[FR]: squash_tars rule

[sin-ack]

What is the current behavior?

I am using rules_apt to download a set of packages from Debian/Ubuntu repositories, so that I can add those packages to my oci_image as a layer. The problem is that each package has a set of dependencies on its own. In total, we have 67 dependencies right now, which when loaded into Docker as layer-per-package causes it to balk with "too many layers".

Describe the feature

A rule called squash_tars, which takes a set of .tar files as input, and returns a single .tar file. The contents are extracted in input file order and then re-compressed into a single file.

I have a basic implementation of this already and intend to create a PR. I wanted to open an issue first to see whether it would be desired.

[thesayyn]

I recommend https://github.com/GoogleContainerTools/rules_distroless/blob/main/docs/rules.md#flatten, you could alternatively just use a genrule that depends on the tar toolchain.

[sin-ack]

Thanks for the recommendation. I'll use that instead.

[jjmaestro]

#870 also mentions this... I also think it's a pretty useful functionality to have in a "generic" / utilities library. @thesayyn would you consider moving flatten to bazel-lib?