external-provisioner源码分析（3）-组件启动参数分析

更多ceph-csi其他源码分析，请查看下面这篇博文：kubernetes ceph-csi分析目录导航

external-provisioner源码分析（3）-组件启动参数分析

本文将对external-provisioner组件的启动参数进行分析。

基于tag v1.6.0

https://github.com/kubernetes-csi/external-provisioner/releases/tag/v1.6.0

关联链接

external-provisioner组件的源码分析分为三部分：
（1）主体处理逻辑分析；
（2）main方法与Leader选举分析；
（3）组件启动参数分析。

external-provisioner组件启动参数列表

具体参考https://github.com/kubernetes-csi/external-provisioner#command-line-options

var (
	master               = flag.String("master", "", "Master URL to build a client config from. Either this or kubeconfig needs to be set if the provisioner is being run out of cluster.")
	kubeconfig           = flag.String("kubeconfig", "", "Absolute path to the kubeconfig file. Either this or master needs to be set if the provisioner is being run out of cluster.")
	csiEndpoint          = flag.String("csi-address", "/run/csi/socket", "The gRPC endpoint for Target CSI Volume.")
	_                    = deprecatedflags.Add("connection-timeout")
	volumeNamePrefix     = flag.String("volume-name-prefix", "pvc", "Prefix to apply to the name of a created volume.")
	volumeNameUUIDLength = flag.Int("volume-name-uuid-length", -1, "Truncates generated UUID of a created volume to this length. Defaults behavior is to NOT truncate.")
	showVersion          = flag.Bool("version", false, "Show version.")
	retryIntervalStart   = flag.Duration("retry-interval-start", time.Second, "Initial retry interval of failed provisioning or deletion. It doubles with each failure, up to retry-interval-max.")
	retryIntervalMax     = flag.Duration("retry-interval-max", 5*time.Minute, "Maximum retry interval of failed provisioning or deletion.")
	workerThreads        = flag.Uint("worker-threads", 100, "Number of provisioner worker threads, in other words nr. of simultaneous CSI calls.")
	finalizerThreads     = flag.Uint("cloning-protection-threads", 1, "Number of simultaniously running threads, handling cloning finalizer removal")
	operationTimeout     = flag.Duration("timeout", 10*time.Second, "Timeout for waiting for creation or deletion of a volume")
	_                    = deprecatedflags.Add("provisioner")

	enableLeaderElection    = flag.Bool("enable-leader-election", false, "Enables leader election. If leader election is enabled, additional RBAC rules are required. Please refer to the Kubernetes CSI documentation for instructions on setting up these RBAC rules.")
	leaderElectionType      = flag.String("leader-election-type", "endpoints", "the type of leader election, options are 'endpoints' (default) or 'leases' (strongly recommended). The 'endpoints' option is deprecated in favor of 'leases'.")
	leaderElectionNamespace = flag.String("leader-election-namespace", "", "Namespace where the leader election resource lives. Defaults to the pod namespace if not set.")
	strictTopology          = flag.Bool("strict-topology", false, "Passes only selected node topology to CreateVolume Request, unlike default behavior of passing aggregated cluster topologies that match with topology keys of the selected node.")
	extraCreateMetadata     = flag.Bool("extra-create-metadata", false, "If set, add pv/pvc metadata to plugin create requests as parameters.")

	metricsAddress = flag.String("metrics-address", "", "The TCP network address where the prometheus metrics endpoint will listen (example: `:8080`). The default is empty string, which means metrics endpoint is disabled.")
	metricsPath    = flag.String("metrics-path", "/metrics", "The HTTP path where prometheus metrics will be exposed. Default is `/metrics`.")
	
	featureGates        map[string]bool
	provisionController *controller.ProvisionController
	version             = "unknown"

)

func main() {
	var config *rest.Config
	var err error

	flag.Var(utilflag.NewMapStringBool(&featureGates), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/experimental features. "+
		"Options are:\n"+strings.Join(utilfeature.DefaultFeatureGate.KnownFeatures(), "\n"))

	klog.InitFlags(nil)
	flag.CommandLine.AddGoFlagSet(goflag.CommandLine)
	flag.Set("logtostderr", "true")
	flag.Parse()
	
......

external-provisioner容器部署的启动参数配置

    ...
    args:
        - "--csi-address=$(ADDRESS)"
        - "--v=5"
        - "--timeout=150s"
        - "--retry-interval-start=500ms"
        - "--enable-leader-election=true"
        - "--leader-election-type=leases"
        - "--feature-gates=Topology=true"
    env:
        - name: ADDRESS
            value: unix:///csi/csi-provisioner.sock
    imagePullPolicy: "Always"
    volumeMounts:
    - name: socket-dir
      mountPath: /csi
  volumes：
  - name: socket-dir
    emptyDir: {
      medium: "Memory"
    }
  ...

下面是部分参数解析。其他参数请参考：https://github.com/kubernetes-csi/external-provisioner#command-line-options

csi-address

ceph-csi组件暴露的grpc服务socket地址，external-provisioner组件将与该socket地址通信，发出创建、删除存储的请求。默认值为/run/csi/socket。

timeout

创建存储与删除存储请求的超时时间，默认10秒。

enable-leader-election

是否开启leader选举，配置值为true时开启，默认值为false。

leader-election-type

leader选举时使用的锁类型，包括两种，默认的endpoint与官方推荐的lease。

leader-election-namespace

leader选举所使用的锁对象存储在哪个命令空间，默认存储在external-provisioner pod所在的命名空间。

extra-create-metadata

设置为true后，创建存储时，将额外增加请求参数：pvc的名称、命名空间、pv的名称，默认值为false。

worker-threads

同时执行CreateVolume/DeleteVolume操作的worker数量，默认值为100。

retry-interval-start

创建、删除存储失败后的初始重试时间间隔，默认值为1秒。每一次失败，重试时间间隔会加倍，直到达到--retry-interval-max配置的上限值。

retry-interval-max

创建、删除存储失败后的最大重试时间间隔，默认值为5分钟。

volume-name-prefix

创建pv时给pv名称加的前缀，默认值为pvc。

feature-gates

特性配置。

配置示例：--feature-gates=Topology=true，存储拓扑相关，具体使用请参考：
https://kubernetes.io/zh/blog/2018/10/11/kubernetes-中的拓扑感知数据卷供应/
https://kubernetes-csi.github.io/docs/topology.html

kube-api-qps与kube-api-burst

用于kube-client与kube-apiserver通信时客户端kube-client的限流。
限流实现上是令牌桶算法，kube-api-qps可以看作是每秒产生令牌的速度，而kube-api-burst可以看作是令牌桶的大小，kube-client发送给kube-apiserver的请求需要拿到令牌桶里的令牌后才能发送。
其中kube-api-qps默认值为5，kube-api-burst默认值为10。