kubelet container status calculation doesn't handle suddenly missing data properly

pkg/kubelet/kubelet_test.go

@@ -1607,6 +1607,38 @@ func TestGenerateAPIPodStatusWithReasonCache(t *testing.T) {
 				}},
 			},
 		},
+		// For Unknown Container Status:
+		// * In certain situations a container can be running and fail to retrieve the status which results in
+		// * a transition to the Unknown state. Prior to this fix, a container would make an invalid transition
+		// * from Running->Waiting. This test validates the correct behavior of transitioning from Running->Terminated.
+		{
+			containers: []v1.Container{{Name: "unknown"}},
+			statuses: []*kubecontainer.Status{
+				{
+					Name:  "unknown",
+					State: kubecontainer.ContainerStateUnknown,
+				},
+				{
+					Name:  "unknown",
+					State: kubecontainer.ContainerStateRunning,
+				},
+			},
+			reasons: map[string]error{},
+			oldStatuses: []v1.ContainerStatus{{
+				Name:  "unknown",
+				State: v1.ContainerState{Running: &v1.ContainerStateRunning{}},
+			}},
+			expectedState: map[string]v1.ContainerState{
+				"unknown": {Terminated: &v1.ContainerStateTerminated{
+					ExitCode: 137,
+					Message:  "The container could not be located when the pod was terminated",
+					Reason:   "ContainerStatusUnknown",
+				}},
+			},
+			expectedLastTerminationState: map[string]v1.ContainerState{
+				"unknown": {Running: &v1.ContainerStateRunning{}},
+			},
+		},
 	}
 
 	for i, test := range tests {