dockershim: don't spam logs with pod IP errors before networking is ready

GenericPLEG's 1s relist() loop races against pod network setup.  It
may be called after the infra container has started but before
network setup is done, since PLEG and the runtime's SyncPod() run
in different goroutines.

Track network setup status and don't bother trying to read the pod's
IP address if networking is not yet ready.

See also: https://bugzilla.redhat.com/show_bug.cgi?id=1434950

Mar 22 12:18:17 ip-172-31-43-89 atomic-openshift-node: E0322
   12:18:17.651013   25624 docker_manager.go:378] NetworkPlugin
   cni failed on the status hook for pod 'pausepods22' - Unexpected
   command output Device "eth0" does not exist.

pkg/kubelet/dockershim/docker_sandbox_test.go

@@ -133,6 +133,8 @@ func TestSandboxStatus(t *testing.T) {
 	expected.State = runtimeapi.PodSandboxState_SANDBOX_NOTREADY
 	err = ds.StopPodSandbox(id)
 	assert.NoError(t, err)
+	// IP not valid after sandbox stop
+	expected.Network.Ip = ""
 	status, err = ds.PodSandboxStatus(id)
 	assert.Equal(t, expected, status)
 
@@ -143,6 +145,49 @@ func TestSandboxStatus(t *testing.T) {
 	assert.Error(t, err, fmt.Sprintf("status of sandbox: %+v", status))
 }
 
+// TestSandboxStatusAfterRestart tests that retrieving sandbox status returns
+// an IP address even if RunPodSandbox() was not yet called for this pod, as
+// would happen on kubelet restart
+func TestSandboxStatusAfterRestart(t *testing.T) {
+	ds, _, fClock := newTestDockerService()
+	config := makeSandboxConfig("foo", "bar", "1", 0)
+
+	// TODO: The following variables depend on the internal
+	// implementation of FakeDockerClient, and should be fixed.
+	fakeIP := "2.3.4.5"
+
+	state := runtimeapi.PodSandboxState_SANDBOX_READY
+	ct := int64(0)
+	hostNetwork := false
+	expected := &runtimeapi.PodSandboxStatus{
+		State:       state,
+		CreatedAt:   ct,
+		Metadata:    config.Metadata,
+		Network:     &runtimeapi.PodSandboxNetworkStatus{Ip: fakeIP},
+		Linux:       &runtimeapi.LinuxPodSandboxStatus{Namespaces: &runtimeapi.Namespace{Options: &runtimeapi.NamespaceOption{HostNetwork: hostNetwork}}},
+		Labels:      map[string]string{},
+		Annotations: map[string]string{},
+	}
+
+	// Create the sandbox.
+	fClock.SetTime(time.Now())
+	expected.CreatedAt = fClock.Now().UnixNano()
+
+	createConfig, err := ds.makeSandboxDockerConfig(config, defaultSandboxImage)
+	assert.NoError(t, err)
+
+	createResp, err := ds.client.CreateContainer(*createConfig)
+	assert.NoError(t, err)
+	err = ds.client.StartContainer(createResp.ID)
+	assert.NoError(t, err)
+
+	// Check status without RunPodSandbox() having set up networking
+	expected.Id = createResp.ID // ID is only known after the creation.
+	status, err := ds.PodSandboxStatus(createResp.ID)
+	assert.NoError(t, err)
+	assert.Equal(t, expected, status)
+}
+
 // TestNetworkPluginInvocation checks that the right SetUpPod and TearDownPod
 // calls are made when we run/stop a sandbox.
 func TestNetworkPluginInvocation(t *testing.T) {