Allow setting Content-Type in crane edit manifest

[jonjohnsonjr]

This uses the --media-type flag.

[tianon]

Can this new flag default to the mediaType in my edited document? 🥺

(I want to be able to convert docs from Docker media types to OCI media types 🙇)

Edit: Jon is faster than I am! 😂

[codecov-commenter]

Codecov Report

Merging #1551 (4d05fe1) into main (da1008f) will decrease coverage by 0.34%.
The diff coverage is 56.54%.

@@            Coverage Diff             @@
##             main    #1551      +/-   ##
==========================================
- Coverage   73.07%   72.74%   -0.34%     
==========================================
  Files         117      118       +1     
  Lines        9082     9241     +159     
==========================================
+ Hits         6637     6722      +85     
- Misses       1780     1833      +53     
- Partials      665      686      +21     

Impacted Files	Coverage Δ
pkg/v1/manifest.go	100.00% <ø> (ø)
pkg/v1/remote/delete.go	58.62% <ø> (ø)
pkg/v1/mutate/mutate.go	69.01% <10.52%> (-3.80%)	⬇️
pkg/v1/remote/referrers.go	40.00% <40.00%> (ø)
pkg/v1/remote/write.go	62.69% <55.95%> (-1.42%)	⬇️
pkg/v1/remote/descriptor.go	73.84% <61.53%> (-0.44%)	⬇️
internal/cmd/edit.go	54.12% <85.00%> (+0.64%)	⬆️
pkg/v1/mutate/image.go	69.56% <100.00%> (+0.33%)	⬆️
pkg/v1/mutate/index.go	79.33% <100.00%> (+0.34%)	⬆️
pkg/v1/remote/options.go	77.77% <100.00%> (+1.41%)	⬆️
... and 4 more

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[tianon]

I suppose I should report back that I successfully tested this PR for converting an image from Docker media types to OCI media types and all went well. 😄

[imjasonh]

I suppose I should report back that I successfully tested this PR for converting an image from Docker media types to OCI media types and all went well. 😄

Would a command just to OCIfy a docker image be helpful? That's something we've found a need for in the past and then punted on.

[tianon]

Hmmm, as a flag to crane cp maybe? I don't think I'd personally use it, though, since it's just as easy to munge the 2-3 media types myself and I don't actually do this kind of munging very often (and hopefully even less over time!)

I ran into this while testing something else the first time, and it was only the second time that I was trying to OCI-ify an existing image that I decided to really bug Jon about it in earnest since it seemed like an easy win for the overall ergonomics of crane edit matching my expectations of how it was about to work. 😂

[tianon]

Mostly just to make Jon cringe, I'd be happy to write a jq one-liner for the docs so you can suggest users do crane manifest ... | jq '...' | crane edit manifest ... if that's helpful 😄

Edit: I need to stop trying to have coherent thoughts in the evenings and the mornings apparently - that trivial version wouldn't work recursively, which limits the usefulness a bit (and jq is probably overkill; sed would do the trick pretty reasonably) 🤔

[jonjohnsonjr]

Would a command just to OCIfy a docker image be helpful? That's something we've found a need for in the past and then punted on.

I'm 99% sure there's a PR to do this somewhere.

[tianon]

Would a command just to OCIfy a docker image be helpful? That's something we've found a need for in the past and then punted on.

I'm 99% sure there's a PR to do this somewhere.

Looks like that's #1293 (also relevant is #1245)