Implement crane index subcommand

[jonjohnsonjr]

crane index filter allows platform-based filtering of manifests in an index. This is primarily useful for folks who want to use only some entries in a base image without having to copy irrelevant platforms.

crane index append allows appending manifests to an existing index or creating a new index from scratch.

Fixes #1144
Fixes #1143
Fixes #1557

See also:

• Improve append command - ease the process to push manifests to remote registries from a set of images #891
• RFC: crane amend #1144 (comment)

[codecov-commenter]

Codecov Report

Merging #1561 (9b77df4) into main (e04520b) will increase coverage by 0.15%.
The diff coverage is 82.14%.

@@            Coverage Diff             @@
##             main    #1561      +/-   ##
==========================================
+ Coverage   72.75%   72.91%   +0.15%     
==========================================
  Files         118      118              
  Lines        9236     9408     +172     
==========================================
+ Hits         6720     6860     +140     
- Misses       1831     1856      +25     
- Partials      685      692       +7     

Impacted Files	Coverage Δ
pkg/v1/config.go	31.57% <0.00%> (-43.43%)	⬇️
pkg/v1/remote/write.go	62.84% <62.50%> (+0.15%)	⬆️
pkg/v1/remote/descriptor.go	72.34% <67.56%> (-1.51%)	⬇️
internal/cmd/edit.go	54.12% <85.00%> (+0.64%)	⬆️
pkg/registry/manifest.go	94.04% <100.00%> (+1.83%)	⬆️
pkg/registry/registry.go	100.00% <100.00%> (ø)
pkg/v1/platform.go	100.00% <100.00%> (ø)

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[tianon]

I gave Jon badly worded feedback that made him split the one command he'd created into two separate commands 😭

"filter" for something that mutates seems like an odd word choice - his original choice was crane amend, and I thought that was potentially a large source of user confusion when it'll appear right next to crane append (and "append" vs "amend" is not great - they're very related words but the two commands will do very different things and even operate on entirely different sets of objects)

IMO something like crane index amend would be totally reasonable, but it feels a little weird next to crane manifest, crane config, and crane blob that are all single-object-type getters and it feels like overkill to crane index just for a single subcommand so I don't know what to recommend 😞

I'm sorry I made this harder Jon 😭 ❤️ 🙇

[imjasonh]

Don't beat yourself up @tianon 😄, I recommended index filter and index append because they feel like two separate operations to me. One removes manifests from an index, one adds them.

I think I like having crane index as a place to do index-specific operations. A lot of crane implicitly deals with images (pull, append, export), but I don't think it's worth having a crane image sub-tree. Agnostic stuff like manifest, digest, blob also make sense at the root and should stay there.

Since index append is different than (image) append, I think that's a good place to start filling out an index-specific sub-command.

[jonjohnsonjr]

@thesayyn FYI, would be interested in your feedback.

I'm not sure if I'm ready to go full-on CEL integration :P

[thesayyn]

sorry, I was off last week due to the earthquake. this looks as good as it could get without having a DSL or using CEL.