Enhance error messages around image to tag resolving. (#5920)

* Enhance error messages around image to tag resolving.

We currently surface the plain error returned from the tag resolution without further explanation. This adds wrapping around those errors to explain in which step it fails and adds wrapping around the outer layer to make sure the user gets enough context to be able to tell what exactly failed.

Fixes #5410

* Make the linter happy.

pkg/reconciler/revision/resolve.go

@@ -92,7 +92,7 @@ func (r *digestResolver) Resolve(
 	registriesToSkip sets.String) (string, error) {
 	kc, err := k8schain.New(r.client, opt)
 	if err != nil {
-		return "", err
+		return "", fmt.Errorf("failed to initialize authentication: %w", err)
 	}
 
 	if _, err := name.NewDigest(image, name.WeakValidation); err == nil {
@@ -102,7 +102,7 @@ func (r *digestResolver) Resolve(
 
 	tag, err := name.NewTag(image, name.WeakValidation)
 	if err != nil {
-		return "", err
+		return "", fmt.Errorf("failed to parse image name %q into a tag: %w", image, err)
 	}
 
 	if registriesToSkip.Has(tag.Registry.RegistryStr()) {
@@ -114,7 +114,7 @@ func (r *digestResolver) Resolve(
 	}
 	desc, err := remote.Get(tag, remote.WithTransport(r.transport), remote.WithAuthFromKeychain(kc), remote.WithPlatform(platform))
 	if err != nil {
-		return "", err
+		return "", fmt.Errorf("failed to fetch image information: %w", err)
 	}
 
 	// TODO(#3997): Use remote.Get to resolve manifest lists to digests as well
@@ -123,11 +123,11 @@ func (r *digestResolver) Resolve(
 	case types.OCIImageIndex, types.DockerManifestList:
 		img, err := desc.Image()
 		if err != nil {
-			return "", err
+			return "", fmt.Errorf("failed to get image reference: %w", err)
 		}
 		dgst, err := img.Digest()
 		if err != nil {
-			return "", err
+			return "", fmt.Errorf("failed to get image digest: %w", err)
 		}
 		return fmt.Sprintf("%s@%s", tag.Repository.String(), dgst), nil
 	default:

pkg/reconciler/revision/revision.go

@@ -18,6 +18,7 @@ package revision
 
 import (
 	"context"
+	"fmt"
 	"reflect"
 	"strings"
 
@@ -142,6 +143,7 @@ func (c *Reconciler) reconcileDigest(ctx context.Context, rev *v1alpha1.Revision
 	digest, err := c.resolver.Resolve(rev.Spec.GetContainer().Image,
 		opt, cfgs.Deployment.RegistriesSkippingTagResolving)
 	if err != nil {
+		err = fmt.Errorf("failed to resolve image to digest: %w", err)
 		rev.Status.MarkContainerHealthyFalse(v1alpha1.ContainerMissing,
 			v1alpha1.RevisionContainerMissingMessage(
 				rev.Spec.GetContainer().Image, err.Error()))

pkg/reconciler/revision/revision_test.go

@@ -261,20 +261,20 @@ func (r *fixedResolver) Resolve(_ string, _ k8schain.Options, _ sets.String) (st
 }
 
 type errorResolver struct {
-	error string
+	err error
 }
 
 func (r *errorResolver) Resolve(_ string, _ k8schain.Options, _ sets.String) (string, error) {
-	return "", errors.New(r.error)
+	return "", r.err
 }
 
 func TestResolutionFailed(t *testing.T) {
 	ctx, cancel, _, controller, _ := newTestController(t)
 	defer cancel()
 
 	// Unconditionally return this error during resolution.
-	errorMessage := "I am the expected error message, hear me ROAR!"
-	controller.Reconciler.(*Reconciler).resolver = &errorResolver{errorMessage}
+	innerError := errors.New("i am the expected error message, hear me ROAR!")
+	controller.Reconciler.(*Reconciler).resolver = &errorResolver{innerError}
 
 	rev := testRevision()
 	config := testConfiguration()
@@ -295,7 +295,7 @@ func TestResolutionFailed(t *testing.T) {
 			Status: corev1.ConditionFalse,
 			Reason: "ContainerMissing",
 			Message: v1alpha1.RevisionContainerMissingMessage(
-				rev.Spec.GetContainer().Image, errorMessage),
+				rev.Spec.GetContainer().Image, "failed to resolve image to digest: "+innerError.Error()),
 			LastTransitionTime: got.LastTransitionTime,
 			Severity:           apis.ConditionSeverityError,
 		}