kubelet: reduce extraneous logging for pods using host network

pkg/kubelet/dockershim/docker_sandbox.go

@@ -178,9 +178,6 @@ func (ds *dockerService) getIPFromPlugin(sandbox *dockertypes.ContainerJSON) (st
 		return "", err
 	}
 	msg := fmt.Sprintf("Couldn't find network status for %s/%s through plugin", metadata.Namespace, metadata.Name)
-	if sharesHostNetwork(sandbox) {
-		return "", fmt.Errorf("%v: not responsible for host-network sandboxes", msg)
-	}
 	cID := kubecontainer.BuildContainerID(runtimeName, sandbox.ID)
 	networkStatus, err := ds.networkPlugin.GetPodNetworkStatus(metadata.Namespace, metadata.Name, cID)
 	if err != nil {
@@ -202,6 +199,11 @@ func (ds *dockerService) getIP(sandbox *dockertypes.ContainerJSON) (string, erro
 	if sandbox.NetworkSettings == nil {
 		return "", nil
 	}
+	if sharesHostNetwork(sandbox) {
+		// For sandboxes using host network, the shim is not responsible for
+		// reporting the IP.
+		return "", nil
+	}
 	if IP, err := ds.getIPFromPlugin(sandbox); err != nil {
 		glog.Warningf("%v", err)
 	} else if IP != "" {

pkg/kubelet/kuberuntime/kuberuntime_sandbox.go

@@ -198,7 +198,9 @@ func (m *kubeGenericRuntimeManager) determinePodSandboxIP(podNamespace, podName
 		return ""
 	}
 	ip := podSandbox.Network.Ip
-	if net.ParseIP(ip) == nil {
+	if len(ip) != 0 && net.ParseIP(ip) == nil {
+		// ip could be an empty string if runtime is not responsible for the
+		// IP (e.g., host networking).
 		glog.Warningf("Pod Sandbox reported an unparseable IP %v", ip)
 		return ""
 	}