fix: populate role ARN from stack outputs on NoChangeError

IAMRoleUpdater.Update returns an empty roleArn to the caller when
CFN has nothing to update and the config uses roleName (no roleARN).
Pull the ARN from the existing stack outputs instead.

Author: cs-mehta

pkg/actions/podidentityassociation/iam_role_updater.go

@@ -52,6 +52,9 @@ func (u *IAMRoleUpdater) Update(ctx context.Context, podIdentityAssociation api.
 		var noChangeErr *manager.NoChangeError
 		if errors.As(err, &noChangeErr) {
 			logger.Info("IAM resources for %s (pod identity association ID: %s) are already up-to-date", podIdentityAssociation.NameString(), podIdentityAssociationID)
+			if err := populateRoleARN(rs, stack); err != nil {
+				return "", false, err
+			}
 			return podIdentityAssociation.RoleARN, false, nil
 		}
 		return "", false, fmt.Errorf("updating IAM resources for pod identity association: %w", err)

pkg/actions/podidentityassociation/updater_test.go

@@ -433,13 +433,21 @@ var _ = Describe("Pod Identity Update", func() {
 						ServiceAccountName: "aws-node",
 					},
 				}
+				describeStackOutputs := []cfntypes.Output{
+					{
+						OutputKey:   aws.String(outputs.IAMServiceAccountRoleName),
+						OutputValue: aws.String("arn:aws:iam::1234567:role/Role"),
+					},
+				}
 				mockListStackNames(stackManager, podIdentifiers)
 				for _, options := range []mockOptions{
 					{
-						podIdentifier: podIdentifiers[0],
+						podIdentifier:        podIdentifiers[0],
+						describeStackOutputs: describeStackOutputs,
 					},
 					{
-						podIdentifier: podIdentifiers[1],
+						podIdentifier:        podIdentifiers[1],
+						describeStackOutputs: describeStackOutputs,
 					},
 				} {
 					mockCalls(stackManager, eksAPI, options)
@@ -458,6 +466,72 @@ var _ = Describe("Pod Identity Update", func() {
 			},
 		}),
 
+		Entry("IAM no changes but disableSessionTags triggers EKS update with roleName resolving ARN from stack", updateEntry{
+			podIdentityAssociations: []api.PodIdentityAssociation{
+				{
+					Namespace:          "default",
+					ServiceAccountName: "default",
+					RoleName:           "my-custom-role",
+					DisableSessionTags: aws.Bool(true),
+				},
+			},
+			mockCalls: func(stackManager *managerfakes.FakeStackManager, eksAPI *mocksv2.EKS) {
+				podIdentifier := podidentityassociation.Identifier{
+					Namespace:          "default",
+					ServiceAccountName: "default",
+				}
+				mockListStackNames(stackManager, []podidentityassociation.Identifier{podIdentifier})
+
+				stackName := makeIRSAv2StackName(podIdentifier)
+				associationID := fmt.Sprintf("%x", sha1.Sum([]byte(stackName)))
+				resolvedRoleARN := "arn:aws:iam::1234567:role/my-custom-role"
+
+				mockListPodIdentityAssociations(eksAPI, podIdentifier, []ekstypes.PodIdentityAssociationSummary{
+					{
+						AssociationId: aws.String(associationID),
+					},
+				}, nil)
+				eksAPI.On("DescribePodIdentityAssociation", mock.Anything, &eks.DescribePodIdentityAssociationInput{
+					AssociationId: aws.String(associationID),
+					ClusterName:   aws.String(clusterName),
+				}).Return(&eks.DescribePodIdentityAssociationOutput{
+					Association: &ekstypes.PodIdentityAssociation{
+						AssociationId: aws.String(associationID),
+						RoleArn:       aws.String(resolvedRoleARN),
+					},
+				}, nil)
+
+				stackManager.DescribeStackReturns(&cfntypes.Stack{
+					StackName: aws.String(stackName),
+					Outputs: []cfntypes.Output{
+						{
+							OutputKey:   aws.String(outputs.IAMServiceAccountRoleName),
+							OutputValue: aws.String(resolvedRoleARN),
+						},
+					},
+					Capabilities: []cfntypes.Capability{cfntypes.CapabilityCapabilityIam, cfntypes.CapabilityCapabilityNamedIam},
+				}, nil)
+
+				stackManager.MustUpdateStackReturns(&manager.NoChangeError{
+					Msg: "no changes found",
+				})
+
+				eksAPI.On("UpdatePodIdentityAssociation", mock.Anything, &eks.UpdatePodIdentityAssociationInput{
+					AssociationId:      aws.String(associationID),
+					ClusterName:        aws.String(clusterName),
+					RoleArn:            aws.String(resolvedRoleARN),
+					DisableSessionTags: aws.Bool(true),
+				}).Return(&eks.UpdatePodIdentityAssociationOutput{}, nil)
+			},
+
+			expectedCalls: func(stackManager *managerfakes.FakeStackManager, eksAPI *mocksv2.EKS) {
+				Expect(stackManager.ListPodIdentityStackNamesCallCount()).To(Equal(1))
+				Expect(stackManager.DescribeStackCallCount()).To(Equal(1))
+				Expect(stackManager.MustUpdateStackCallCount()).To(Equal(1))
+				eksAPI.AssertExpectations(GinkgoT())
+			},
+		}),
+
 		Entry("update pod identity association with cross-account access", updateEntry{
 			podIdentityAssociations: []api.PodIdentityAssociation{
 				{