源码版本
Kubernetes v1.5.0
简介
k8s里面有各种资源，如Pod、Service、RC、namespaces等资源，用户操作的其实也就是这一大堆资源。但这些资源并不是杂乱无章的，使用了GroupVersion的方式组织在一起。每一种资源都属于一个Group，而资源还有版本之分，如v1、v1beta1等。
k8s目前正在使用的API groups：
"core" group：它的REST path是api/v1
"extensions" group：它的REST path是/apis/extensions/v1beta1
"autoscaling", "abac" ...
服务器的URL的格式：/prefix/group/version/... (例如：/apis/extensions/v1beta1)
重要结构体
APIGroupVersion：对API资源的组织，里面包含了Storage、GroupVersion、Mapper、Serializer、Convertor等成员。Storage是etcd的接口，这是一个map类型，每一种资源都会与etcd建立一个连接；GroupVersion表示该APIGroupVersion属于哪个Group、哪个version；Serializer用于序列化，反序列化；Convertor提供各个不同版本进行转化的接口；Mapper实现了RESTMapper接口。
type APIGroupVersion struct {
// key存在对象的url，value是一个rest.Storage，用于对接etcd存储
Storage map[string]rest.Storage
// 该group的prefix，例如核心组的Root是'/api'
Root string
// 包含类似'api/v1'这样的string，用于标识这个实例
GroupVersion unversioned.GroupVersion
// OptionsExternalVersion controls the Kubernetes APIVersion used for common objects in the apiserver
// schema like api.Status, api.DeleteOptions, and api.ListOptions. Other implementors may
// define a version "v1beta1" but want to use the Kubernetes "v1" internal objects. If
// empty, defaults to GroupVersion.
OptionsExternalVersion *unversioned.GroupVersion
// 关键性成员
Mapper meta.RESTMapper
// 对象序列化和反序列化器
Serializer runtime.NegotiatedSerializer
ParameterCodec runtime.ParameterCodec
// 以下4个都是被赋值为Scheme结构
Typer runtime.ObjectTyper
Creater runtime.ObjectCreater
// 相互转换任意api版本的对象，需要事先注册转换函数
Convertor runtime.ObjectConvertor
Copier runtime.ObjectCopier
Linker runtime.SelfLinker
// 用于访问许可控制
Admit admission.Interface
Context api.RequestContextMapper
MinRequestTimeout time.Duration
// SubresourceGroupVersionKind contains the GroupVersionKind overrides for each subresource that is
// accessible from this API group version. The GroupVersionKind is that of the external version of
// the subresource. The key of this map should be the path of the subresource. The keys here should
// match the keys in the Storage map above for subresources.
SubresourceGroupVersionKind map[string]unversioned.GroupVersionKind
// ResourceLister is an interface that knows how to list resources
// for this API Group.
ResourceLister APIResourceLister
}APIGroupVersion的创建接口是pkg/genericapiserver/genericapiserver.go中的newAPIGroupVersion()接口，在接口在创建APIGroupVersion还用到了好几个别的结构：APIGroupInfo、Scheme、GroupMeta。下面一个一个介绍：
APIGroupInfo:
type APIGroupInfo struct {
// 该Group的元信息
GroupMeta apimachinery.GroupMeta
// 不同版本的所有的Storage
VersionedResourcesStorageMap map[string]map[string]rest.Storage
// OptionsExternalVersion controls the APIVersion used for common objects in the
// schema like api.Status, api.DeleteOptions, and api.ListOptions. Other implementors may
// define a version "v1beta1" but want to use the Kubernetes "v1" internal objects.
// If nil, defaults to groupMeta.GroupVersion.
// TODO: Remove this when https://github.com/kubernetes/kubernetes/issues/19018 is fixed.
OptionsExternalVersion *unversioned.GroupVersion
// core group的话，对应的就是api.Scheme
Scheme *runtime.Scheme
// NegotiatedSerializer controls how this group encodes and decodes data
NegotiatedSerializer runtime.NegotiatedSerializer
// ParameterCodec performs conversions for query parameters passed to API calls
ParameterCodec runtime.ParameterCodec
// 所有resources信息,key就是resource的path
// 比如：key为"replicationcontrollers/scale",GroupVersionKind: autoscaling, v1, Scale
SubresourceGroupVersionKind map[string]unversioned.GroupVersionKind
}Scheme: 用于API资源之间的序列化、反序列化、版本转换。Scheme里面还有好几个map，前面的结构体存储的都是unversioned.GroupVersionKind、unversioned.GroupVersion这些东西，这些东西本质上只是表示资源的字符串标识，Scheme存储了对应着标志的具体的API资源的结构体，即relect.Type
type Scheme struct {
// versionMap allows one to figure out the go type of an object with
// the given version and name.
gvkToType map[unversioned.GroupVersionKind]reflect.Type
// typeToGroupVersion allows one to find metadata for a given go object.
