Merge pull request kubernetes#18425 from dcbw/kube-59301-backport

Automatic merge from submit-queue.

UPSTREAM: 59301: dockershim: don't check pod IP in StopPodSandbox

We're about to tear the container down, there's no point.  It also suppresses
an annoying error message due to kubelet stupidity that causes multiple
parallel calls to StopPodSandbox for the same sandbox.

docker_sandbox.go:355] failed to read pod IP from plugin/docker: NetworkPlugin cni failed on the status hook for pod "docker-registry-1-deploy_default": Unexpected command output nsenter: cannot open /proc/22646/ns/net: No such file or directory

1) A first StopPodSandbox() request triggered by SyncLoop(PLEG) for
a ContainerDied event calls into TearDownPod() and thus the network
plugin.  Until this completes, networkReady=true for the
sandbox.

2) A second StopPodSandbox() request triggered by SyncLoop(REMOVE)
calls PodSandboxStatus() and calls into the network plugin to read
the IP address because networkReady=true

3) The first request exits the network plugin, sets networReady=false,
and calls StopContainer() on the sandbox.  This destroys the network
namespace.

4) The second request finally gets around to running nsenter but
the network namespace is already destroyed.  It returns an error
which is logged by getIP().

Fixes: openshift/origin#18414

@danwinship

Origin-commit: 73e9c8fa185d0f7bb9a0798185f78598cf4bb42b

pkg/kubelet/dockershim/docker_sandbox.go

@@ -174,19 +174,15 @@ func (ds *dockerService) RunPodSandbox(config *runtimeapi.PodSandboxConfig) (id
 func (ds *dockerService) StopPodSandbox(podSandboxID string) error {
 	var namespace, name string
 	var hostNetwork bool
-	var checkpointErr, statusErr error
 
-	// Try to retrieve sandbox information from docker daemon or sandbox checkpoint
-	status, statusErr := ds.PodSandboxStatus(podSandboxID)
+	// Try to retrieve minimal sandbox information from docker daemon or sandbox checkpoint.
+	inspectResult, metadata, statusErr := ds.getPodSandboxDetails(podSandboxID)
 	if statusErr == nil {
-		nsOpts := status.GetLinux().GetNamespaces().GetOptions()
-		hostNetwork = nsOpts != nil && nsOpts.HostNetwork
-		m := status.GetMetadata()
-		namespace = m.Namespace
-		name = m.Name
+		namespace = metadata.Namespace
+		name = metadata.Name
+		hostNetwork = sharesHostNetwork(inspectResult)
 	} else {
-		var checkpoint *PodSandboxCheckpoint
-		checkpoint, checkpointErr = ds.checkpointHandler.GetCheckpoint(podSandboxID)
+		checkpoint, checkpointErr := ds.checkpointHandler.GetCheckpoint(podSandboxID)
 
 		// Proceed if both sandbox container and checkpoint could not be found. This means that following
 		// actions will only have sandbox ID and not have pod namespace and name information.
@@ -341,10 +337,25 @@ func (ds *dockerService) getIP(podSandboxID string, sandbox *dockertypes.Contain
 	return ""
 }
 
+// Returns the inspect container response, the sandbox metadata, and network namespace mode
+func (ds *dockerService) getPodSandboxDetails(podSandboxID string) (*dockertypes.ContainerJSON, *runtimeapi.PodSandboxMetadata, error) {
+	resp, err := ds.client.InspectContainer(podSandboxID)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	metadata, err := parseSandboxName(resp.Name)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return resp, metadata, nil
+}
+
 // PodSandboxStatus returns the status of the PodSandbox.
 func (ds *dockerService) PodSandboxStatus(podSandboxID string) (*runtimeapi.PodSandboxStatus, error) {
 	// Inspect the container.
-	r, err := ds.client.InspectContainer(podSandboxID)
+	r, metadata, err := ds.getPodSandboxDetails(podSandboxID)
 	if err != nil {
 		return nil, err
 	}
@@ -370,10 +381,6 @@ func (ds *dockerService) PodSandboxStatus(podSandboxID string) (*runtimeapi.PodS
 	}
 	hostNetwork := sharesHostNetwork(r)
 
-	metadata, err := parseSandboxName(r.Name)
-	if err != nil {
-		return nil, err
-	}
 	labels, annotations := extractLabels(r.Config.Labels)
 	return &runtimeapi.PodSandboxStatus{
 		Id:          r.ID,

pkg/kubelet/dockershim/docker_sandbox_test.go

@@ -207,9 +207,6 @@ func TestNetworkPluginInvocation(t *testing.T) {
 
 	mockPlugin.EXPECT().Name().Return("mockNetworkPlugin").AnyTimes()
 	setup := mockPlugin.EXPECT().SetUpPod(ns, name, cID)
-	// StopPodSandbox performs a lookup on status to figure out if the sandbox
-	// is running with hostnetworking, as all its given is the ID.
-	mockPlugin.EXPECT().GetPodNetworkStatus(ns, name, cID)
 	mockPlugin.EXPECT().TearDownPod(ns, name, cID).After(setup)
 
 	_, err := ds.RunPodSandbox(c)