Device plugin code refactoring to cope with file move.

While moving device_plugin_handler_test.go from pkg/kubelet/cm/ to
pkg/kubelet/cm/deviceplugin/, we can no longer uses cm in its tests
because that would cause a cycle dependency. To solve this problem,
I moved the main cm GetResources functionality as well as part of the
current device plugin handler Allocate functionality into a new device
plugin handler function, GetDeviceRunContainerOptions(). This
refactoring is also needed by another PR 51895 that moves device
allocation into admission phase. Now device plugin handler Allocate()
first checks whether there is cached device runtime state and only
issues Allocate grpc call if there is no cached state available.
The new GetDeviceRunContainerOptions() function simply returns device
runtime config from the cached state. To support this change, extended the
podDevices struct and checkpoint data structure with device runtime state.

pkg/kubelet/cm/container_manager_linux.go

@@ -45,6 +45,7 @@ import (
 	internalapi "k8s.io/kubernetes/pkg/kubelet/apis/cri"
 	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
 	"k8s.io/kubernetes/pkg/kubelet/cm/cpumanager"
+	"k8s.io/kubernetes/pkg/kubelet/cm/deviceplugin"
 	cmutil "k8s.io/kubernetes/pkg/kubelet/cm/util"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/qos"
@@ -125,7 +126,7 @@ type containerManagerImpl struct {
 	// Interface for QoS cgroup management
 	qosContainerManager QOSContainerManager
 	// Interface for exporting and allocating devices reported by device plugins.
-	devicePluginHandler DevicePluginHandler
+	devicePluginHandler deviceplugin.Handler
 	// Interface for CPU affinity management.
 	cpuManager cpumanager.Manager
 }
@@ -273,9 +274,9 @@ func NewContainerManager(mountUtil mount.Interface, cadvisorInterface cadvisor.I
 
 	glog.Infof("Creating device plugin handler: %t", devicePluginEnabled)
 	if devicePluginEnabled {
-		cm.devicePluginHandler, err = NewDevicePluginHandlerImpl(updateDeviceCapacityFunc)
+		cm.devicePluginHandler, err = deviceplugin.NewHandlerImpl(updateDeviceCapacityFunc)
 	} else {
-		cm.devicePluginHandler, err = NewDevicePluginHandlerStub()
+		cm.devicePluginHandler, err = deviceplugin.NewHandlerStub()
 	}
 	if err != nil {
 		return nil, err
@@ -618,72 +619,17 @@ func (cm *containerManagerImpl) GetResources(pod *v1.Pod, container *v1.Containe
 	opts := &kubecontainer.RunContainerOptions{}
 	// Gets devices, mounts, and envs from device plugin handler.
 	glog.V(3).Infof("Calling devicePluginHandler AllocateDevices")
-	// Maps to detect duplicate settings.
-	devsMap := make(map[string]string)
-	mountsMap := make(map[string]string)
-	envsMap := make(map[string]string)
-	allocResps, err := cm.devicePluginHandler.Allocate(pod, container, activePods)
+	err := cm.devicePluginHandler.Allocate(pod, container, activePods)
 	if err != nil {
 		return opts, err
 	}
-	// Loops through AllocationResponses of all required extended resources.
-	for _, resp := range allocResps {
-		// Each Allocate response has the following artifacts.
-		// Environment variables
-		// Mount points
-		// Device files
-		// These artifacts are per resource per container.
-		// Updates RunContainerOptions.Envs.
-		for k, v := range resp.Envs {
-			if e, ok := envsMap[k]; ok {
-				glog.V(3).Infof("skip existing envs %s %s", k, v)
-				if e != v {
-					glog.Errorf("Environment variable %s has conflicting setting: %s and %s", k, e, v)
-				}
-				continue
-			}
-			envsMap[k] = v
-			opts.Envs = append(opts.Envs, kubecontainer.EnvVar{Name: k, Value: v})
-		}
-
-		// Updates RunContainerOptions.Devices.
-		for _, dev := range resp.Devices {
-			if d, ok := devsMap[dev.ContainerPath]; ok {
-				glog.V(3).Infof("skip existing device %s %s", dev.ContainerPath, dev.HostPath)
-				if d != dev.HostPath {
-					glog.Errorf("Container device %s has conflicting mapping host devices: %s and %s",
-						dev.ContainerPath, d, dev.HostPath)
-				}
-				continue
-			}
-			devsMap[dev.ContainerPath] = dev.HostPath
-			opts.Devices = append(opts.Devices, kubecontainer.DeviceInfo{
-				PathOnHost:      dev.HostPath,
-				PathInContainer: dev.ContainerPath,
-				Permissions:     dev.Permissions,
-			})
-		}
-		// Updates RunContainerOptions.Mounts.
-		for _, mount := range resp.Mounts {
-			if m, ok := mountsMap[mount.ContainerPath]; ok {
-				glog.V(3).Infof("skip existing mount %s %s", mount.ContainerPath, mount.HostPath)
-				if m != mount.HostPath {
-					glog.Errorf("Container mount %s has conflicting mapping host mounts: %s and %s",
-						mount.ContainerPath, m, mount.HostPath)
-				}
-				continue
-			}
-			mountsMap[mount.ContainerPath] = mount.HostPath
-			opts.Mounts = append(opts.Mounts, kubecontainer.Mount{
-				Name:          mount.ContainerPath,
-				ContainerPath: mount.ContainerPath,
-				HostPath:      mount.HostPath,
-				ReadOnly:      mount.ReadOnly,
-				// TODO: This may need to be part of Device plugin API.
-				SELinuxRelabel: false,
-			})
-		}
+	devOpts := cm.devicePluginHandler.GetDeviceRunContainerOptions(pod, container)
+	if devOpts == nil {
+		return opts, nil
 	}
+	opts.Devices = append(opts.Devices, devOpts.Devices...)
+	opts.Mounts = append(opts.Mounts, devOpts.Mounts...)
+	opts.Envs = append(opts.Envs, devOpts.Envs...)
 	return opts, nil
 }