聚焦目标
理解kube-apiserver是中的管理核心资源的KubeAPIServer是怎么启动的
目录
GenericServer
// 在APIExtensionsServer、KubeAPIServer和AggregatorServer三种Server启动时，我们都能发现这么一个函数
// APIExtensionsServer
genericServer, err := c.GenericConfig.New("apiextensions-apiserver", delegationTarget)
// KubeAPIServer
s, err := c.GenericConfig.New("kube-apiserver", delegationTarget)
// AggregatorServer
genericServer, err := c.GenericConfig.New("kube-aggregator", delegationTarget)
// 都通过GenericConfig创建了genericServer，我们先大致浏览下
func (c completedConfig) New(name string, delegationTarget DelegationTarget) (*GenericAPIServer, error) {
// 新建Handler
apiServerHandler := NewAPIServerHandler(name, c.Serializer, handlerChainBuilder, delegationTarget.UnprotectedHandler())
// 实例化一个Server
s := &GenericAPIServer{
...
}
// 处理钩子hook操作
for k, v := range delegationTarget.PostStartHooks() {
s.postStartHooks[k] = v
}
for k, v := range delegationTarget.PreShutdownHooks() {
s.preShutdownHooks[k] = v
}
// 健康监测
for _, delegateCheck := range delegationTarget.HealthzChecks() {
skip := false
for _, existingCheck := range c.HealthzChecks {
if existingCheck.Name() == delegateCheck.Name() {
skip = true
break
}
}
if skip {
continue
}
s.AddHealthChecks(delegateCheck)
}
// 安装API相关参数，这个是重点
installAPI(s, c.Config)
return s, nil
}
NewAPIServerHandler
func NewAPIServerHandler(name string, s runtime.NegotiatedSerializer, handlerChainBuilder HandlerChainBuilderFn, notFoundHandler http.Handler) *APIServerHandler {
// 采用了 github.com/emicklei/go-restful 这个库作为 RESTful 接口的设计，目前了解即可
gorestfulContainer := restful.NewContainer()
}
installAPI
func installAPI(s *GenericAPIServer, c *Config) {
// 添加 /index.html 路由规则
if c.EnableIndex {
routes.Index{
}.Install(s.listedPathProvider, s.Handler.NonGoRestfulMux)
}
// 添加go语言 /pprof 的路由规则，常用于性能分析
if c.EnableProfiling {
routes.Profiling{
}.Install(s.Handler.NonGoRestfulMux)
if c.EnableContentionProfiling {
goruntime.SetBlockProfileRate(1)
}
routes.DebugFlags{
}.Install(s.Handler.NonGoRestfulMux, "v", routes.StringFlagPutHandler(logs.GlogSetter))
}
// 添加监控相关的 /metrics 的指标路由规则
if c.EnableMetrics {
if c.EnableProfiling {
routes.MetricsWithReset{
}.Install(s.Handler.NonGoRestfulMux)
} else {
routes.DefaultMetrics{
}.Install(s.Handler.NonGoRestfulMux)
}
}
// 添加版本 /version 的路由规则
routes.Version{
Version: c.Version}.Install(s.Handler.GoRestfulContainer)
// 开启服务发现
if c.EnableDiscovery {
s.Handler.GoRestfulContainer.Add(s.DiscoveryGroupManager.WebService())
}
if feature.DefaultFeatureGate.Enabled(features.APIPriorityAndFairness) {
c.FlowControl.Install(s.Handler.NonGoRestfulMux)
}
}
Apiserver
func (c completedConfig) New(delegationTarget genericapiserver.DelegationTarget) (*Master, error) {
// genericServer的初始化
s, err := c.GenericConfig.New("kube-apiserver", delegationTarget)
// 核心KubeAPIServer的实例化
m := &Master{
GenericAPIServer: s,
ClusterAuthenticationInfo: c.ExtraConfig.ClusterAuthenticationInfo,
}
// 注册Legacy API的注册
if c.ExtraConfig.APIResourceConfigSource.VersionEnabled(apiv1.SchemeGroupVersion) {
legacyRESTStorageProvider := corerest.LegacyRESTStorageProvider{
}
if err := m.InstallLegacyAPI(&c, c.GenericConfig.RESTOptionsGetter, legacyRESTStorageProvider); err != nil {
return nil, err
}
}
// REST接口的存储定义，可以看到很多k8s上的常见定义，比如node节点/storage存储/event事件等等
restStorageProviders := []RESTStorageProvider{
authenticationrest.RESTStorageProvider{
Authenticator: c.GenericConfig.Authentication.Authenticator, APIAudiences: c.GenericConfig.Authentication.APIAudiences},
authorizationrest.RESTStorageProvider{
Authorizer: c.GenericConfig.Authorization.Authorizer, RuleResolver: c.GenericConfig.RuleResolver},
autoscalingrest.RESTStorageProvider{
},
batchrest.RESTStorageProvider{
},
certificatesrest.RESTStorageProvider{
},
coordinationrest.RESTStorageProvider{
},
discoveryrest.StorageProvider{
},
extensionsrest.RESTStorageProvider{
},
networkingrest.RESTStorageProvider{
},
noderest.RESTStorageProvider{
},
policyrest.RESTStorageProvider{
},
rbacrest.RESTStorageProvider{
Authorizer: c.GenericConfig.Authorization.Authorizer},
schedulingrest.RESTStorageProvider{
},
settingsrest.RESTStorageProvider{
},
storagerest.RESTStorageProvider{
},
flowcontrolrest.RESTStorageProvider{
},
// keep apps after extensions so legacy clients resolve the extensions versions of shared resource names.
