fix: specifying platforms in ko builder

[gsquared94]

Related: #6120

Description

The ko builder already supports building multi-platform and cross-platform images. This PR removes the property artifact.ko.platforms from the config schema and uses artifact.platforms which makes it conform with all the other builders.

[codecov]

Codecov Report

Merging #7135 (25842bc) into main (290280e) will decrease coverage by 2.07%.
The diff coverage is 56.96%.

@@            Coverage Diff             @@
##             main    #7135      +/-   ##
==========================================
- Coverage   70.48%   68.40%   -2.08%     
==========================================
  Files         515      560      +45     
  Lines       23150    26239    +3089     
==========================================
+ Hits        16317    17950    +1633     
- Misses       5776     7054    +1278     
- Partials     1057     1235     +178     

Impacted Files	Coverage Δ
cmd/skaffold/app/cmd/deploy.go	52.00% <ø> (-1.85%)	⬇️
cmd/skaffold/app/cmd/dev.go	84.61% <0.00%> (ø)
cmd/skaffold/app/cmd/render.go	36.66% <0.00%> (-4.72%)	⬇️
cmd/skaffold/skaffold.go	0.00% <0.00%> (ø)
cmd/skaffold/app/cmd/inspect_tests.go	62.50% <14.28%> (-1.14%)	⬇️
cmd/skaffold/app/cmd/lsp.go	28.12% <28.12%> (ø)
cmd/skaffold/app/cmd/fix.go	68.85% <40.00%> (-7.62%)	⬇️
cmd/skaffold/app/cmd/lint.go	42.85% <42.85%> (ø)
cmd/skaffold/app/cmd/find_configs.go	48.88% <50.00%> (+0.24%)	⬆️
cmd/skaffold/app/skaffold.go	76.19% <70.00%> (-8.43%)	⬇️
... and 215 more

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[halvards]

Thanks for doing this @gsquared94.

There's one regression: The ko builder supports the value all in the platforms field: https://skaffold.dev/docs/pipeline-stages/builders/ko/#multi-platform-images

Using all results in ko building for all platforms supported by the base image (ko docs here: https://github.com/google/ko#multi-platform-images). It's a useful feature, and it'd be great to retain it. I appreciate that this might mean having to support it for all the builders, or at least handle all in a sensible way.

[gsquared94]

Thanks for doing this @gsquared94.

There's one regression: The ko builder supports the value all in the platforms field: https://skaffold.dev/docs/pipeline-stages/builders/ko/#multi-platform-images

Using all results in ko building for all platforms supported by the base image (ko docs here: https://github.com/google/ko#multi-platform-images). It's a useful feature, and it'd be great to retain it. I appreciate that this might mean having to support it for all the builders, or at least handle all in a sensible way.

Thanks for the quick review @halvards . I've fixed the missing parsing logic for all platform value.
Tested against the sample integration/examples/ko, by running:

skaffold build --platform=all --default-repo=gcr.io/k8s-skaffold

[halvards]

LGTM. We'll have to update the ko builder documentation page before the next release, since it references the old config field.

[gsquared94]

LGTM. We'll have to update the ko builder documentation page before the next release, since it references the old config field.

updated the docs.

[tejal29]

LGTM