Kubernetes 的 kube-apiserver 实现

[junnplus]

kube-apiserver 作为 k8s 中一个重要的组件存在。

// cmd/kube-apiserver/app/server.go
// NewAPIServerCommand creates a *cobra.Command object with default parameters
func NewAPIServerCommand() *cobra.Command {
	s := options.NewServerRunOptions()
	cmd := &cobra.Command{
		Use: "kube-apiserver",
		Long: `The Kubernetes API server validates and configures data
for the api objects which include pods, services, replicationcontrollers, and
others. The API Server services REST operations and provides the frontend to the
cluster's shared state through which all other components interact.`,
		RunE: func(cmd *cobra.Command, args []string) error {
			verflag.PrintAndExitIfRequested()
			utilflag.PrintFlags(cmd.Flags())

			// set default options
			completedOptions, err := Complete(s)
			if err != nil {
				return err
			}
...

			return Run(completedOptions, genericapiserver.SetupSignalHandler())
		},
	}

...
	return cmd
}

// Run runs the specified APIServer.  This should never exit.
func Run(completeOptions completedServerRunOptions, stopCh <-chan struct{}) error {
	// To help debugging, immediately log version
	klog.Infof("Version: %+v", version.Get())

	server, err := CreateServerChain(completeOptions, stopCh)
	if err != nil {
		return err
	}

	prepared, err := server.PrepareRun()
	if err != nil {
		return err
	}

	return prepared.Run(stopCh)
}

// CreateServerChain creates the apiservers connected via delegation.
func CreateServerChain(completedOptions completedServerRunOptions, stopCh <-chan struct{}) (*aggregatorapiserver.APIAggregator, error) {
...
	apiExtensionsServer, err := createAPIExtensionsServer(apiExtensionsConfig, genericapiserver.NewEmptyDelegate())
...

	kubeAPIServer, err := CreateKubeAPIServer(kubeAPIServerConfig, apiExtensionsServer.GenericAPIServer, admissionPostStartHook)

...
	aggregatorServer, err := createAggregatorServer(aggregatorConfig, kubeAPIServer.GenericAPIServer, apiExtensionsServer.Informers)
...

	return aggregatorServer, nil
}

kube-apiserver 主要由下面三个 lib 组成

• apiserver
• apiextensions-apiserver
• kube-aggregator

[junnplus]

apiserver

Library for writing a Kubernetes-style API server.

https://github.com/Junnplus/blog/issues/44

[junnplus]

apiextensions-apiserver