Add support for basic cgroup management

pkg/kubelet/cm/cgroup_manager_linux.go

@@ -0,0 +1,113 @@
+/*
+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"
+
+	libcontainerconfigs "github.com/opencontainers/runc/libcontainer/configs"
+)
+
+// cgroupManagerImpl implements the CgroupManager interface.
+// Its a stateless object which can be used to
+// update,create or delete any number of cgroups
+// It uses the Libcontainer raw fs cgroup manager for cgroup management.
+type cgroupManagerImpl struct {
+	// subsystems holds information about all the
+	// mounted cgroup subsytems on the node
+	subsystems *cgroupSubsystems
+}
+
+// Make sure that cgroupManagerImpl implements the CgroupManager interface
+var _ CgroupManager = &cgroupManagerImpl{}
+
+// NewCgroupManager is a factory method that returns a CgroupManager
+func NewCgroupManager(cs *cgroupSubsystems) CgroupManager {
+	return &cgroupManagerImpl{
+		subsystems: cs,
+	}
+}
+
+// Destroy destroys the specified cgroup
+func (m *cgroupManagerImpl) Destroy(cgroupConfig *CgroupConfig) error {
+	//cgroup name
+	name := cgroupConfig.Name
+
+	// get the fscgroup Manager with the specified cgroup configuration
+	fsCgroupManager, err := getLibcontainerCgroupManager(cgroupConfig, m.subsystems)
+
+	if err != nil {
+		return fmt.Errorf("Unable to destroy cgroup paths for cgroup %v : %v", name, err)
+	}
+	// Delete cgroups using libcontainers Managers Destroy() method
+	if err := fsCgroupManager.Destroy(); err != nil {
+		return fmt.Errorf("Unable to destroy cgroup paths for cgroup %v : %v", name, err)
+	}
+	return nil
+}
+
+// Update updates the cgroup with the specified Cgroup Configuration
+func (m *cgroupManagerImpl) Update(cgroupConfig *CgroupConfig) error {
+	//cgroup name
+	name := cgroupConfig.Name
+
+	// get the fscgroup Manager with the specified cgroup configuration
+	fsCgroupManager, err := getLibcontainerCgroupManager(cgroupConfig, m.subsystems)
+	if err != nil {
+		return fmt.Errorf("Failed to update cgroup for %v : %v", name, err)
+	}
+	// get config object for passing to Set()
+	config := &libcontainerconfigs.Config{
+		Cgroups: fsCgroupManager.Cgroups,
+	}
+
+	// Update cgroup configuration using libcontainers Managers Set() method
+	if err := fsCgroupManager.Set(config); err != nil {
+		return fmt.Errorf("Failed to update cgroup for %v: %v", name, err)
+	}
+	return nil
+}
+
+// Create creates the specified cgroup
+func (m *cgroupManagerImpl) Create(cgroupConfig *CgroupConfig) error {
+	//cgroup name
+	name := cgroupConfig.Name
+
+	// get the fscgroup Manager with the specified cgroup configuration
+	fsCgroupManager, err := getLibcontainerCgroupManager(cgroupConfig, m.subsystems)
+	if err != nil {
+		return fmt.Errorf("Failed to create cgroup for %v : %v", name, err)
+	}
+	// get config object for passing to libcontainer's Set() method
+	config := &libcontainerconfigs.Config{
+		Cgroups: fsCgroupManager.Cgroups,
+	}
+	//Apply(0) is a hack to create the cgroup directories for each resource
+	// subsystem. The function [cgroups.Manager.apply()] applies cgroup
+	// configuration to the process with the specified pid.
+	// It creates cgroup files for each subsytems and writes the pid
+	// in the tasks file. We use the function to create all the required
+	// cgroup files but not attach any "real" pid to the cgroup.
+	if err := fsCgroupManager.Apply(0); err != nil {
+		return fmt.Errorf("Failed to create cgroup for %v: %v", name, err)
+	}
+	// Update cgroup configuration using libcontainers Managers Set() method
+	if err := fsCgroupManager.Set(config); err != nil {
+		return fmt.Errorf("Failed to create cgroup for %v: %v", name, err)
+	}
+	return nil
+}