Emit an event if overwriting PodTemplate affinity

pkg/reconciler/taskrun/taskrun.go

@@ -629,8 +629,13 @@ func (c *Reconciler) createPod(ctx context.Context, tr *v1beta1.TaskRun, rtr *re
 		return nil, fmt.Errorf("translating TaskSpec to Pod: %w", err)
 	}
 
-	return c.KubeClientSet.CoreV1().Pods(tr.Namespace).Create(pod)
-
+	pod, err = c.KubeClientSet.CoreV1().Pods(tr.Namespace).Create(pod)
+	if err == nil && willOverwritePodSetAffinity(tr) {
+		if recorder := controller.GetEventRecorder(ctx); recorder != nil {
+			recorder.Eventf(tr, corev1.EventTypeWarning, "PodAffinityOverwrite", "Pod template affinity is overwritten by affinity assistant for pod %q", pod.Name)
+		}
+	}
+	return pod, err
 }
 
 type DeletePod func(podName string, options *metav1.DeleteOptions) error
@@ -731,3 +736,13 @@ func storeTaskSpec(ctx context.Context, tr *v1beta1.TaskRun, ts *v1beta1.TaskSpe
 	}
 	return nil
 }
+
+// willOverwritePodSetAffinity returns a bool indicating whether the
+// affinity for pods will be overwritten with affinity assistant.
+func willOverwritePodSetAffinity(taskRun *v1beta1.TaskRun) bool {
+	var podTemplate v1beta1.PodTemplate
+	if taskRun.Spec.PodTemplate != nil {
+		podTemplate = *taskRun.Spec.PodTemplate
+	}
+	return taskRun.Annotations[workspace.AnnotationAffinityAssistantName] != "" && podTemplate.Affinity != nil
+}

pkg/reconciler/taskrun/taskrun_test.go

@@ -3026,3 +3026,68 @@ func Test_storeTaskSpec(t *testing.T) {
 		t.Fatalf(diff.PrintWantGot(d))
 	}
 }
+
+func TestWillOverwritePodAffinity(t *testing.T) {
+	affinity := &corev1.Affinity{
+		PodAffinity: &corev1.PodAffinity{
+			RequiredDuringSchedulingIgnoredDuringExecution: []corev1.PodAffinityTerm{
+				{
+					Namespaces: []string{"tekton-pipelines"},
+				},
+			},
+		},
+	}
+	affinityAssistantName := "pipeline.tekton.dev/affinity-assistant"
+
+	tcs := []struct {
+		name                string
+		hasTemplateAffinity bool
+		annotations         map[string]string
+		expected            bool
+	}{
+		{
+			name:     "no settings",
+			expected: false,
+		},
+		{
+			name: "no PodTemplate affinity set",
+			annotations: map[string]string{
+				affinityAssistantName: "affinity-assistant",
+			},
+			expected: false,
+		},
+		{
+			name:                "affinity assistant not set",
+			hasTemplateAffinity: true,
+			expected:            false,
+		},
+		{
+			name:                "PodTemplate affinity will be overwritten with affinity assistant",
+			hasTemplateAffinity: true,
+			annotations: map[string]string{
+				affinityAssistantName: "affinity-assistant",
+			},
+			expected: true,
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			tr := &v1beta1.TaskRun{
+				Spec: v1beta1.TaskRunSpec{
+					PodTemplate: &v1beta1.PodTemplate{},
+				},
+				ObjectMeta: metav1.ObjectMeta{
+					Annotations: tc.annotations,
+				},
+			}
+			if tc.hasTemplateAffinity {
+				tr.Spec.PodTemplate.Affinity = affinity
+			}
+
+			if got := willOverwritePodSetAffinity(tr); got != tc.expected {
+				t.Errorf("expected: %t got: %t", tc.expected, got)
+			}
+		})
+	}
+}