// See https://github.com/kubernetes/kubernetes/issues/42392
appsrest.StorageProvider{
},
admissionregistrationrest.RESTStorageProvider{
},
eventsrest.RESTStorageProvider{
TTL: c.ExtraConfig.EventTTL},
}
// 注册API
if err := m.InstallAPIs(c.ExtraConfig.APIResourceConfigSource, c.GenericConfig.RESTOptionsGetter, restStorageProviders...); err != nil {
return nil, err
}
// 添加Hook
m.GenericAPIServer.AddPostStartHookOrDie("start-cluster-authentication-info-controller", func(hookContext genericapiserver.PostStartHookContext) error {
})
return m, nil
}
注册API的关键在InstallLegacyAPI和InstallAPIs，如果你对kubernetes的资源有一定的了解，会知道核心资源都放在Legacy中（如果不了解的话，点击函数看一下，就能有所有了解）
InstallLegacyAPI
func (m *Master) InstallLegacyAPI(c *completedConfig, restOptionsGetter generic.RESTOptionsGetter, legacyRESTStorageProvider corerest.LegacyRESTStorageProvider) error {
// RESTStorage的初始化
legacyRESTStorage, apiGroupInfo, err := legacyRESTStorageProvider.NewLegacyRESTStorage(restOptionsGetter)
// 前缀为 /api，注册上对应的Version和Resource
// Pod作为核心资源，没有Group的概念
if err := m.GenericAPIServer.InstallLegacyAPIGroup(genericapiserver.DefaultLegacyAPIPrefix, &apiGroupInfo); err != nil {
return fmt.Errorf("error in registering group versions: %v", err)
}
return nil
}
// 我们再细看这个RESTStorage的初始化
func (c LegacyRESTStorageProvider) NewLegacyRESTStorage(restOptionsGetter generic.RESTOptionsGetter) (LegacyRESTStorage, genericapiserver.APIGroupInfo, error) {
// pod 模板
podTemplateStorage, err := podtemplatestore.NewREST(restOptionsGetter)
// event事件
eventStorage, err := eventstore.NewREST(restOptionsGetter, uint64(c.EventTTL.Seconds()))
// limitRange资源限制
limitRangeStorage, err := limitrangestore.NewREST(restOptionsGetter)
// resourceQuota资源配额
resourceQuotaStorage, resourceQuotaStatusStorage, err := resourcequotastore.NewREST(restOptionsGetter)
// secret加密
secretStorage, err := secretstore.NewREST(restOptionsGetter)
// PV 存储
persistentVolumeStorage, persistentVolumeStatusStorage, err := pvstore.NewREST(restOptionsGetter)
// PVC 存储
persistentVolumeClaimStorage, persistentVolumeClaimStatusStorage, err := pvcstore.NewREST(restOptionsGetter)
// ConfigMap 配置
configMapStorage, err := configmapstore.NewREST(restOptionsGetter)
// 等等核心资源，暂不一一列举
// pod模板，我们的示例nginx-pod属于这个类型的资源
podStorage, err := podstore.NewStorage()
// 保存storage的对应关系
restStorageMap := map[string]rest.Storage{
"pods": podStorage.Pod,
"pods/attach": podStorage.Attach,
"pods/status": podStorage.Status,
"pods/log": podStorage.Log,
"pods/exec": podStorage.Exec,
"pods/portforward": podStorage.PortForward,
"pods/proxy": podStorage.Proxy,
"pods/binding": podStorage.Binding,
"bindings": podStorage.LegacyBinding,
...
}
}
Create Pod
// 查看Pod初始化
func NewStorage(optsGetter generic.RESTOptionsGetter, k client.ConnectionInfoGetter, proxyTransport http.RoundTripper, podDisruptionBudgetClient policyclient.PodDisruptionBudgetsGetter) (PodStorage, error) {
store := &genericregistry.Store{
NewFunc: func() runtime.Object {
return &api.Pod{
} },
NewListFunc: func() runtime.Object {
return &api.PodList{
} },
PredicateFunc: registrypod.MatchPod,
DefaultQualifiedResource: api.Resource("pods"),
// 增改删的策略
CreateStrategy: registrypod.Strategy,
UpdateStrategy: registrypod.Strategy,
DeleteStrategy: registrypod.Strategy,
ReturnDeletedObject: true,
TableConvertor: printerstorage.TableConvertor{
TableGenerator: printers.NewTableGenerator().With(printersinternal.AddHandlers)},
}
}
// 查看 Strategy 的初始化
var Strategy = podStrategy{
legacyscheme.Scheme, names.SimpleNameGenerator}
// 又查询到Scheme的初始化。Schema可以理解为Kubernetes的注册表，即所有的资源类型必须先注册进Schema才可使用
var Scheme = runtime.NewScheme()
