Fails to natively decompress xz indices on macOS ("unable to download package index")

[themacguffinman]

Package index fetching logic depends on the xz command to decompress Packages.xz (see

rules_distroless/apt/private/package_index.bzl

Line 8 in 9da4ee5

file_types = {"xz": ["xz", "--decompress"], "gz": ["gzip", "-d"]}

)

macOS doesn't natively have an xz command, the native way to decompress xz files is surprisingly gzip -d Packages.xz (gzip in macOS is a non-standard Apple variant).

It's fairly easy to workaround by installing xz (brew install xz) so the xz command works. Ideally rules_distroless should use the native macOS command automatically but documenting this macOS dependency in the README would be helpful too.

[thesayyn]

Ideally we'd want to use something like zstd to decompress and not depend on host binaries, but unfortunately i don't have the time to invest into this.