only collect metrics for cgroups required by the summary API

pkg/kubelet/cm/helpers_linux.go

@@ -236,3 +236,37 @@ func getCgroupProcs(dir string) ([]int, error) {
 func GetPodCgroupNameSuffix(podUID types.UID) string {
 	return podCgroupNamePrefix + string(podUID)
 }
+
+// NodeAllocatableRoot returns the literal cgroup path for the node allocatable cgroup
+func NodeAllocatableRoot(cgroupRoot, cgroupDriver string) string {
+	root := ParseCgroupfsToCgroupName(cgroupRoot)
+	nodeAllocatableRoot := NewCgroupName(root, defaultNodeAllocatableCgroupName)
+	if libcontainerCgroupManagerType(cgroupDriver) == libcontainerSystemd {
+		return nodeAllocatableRoot.ToSystemd()
+	}
+	return nodeAllocatableRoot.ToCgroupfs()
+}
+
+// GetKubeletContainer returns the cgroup the kubelet will use
+func GetKubeletContainer(kubeletCgroups string) (string, error) {
+	if kubeletCgroups == "" {
+		cont, err := getContainer(os.Getpid())
+		if err != nil {
+			return "", err
+		}
+		return cont, nil
+	}
+	return kubeletCgroups, nil
+}
+
+// GetRuntimeContainer returns the cgroup used by the container runtime
+func GetRuntimeContainer(containerRuntime, runtimeCgroups string) (string, error) {
+	if containerRuntime == "docker" {
+		cont, err := getContainerNameForProcess(dockerProcessName, dockerPidFile)
+		if err != nil {
+			return "", fmt.Errorf("failed to get container name for docker process: %v", err)
+		}
+		return cont, nil
+	}
+	return runtimeCgroups, nil
+}