Add the imageID for each step to the TaskRun.Spec.Status object.

This allows users to trace the exact steps (including digest) used in each TaskRun.
This information is already available on a Pod, but we need to assume completed Pods
will be GC'ed and not available long after the run is complete.

pkg/apis/pipeline/v1alpha1/taskrun_types.go

@@ -196,6 +196,7 @@ type StepState struct {
 	corev1.ContainerState
 	Name          string `json:"name,omitempty"`
 	ContainerName string `json:"container,omitempty"`
+	ImageID       string `json:"imageID,omitempty"`
 }
 
 // CloudEventDelivery is the target of a cloud event along with the state of

pkg/status/taskrunpod.go

@@ -53,6 +53,7 @@ func UpdateStatusFromPod(taskRun *v1alpha1.TaskRun, pod *corev1.Pod, resourceLis
 				ContainerState: *s.State.DeepCopy(),
 				Name:           resources.TrimContainerNamePrefix(s.Name),
 				ContainerName:  s.Name,
+				ImageID:        s.ImageID,
 			})
 		}
 	}

pkg/status/taskrunpod_test.go

@@ -74,9 +74,11 @@ func TestUpdateStatusFromPod(t *testing.T) {
 		podStatus: corev1.PodStatus{
 			InitContainerStatuses: []corev1.ContainerStatus{{
 				// creds-init; ignored
+				ImageID: "ignored",
 			}},
 			ContainerStatuses: []corev1.ContainerStatus{{
-				Name: "step-state-name",
+				Name:    "step-state-name",
+				ImageID: "",
 				State: corev1.ContainerState{
 					Terminated: &corev1.ContainerStateTerminated{
 						ExitCode: 123,
@@ -102,11 +104,14 @@ func TestUpdateStatusFromPod(t *testing.T) {
 		podStatus: corev1.PodStatus{
 			InitContainerStatuses: []corev1.ContainerStatus{{
 				// creds-init; ignored.
+				ImageID: "ignoreme",
 			}, {
 				// git-init; ignored.
+				ImageID: "ignoreme",
 			}},
 			ContainerStatuses: []corev1.ContainerStatus{{
-				Name: "step-state-name",
+				Name:    "step-state-name",
+				ImageID: "image-id",
 				State: corev1.ContainerState{
 					Terminated: &corev1.ContainerStateTerminated{
 						ExitCode: 123,
@@ -125,6 +130,7 @@ func TestUpdateStatusFromPod(t *testing.T) {
 					}},
 				Name:          "state-name",
 				ContainerName: "step-state-name",
+				ImageID:       "image-id",
 			}},
 		},
 	}, {
@@ -138,6 +144,7 @@ func TestUpdateStatusFromPod(t *testing.T) {
 						ExitCode: 0,
 					},
 				},
+				ImageID: "image-id",
 			}},
 		},
 		want: v1alpha1.TaskRunStatus{
@@ -151,6 +158,7 @@ func TestUpdateStatusFromPod(t *testing.T) {
 					}},
 				Name:          "step-push",
 				ContainerName: "step-step-push",
+				ImageID:       "image-id",
 			}},
 			// We don't actually care about the time, just that it's not nil
 			CompletionTime: &metav1.Time{Time: time.Now()},
@@ -181,9 +189,10 @@ func TestUpdateStatusFromPod(t *testing.T) {
 	}, {
 		desc: "failure-terminated",
 		podStatus: corev1.PodStatus{
-			Phase:                 corev1.PodFailed,
+			Phase: corev1.PodFailed,
 			InitContainerStatuses: []corev1.ContainerStatus{{
 				// creds-init status; ignored
+				ImageID: "ignore-me",
 			}},
 			ContainerStatuses: []corev1.ContainerStatus{{
 				Name:    "step-failure",
@@ -209,8 +218,10 @@ func TestUpdateStatusFromPod(t *testing.T) {
 					Terminated: &corev1.ContainerStateTerminated{
 						ExitCode: 123,
 					}},
+
 				Name:          "failure",
 				ContainerName: "step-failure",
+				ImageID:       "image-id",
 			}},
 			// We don't actually care about the time, just that it's not nil
 			CompletionTime: &metav1.Time{Time: time.Now()},

test/taskrun_test.go

@@ -99,8 +99,9 @@ func TestTaskRunFailure(t *testing.T) {
 		Name:          "world",
 		ContainerName: "step-world",
 	}}
-	ignoreFields := cmpopts.IgnoreFields(corev1.ContainerStateTerminated{}, "StartedAt", "FinishedAt", "ContainerID")
-	if d := cmp.Diff(taskrun.Status.Steps, expectedStepState, ignoreFields); d != "" {
+	ignoreTerminatedFields := cmpopts.IgnoreFields(corev1.ContainerStateTerminated{}, "StartedAt", "FinishedAt", "ContainerID")
+	ignoreStepFields := cmpopts.IgnoreFields(v1alpha1.StepState{}, "ImageID")
+	if d := cmp.Diff(taskrun.Status.Steps, expectedStepState, ignoreTerminatedFields, ignoreStepFields); d != "" {
 		t.Fatalf("-got, +want: %v", d)
 	}
 }