Fix rebase run-image resolution

[ryanbrainard]

Summary

Currently, if -run-image is not set, io.buildpacks.lifecycle.metdata[runImage.reference] is used. This does not follow the Run Image Resolution spec, which specifies using io.buildpacks.lifecycle.metdata[runImage.image] and optionally io.buildpacks.lifecycle.metdata[runImage.mirrors]. Because of this, it ends up making lifecycle rebase without the -run-image flag a no-op because the run image is pinned to the same version instead of getting the latest.

This change simplifies and unifies the behavior for before and after Platform Version 0.12 so that they both read the same run-image data type (just from different locations), and then validate and resolve mirrors the same.

Note, this is also consistent with the way pack rebase resolves run-images; however, it does not switch on the Platform Version (I didn't want to change that here).

Release notes

Fix lifecycle rebase automatic run image resolution from io.buildpacks.lifecycle.metdata to read keys runImage.image (and optionally runImage.mirrors) instead of runImage.reference.

Context

I did not see any relevant tests for this code, but please let me know if there's a test I should change or add. I did do various permutations of manual testing and it is working as expected.

[natalieparellano]

Thank you for this. It would be great if we could test this somehow - an acceptance test would probably be too heavy handed, but perhaps some of this logic could move to https://github.com/buildpacks/lifecycle/blob/main/platform/resolve_inputs.go (adding a function similar to here)

[ryanbrainard]

Thank you for this. It would be great if we could test this somehow - an acceptance test would probably be too heavy handed, but perhaps some of this logic could move to https://github.com/buildpacks/lifecycle/blob/main/platform/resolve_inputs.go (adding a function similar to here)

Yes, I would love to add a test. I just looked at resolve_inputs.go, but that doesn't look like it'll work because this needs to happen after input resolution because of some caveots with -daemon (according to the comments). Looks like platform/run_image.go would be a good place where I can at least extract out the switch statement and put some tests around it. I'll push something up soon.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.62%. Comparing base (f885774) to head (5a55111).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1305      +/-   ##
==========================================
+ Coverage   64.57%   64.62%   +0.06%     
==========================================
  Files         101      101              
  Lines        6984     6994      +10     
==========================================
+ Hits         4509     4519      +10     
  Misses       2064     2064              
  Partials      411      411              

Flag	Coverage Δ
os_linux	64.10% <100.00%> (+0.06%)	⬆️
os_windows	56.68% <100.00%> (+0.07%)	⬆️
unit	64.10% <100.00%> (+0.06%)	⬆️

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[ryanbrainard]

@natalieparellano I added a test in 5a55111