kubelet: cm: refactor QoS logic into seperate interface

pkg/kubelet/cm/qos_container_manager_linux.go

@@ -0,0 +1,137 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+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"
+	"sync"
+
+	"k8s.io/kubernetes/pkg/api/v1"
+)
+
+type QOSContainerManager interface {
+	Start(*v1.Node, ActivePodsFunc) error
+	GetQOSContainersInfo() QOSContainersInfo
+	UpdateCgroups() error
+}
+
+type qosContainerManagerImpl struct {
+	sync.Mutex
+	nodeInfo          *v1.Node
+	qosContainersInfo QOSContainersInfo
+	subsystems        *CgroupSubsystems
+	cgroupManager     CgroupManager
+	activePods        ActivePodsFunc
+	cgroupRoot        string
+}
+
+func NewQOSContainerManager(subsystems *CgroupSubsystems, cgroupRoot string, nodeConfig NodeConfig) (QOSContainerManager, error) {
+	if !nodeConfig.CgroupsPerQOS {
+		return &qosContainerManagerNoop{
+			cgroupRoot: CgroupName(nodeConfig.CgroupRoot),
+		}, nil
+	}
+
+	return &qosContainerManagerImpl{
+		subsystems:    subsystems,
+		cgroupManager: NewCgroupManager(subsystems, nodeConfig.CgroupDriver),
+		cgroupRoot:    cgroupRoot,
+	}, nil
+}
+
+func (m *qosContainerManagerImpl) GetQOSContainersInfo() QOSContainersInfo {
+	return m.qosContainersInfo
+}
+
+func (m *qosContainerManagerImpl) Start(nodeInfo *v1.Node, activePods ActivePodsFunc) error {
+	cm := m.cgroupManager
+	rootContainer := m.cgroupRoot
+	if !cm.Exists(CgroupName(rootContainer)) {
+		return fmt.Errorf("root container %s doesn't exist", rootContainer)
+	}
+
+	// Top level for Qos containers are created only for Burstable
+	// and Best Effort classes
+	qosClasses := [2]v1.PodQOSClass{v1.PodQOSBurstable, v1.PodQOSBestEffort}
+
+	// Create containers for both qos classes
+	for _, qosClass := range qosClasses {
+		// get the container's absolute name
+		absoluteContainerName := CgroupName(path.Join(rootContainer, string(qosClass)))
+
+		resourceParameters := &ResourceConfig{}
+		// the BestEffort QoS class has a statically configured minShares value
+		if qosClass == v1.PodQOSBestEffort {
+			minShares := int64(MinShares)
+			resourceParameters.CpuShares = &minShares
+		}
+		// containerConfig object stores the cgroup specifications
+		containerConfig := &CgroupConfig{
+			Name:               absoluteContainerName,
+			ResourceParameters: resourceParameters,
+		}
+		// check if it exists
+		if !cm.Exists(absoluteContainerName) {
+			if err := cm.Create(containerConfig); err != nil {
+				return fmt.Errorf("failed to create top level %v QOS cgroup : %v", qosClass, err)
+			}
+		} else {
+			// to ensure we actually have the right state, we update the config on startup
+			if err := cm.Update(containerConfig); err != nil {
+				return fmt.Errorf("failed to update top level %v QOS cgroup : %v", qosClass, err)
+			}
+		}
+	}
+	// Store the top level qos container names
+	m.qosContainersInfo = QOSContainersInfo{
+		Guaranteed: rootContainer,
+		Burstable:  path.Join(rootContainer, string(v1.PodQOSBurstable)),
+		BestEffort: path.Join(rootContainer, string(v1.PodQOSBestEffort)),
+	}
+	m.nodeInfo = nodeInfo
+	m.activePods = activePods
+
+	return nil
+}
+
+func (m *qosContainerManagerImpl) UpdateCgroups() error {
+	m.Lock()
+	defer m.Unlock()
+
+	// TODO: Update cgroups
+
+	return nil
+}
+
+type qosContainerManagerNoop struct {
+	cgroupRoot CgroupName
+}
+
+var _ QOSContainerManager = &qosContainerManagerNoop{}
+
+func (m *qosContainerManagerNoop) GetQOSContainersInfo() QOSContainersInfo {
+	return QOSContainersInfo{}
+}
+
+func (m *qosContainerManagerNoop) Start(_ *v1.Node, _ ActivePodsFunc) error {
+	return nil
+}
+
+func (m *qosContainerManagerNoop) UpdateCgroups() error {
+	return nil
+}