Fix func build/deploy validation: Add early validation for conflicting --image and --registry flags

[RayyanSeliya]

Changes

• 🐛 Fix confusing UX when using conflicting --image and --registry flags
• 🧹 Implement 2-layer error system for image/registry validation
• 🎁 Add clear guidance for resolving flag conflicts

/kind enhancement

Fixes #3065

Solution:

Implement a 2-layer error system:

• Layer 1 (Technical): Return ErrConflictingImageAndRegistry from validation in pkg/functions/errors.go
• Layer 2 (CLI): Catch the error in cmd/build.go and cmd/deploy.go and wrap with user-friendly guidance

Implementation Details:

• Add validation logic in buildConfig.Validate() and deployConfig.Validate() methods
• Use strings.HasPrefix() to check if image starts with registry (allows subnamespaces)
• Maintain backward compatibility with existing test cases
• Ensure error messages are consistent between build and deploy commands

Release Note

func build and func deploy commands now validate conflicting --image and --registry flags before starting the build process, providing clear error messages and actionable guidance instead of misleading build failures.

[knative-prow]

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[knative-prow]

Hi @RayyanSeliya. Thanks for your PR.

I'm waiting for a knative member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 45 lines in your changes missing coverage. Please review.
✅ Project coverage is 40.60%. Comparing base (7cb458e) to head (73b89f5).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/build.go	0.00%	26 Missing and 1 partial ⚠️
cmd/deploy.go	0.00%	18 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (7cb458e) and HEAD (73b89f5). Click for more details.

HEAD has 4 uploads less than BASE

Flag	BASE (7cb458e)	HEAD (73b89f5)
	1	0
unit-tests	3	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3066       +/-   ##
===========================================
- Coverage   56.94%   40.60%   -16.34%     
===========================================
  Files         133      116       -17     
  Lines       17094    16582      -512     
===========================================
- Hits         9734     6733     -3001     
- Misses       6451     9034     +2583     
+ Partials      909      815       -94     

Flag	Coverage Δ
e2e-tests	40.60% <0.00%> (+1.19%)	⬆️
unit-tests	?

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[RayyanSeliya]

I think i am missing some edge cases @gauron99 @lkingland please point out if any the test are still failing :(

[gauron99]

im gonna take a look tomorrow

[RayyanSeliya]

Sure no worries !! Good night !

[gauron99]

perhaps we could simply check that -registry and --image are not given together at all? Image takes precedence now which is correct. But we want to avoid having the need to remove FUNC_REGISTRY or your registry in config file when trying to once specify --image for a different registry.
In other words --image should just take precedence and work even when FUNC_REGISTRY is specified BUT --image and --registry could just return an error saying "just choose one or the other" for simplicity?

Otherwise you would need to check both registries, determine what parts image contains and prepend (which I dont think works currently? check my other comment) and that would require a bit more work and consideration.

@lkingland WDYT?

[gauron99]

are they really prepended?

[gauron99]

❯ func build --image mine --registry quay.io/dfridric
Building function image
Still building
🙌 Function built: mine

[knative-prow-robot]

PR needs rebase.

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