kubelet源码阅读（三）——kubelet调用device plugin的allocate接口

kubernetes-master/pkg/kubelet/cm/devicemanager/endpoint.go

入参：

　　devs是设备ID

响应：

　　AllocateResponse包含了需要注入到容器中的工作件（envs环境变量、mounts挂在信息、devices设备信息、annotations注解信息、cdidevice名称），以便容器能访问到AllocateRequest中deviceIDs。

　　返回的信息中可以选择使用某一种方式，例如：只返回env，就是为容器添加环境变量。nvidia/k8s-device-plugin使用为容器添加环境变量NVIDIA_VISIBLE_DEVICES的方式，支持容器使用GPU卡。nvidia也支持了使用cdi的方式。这需要container的版本支持cdi。

失败处理：

　　如果kubelet发送了对dev1和dev2的分配请求。dev1 的分配成功，但 dev2 的分配失败。设备插件应发送 ListAndWatch 更新并使分配请求失败。

// allocate issues Allocate gRPC call to the device plugin.
func (e *endpointImpl) allocate(devs []string) (*pluginapi.AllocateResponse, error) {
    if e.isStopped() {
        return nil, fmt.Errorf(errEndpointStopped, e)
    }
    return e.api.Allocate(context.Background(), &pluginapi.AllocateRequest{
        ContainerRequests: []*pluginapi.ContainerAllocateRequest{
            {DevicesIDs: devs},
        },
    })
}

 

// AllocateResponse includes the artifacts that needs to be injected into
// a container for accessing 'deviceIDs' that were mentioned as part of
// 'AllocateRequest'.
// Failure Handling:
// if Kubelet sends an allocation request for dev1 and dev2.
// Allocation on dev1 succeeds but allocation on dev2 fails.
// The Device plugin should send a ListAndWatch update and fail the
// Allocation request
type AllocateResponse struct {
    ContainerResponses   []*ContainerAllocateResponse `protobuf:"bytes,1,rep,name=container_responses,json=containerResponses,proto3" json:"container_responses,omitempty"`
    XXX_NoUnkeyedLiteral struct{}                     `json:"-"`
    XXX_sizecache        int32                        `json:"-"`
}


type ContainerAllocateResponse struct {
    // List of environment variable to be set in the container to access one of more devices.
    Envs map[string]string `protobuf:"bytes,1,rep,name=envs,proto3" json:"envs,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
    // Mounts for the container.
    Mounts []*Mount `protobuf:"bytes,2,rep,name=mounts,proto3" json:"mounts,omitempty"`
    // Devices for the container.
    Devices []*DeviceSpec `protobuf:"bytes,3,rep,name=devices,proto3" json:"devices,omitempty"`
    // Container annotations to pass to the container runtime
    Annotations map[string]string `protobuf:"bytes,4,rep,name=annotations,proto3" json:"annotations,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
    // CDI devices for the container.
    CDIDevices           []*CDIDevice `protobuf:"bytes,5,rep,name=cdi_devices,json=cdiDevices,proto3" json:"cdi_devices,omitempty"`
    XXX_NoUnkeyedLiteral struct{}     `json:"-"`
    XXX_sizecache        int32        `json:"-"`
}