte AI model to check if it's changed would result in poor performance?