Add support for basic cgroup management

pkg/kubelet/cm/helpers_linux.go

@@ -0,0 +1,98 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cm
+
+import (
+	"fmt"
+	"path"
+
+	libcontainercgroups "github.com/opencontainers/runc/libcontainer/cgroups"
+	cgroupfs "github.com/opencontainers/runc/libcontainer/cgroups/fs"
+	libcontainerconfigs "github.com/opencontainers/runc/libcontainer/configs"
+)
+
+// cgroupSubsystems holds information about the mounted cgroup subsytems
+type cgroupSubsystems struct {
+	// Cgroup subsystem mounts.
+	// e.g.: "/sys/fs/cgroup/cpu" -> ["cpu", "cpuacct"]
+	mounts []libcontainercgroups.Mount
+
+	// Cgroup subsystem to their mount location.
+	// e.g.: "cpu" -> "/sys/fs/cgroup/cpu"
+	mountPoints map[string]string
+}
+
+// GetCgroupSubsystems returns information about the mounted cgroup subsystems
+func getCgroupSubsystems() (*cgroupSubsystems, error) {
+	// Get all cgroup mounts.
+	allCgroups, err := libcontainercgroups.GetCgroupMounts()
+	if err != nil {
+		return &cgroupSubsystems{}, err
+	}
+	if len(allCgroups) == 0 {
+		return &cgroupSubsystems{}, fmt.Errorf("failed to find cgroup mounts")
+	}
+
+	//TODO(@dubstack) should we trim to only the supported ones
+	mountPoints := make(map[string]string, len(allCgroups))
+	for _, mount := range allCgroups {
+		for _, subsystem := range mount.Subsystems {
+			mountPoints[subsystem] = mount.Mountpoint
+		}
+	}
+	return &cgroupSubsystems{
+		mounts:      allCgroups,
+		mountPoints: mountPoints,
+	}, nil
+}
+
+// getLibcontainerCgroupManager returns libcontainer's cgroups manager
+// object with the specified cgroup configuration
+func getLibcontainerCgroupManager(cgroupConfig *CgroupConfig, subsystems *cgroupSubsystems) (*cgroupfs.Manager, error) {
+	// get cgroup name
+	name := cgroupConfig.Name
+
+	// Get map of all cgroup paths on the system for the particular cgroup
+	cgroupPaths := make(map[string]string, len(subsystems.mountPoints))
+	for key, val := range subsystems.mountPoints {
+		cgroupPaths[key] = path.Join(val, name)
+	}
+
+	// Extract the cgroup resource parameters
+	resourceConfig := cgroupConfig.ResourceParameters
+	resources := &libcontainerconfigs.Resources{}
+	resources.AllowAllDevices = true
+	if resourceConfig.Memory != nil {
+		resources.Memory = *resourceConfig.Memory
+	}
+	if resourceConfig.CpuShares != nil {
+		resources.CpuShares = *resourceConfig.CpuShares
+	}
+	if resourceConfig.CpuQuota != nil {
+		resources.CpuQuota = *resourceConfig.CpuQuota
+	}
+	// Initialize libcontainer's cgroup config
+	libcontainerCgroupConfig := &libcontainerconfigs.Cgroup{
+		Name:      path.Base(name),
+		Parent:    path.Dir(name),
+		Resources: resources,
+	}
+	return &cgroupfs.Manager{
+		Cgroups: libcontainerCgroupConfig,
+		Paths:   cgroupPaths,
+	}, nil
+}