【kubernetes/k8s源码分析】 rook operator agent源码分析

启动命令

    rook ceph agent

启动默认参数

    --help=false, --log-flush-frequency=5s, --log-level=INFO

    挂载路经：/usr/libexec/kubernetes/kubelet-plugins/volume/exec

每个 k8s node 中都启动 rook agent，接受 rook operator 管理，每个agent都配置一个Flexvolume插件，该插件与Kubernetes的卷控制器框架集成在一起。处理节点上所需的所有存储操作，例如附加网络存储设备，安装卷和格式化文件系统

所有代码一个模式，直接分析startAgent函数

 

1. 创建客户端，创建上下文

clientset, apiExtClientset, rookClientset, err := rook.GetClientset()
if err != nil {
	rook.TerminateFatal(fmt.Errorf("failed to get k8s client. %+v", err))
}

logger.Infof("starting rook ceph agent")
context := &clusterd.Context{
	Executor:              &exec.CommandExecutor{},
	ConfigDir:             k8sutil.DataDir,
	NetworkInfo:           clusterd.NetworkInfo{},
	Clientset:             clientset,
	APIExtensionClientset: apiExtClientset,
	RookClientset:         rookClientset,
}

  1.1 attachement.New

    创建CRD controller管理CRD资源，实现了Attachment接口

• Create(volumeAttachment *rookalpha.Volume) error
• Get(namespace, name string) (*rookalpha.Volume, error)
• List(namespace string) (*rookalpha.VolumeList, error) Update(volumeAttachment *rookalpha.Volume) error
• Delete(namespace, name string) error

volumeAttachmentController, err := attachment.New(a.context)
if err != nil {
	return fmt.Errorf("failed to create volume attachment controller: %+v", err)
}

  1.2 NewVolumeManager

    NewVolumeManager对于ceph卷创建attacher

// NewVolumeManager create attacher for ceph volumes
func NewVolumeManager(context *clusterd.Context) (*VolumeManager, error) {
	vm := &VolumeManager{
		context:          context,
		devicePathFinder: &devicePathFinder{},
	}
	err := vm.Init()
	return vm, err
}

    1.2.1 Init函数

     使用系统调用cat /lib/modules/3.10.0-957.el7.x86_64/modules.builtin | grep rbd，rbd没有加载内和模块

// check if the rbd is a builtin kernel module, if it is then we don't need to load it manually
in, err := sys.IsBuiltinKernelModule(rbdKernelModuleName, vm.context.Executor)
if err != nil {
	return err
}
if in == true {
	logger.Noticef("volume manager is a builtin kernel module, don't load it manually")
	return nil
}

   1.2.2 执行系统调用命令 modinfo -F parm rbd

    # modinfo -F parm rbd
       single_major:Use a single major number for all rbd devices (default: true) (bool)

func CheckKernelModuleParam(name, param string, executor pkgexec.Executor) (bool, error) {
	out, err := executor.ExecuteCommandWithOutput(false, "check kmod param", "modinfo", "-F", "parm", name)
	if err != nil {
		return false, fmt.Errorf("failed to check for %s module %s param: %+v", name, param, err)
	}

	result := Grep(out, fmt.Sprintf("^%s", param))
	return result != "", nil
}

   1.2.3 执行系统调用命令 odprobe rbd single_major=Y 

func LoadKernelModule(name string, options []string, executor pkgexec.Executor) error {
	if options == nil {
		options = []string{}
	}

	args := append([]string{name}, options...)

	if err := executor.ExecuteCommand(false, fmt.Sprintf("modprobe %s", name), "modprobe", args[:]...); err != nil {
		return fmt.Errorf("failed to load kernel module %s: %+v", name, err)
	}

	return nil
}

 

2. 创建controller来处理flexvolume driver的事件

     Controller实现了 Attach Detach方法，FlexvolumeServer 包裹了 Controller

flexvolumeController := flexvolume.NewController(a.context, volumeAttachmentController, volumeManager, mountSecurityMode)

flexvolumeServer := flexvolume.NewFlexvolumeServer(
	a.context,
	flexvolumeController,
)

 

3. FlexvolumeServer Start函数

    注册rook，rook-ceph的driver name，监听socker与driver通信，路径为/flexmnt，宿主机路径/usr/libexec/kubernetes/kubelet-plugins/volume/exec 

    创建 socket

flexDriverVendors := []string{flexvolume.FlexvolumeVendor, flexvolume.FlexvolumeVendorLegacy}
for i, vendor := range flexDriverVendors {
	if i > 0 {
		// Wait before the next driver is registered. In 1.11 and newer there is a timing issue if flex drivers are registered too quickly.
		// See https://github.com/rook/rook/issues/1501 and https://github.com/kubernetes/kubernetes/issues/60694
		time.Sleep(time.Second)
	}

	err = flexvolumeServer.Start(vendor, driverName)
	if err != nil {
		return fmt.Errorf("failed to start flex volume server %s/%s, %+v", vendor, driverName, err)
	}

	// Wait before the next driver is registered
	time.Sleep(time.Second)

	// Register drivers both with the name of the namespace and the name "rook"
	// for the volume plugins not based on the namespace.
	err = flexvolumeServer.Start(vendor, flexvolume.FlexDriverName)
	if err != nil {
		return fmt.Errorf("failed to start flex volume server %s/%s. %+v", vendor, flexvolume.FlexDriverName, err)
	}
}

  

4. NewClusterController函数

    创建一个controller实例，watch集群事件，rook-ceph名下的CephCluster资源

// NewClusterController creates a new instance of a ClusterController
func NewClusterController(context *clusterd.Context, flexvolumeController flexvolume.VolumeController,
	volumeAttachment attachment.Attachment) *ClusterController {

	return &ClusterController{
		context:              context,
		volumeAttachment:     volumeAttachment,
		flexvolumeController: flexvolumeController,
	}
}