// The reflect.Type we index by should *not* be a pointer.
typeToGVK map[reflect.Type][]unversioned.GroupVersionKind
// unversionedTypes are transformed without conversion in ConvertToVersion.
unversionedTypes map[reflect.Type]unversioned.GroupVersionKind
// unversionedKinds are the names of kinds that can be created in the context of any group
// or version
// TODO: resolve the status of unversioned types.
unversionedKinds map[string]reflect.Type
// Map from version and resource to the corresponding func to convert
// resource field labels in that version to internal version.
fieldLabelConversionFuncs map[string]map[string]FieldLabelConversionFunc
// defaulterFuncs is an array of interfaces to be called with an object to provide defaulting
// the provided object must be a pointer.
defaulterFuncs map[reflect.Type]func(interface{})
// converter stores all registered conversion functions. It also has
// default coverting behavior.
converter *conversion.Converter
// cloner stores all registered copy functions. It also has default
// deep copy behavior.
cloner *conversion.Cloner
}GroupMeta： 主要包括Group的元信息，里面的成员RESTMapper，与APIGroupVersion一样，其实APIGroupVersion的RESTMapper直接取之于GroupMeta的RESTMapper.一个Group可能包含多个版本，存储在GroupVersion中，而GroupVersion是默认存储在etcd中的版本。
type GroupMeta struct {
// 默认版本
GroupVersion unversioned.GroupVersion
// 该Group中可能会有多个版本，该字段就包含了所有的versions
GroupVersions []unversioned.GroupVersion
// 用于编解码
Codec runtime.Codec
// SelfLinker can set or get the SelfLink field of all API types.
// TODO: when versioning changes, make this part of each API definition.
// TODO(lavalamp): Combine SelfLinker & ResourceVersioner interfaces, force all uses
// to go through the InterfacesFor method below.
SelfLinker runtime.SelfLinker
// 用于类型，对象之间的转换
RESTMapper meta.RESTMapper
// InterfacesFor returns the default Codec and ResourceVersioner for a given version
// string, or an error if the version is not known.
// TODO: make this stop being a func pointer and always use the default
// function provided below once every place that populates this field has been changed.
InterfacesFor func(version unversioned.GroupVersion) (*meta.VersionInterfaces, error)
// InterfacesByVersion stores the per-version interfaces.
InterfacesByVersion map[unversioned.GroupVersion]*meta.VersionInterfaces
}RESTMapper： 用于管理所有对象的信息。外部要获取的话，直接通过version,group获取到RESTMapper，然后通过kind类型可以获取到对应的信息。该RESTMapper其实是实现了一个DefaultRESTMapper结构。
type DefaultRESTMapper struct {
defaultGroupVersions []unversioned.GroupVersion
resourceToKind map[unversioned.GroupVersionResource]unversioned.GroupVersionKind
kindToPluralResource map[unversioned.GroupVersionKind]unversioned.GroupVersionResource
kindToScope map[unversioned.GroupVersionKind]RESTScope
singularToPlural map[unversioned.GroupVersionResource]unversioned.GroupVersionResource
pluralToSingular map[unversioned.GroupVersionResource]unversioned.GroupVersionResource
interfacesFunc VersionInterfacesFunc
// aliasToResource is used for mapping aliases to resources
aliasToResource map[string][]string
}APIRegistrationManager：这个结构体主要提供了已经"registered"的概念，将所有已经注册的，已经激活的，第三方的的GroupVersions进行了汇总，还包括了各个GroupVersion的GroupMeta(元数据)。
type APIRegistrationManager struct {
// 所以已经registered的GroupVersions
registeredVersions map[unversioned.GroupVersion]struct{}
// 第三方注册的GroupVersions,这些都向apiServer动态注册的
thirdPartyGroupVersions []unversioned.GroupVersion
// 所有已经enable的GroupVersions，可以通过EnableVersions()将要enable的GroupVersion加入进来。
// 只有enable了，才能使用对应的GroupVersion
enabledVersions map[unversioned.GroupVersion]struct{}
// 所有groups的GroupMeta
groupMetaMap map[string]*apimachinery.GroupMeta
// 跟环境变量'KUBE_API_VERSIONS'有关
envRequestedVersions []unversioned.GroupVersion
}APIRegistrationManager初始化
该结构的路径：pkg/apimachinery/registered/registered.go
在该文件中我们能看到初始化了一个DefaultAPIRegistrationManager对象：
var (
DefaultAPIRegistrationManager = NewOrDie(os.Getenv("KUBE_API_VERSIONS"))
)进入NewOrDie()接口看下：
func NewOrDie(kubeAPIVersions string) *APIRegistrationManager {
m, err := NewAPIRegistrationManager(kubeAPIVersions)
if err != nil {
glog.Fatalf("Could not construct version manager: %v (KUBE_API_VERSIONS=%q)", err, kubeAPIVersions)
}
return m
}
func NewAPIRegistrationManager(kubeAPIVersions string) (*APIRegistrationManager, error) {
m := &APIRegistrationManager{
registeredVersions: map[unversioned.GroupVersion]struct{}{},
thirdPartyGroupVersions: []unversioned.GroupVersion{},
enabledVersions: map[unversioned.GroupVersion]struct{}{},
groupMetaMap: map[string]*apimachinery.GroupMeta{},
envRequestedVersions: []unversioned.GroupVersion{},
}
// 如果环境变量KUBE_API_VERSIONS进行了设置的话，进行遍历
if len(kubeAPIVersions) != 0 {
// 通过逗号进行分隔
for _, version := range strings.Split(kubeAPIVersions, ",") {
// 解析version并转换成GroupVersion格式
// 一般这里的version是group/version格式，比如'/api/v1'
gv, err := unversioned.ParseGroupVersion(version)
if err != nil {
return nil, fmt.Errorf("invalid api version: %s in KUBE_API_VERSIONS: %s.",
version, kubeAPIVersions)
}
// 然后将该gv放入envRequestedVersions
m.envRequestedVersions = append(m.envRequestedVersions, gv)
}
}
// 否则返回一个空的APIRegistrationManager
return m, nil
}瞅了下我们正在使用的环境，没有配置KUBE_API_VERSIONS,即返回了一个空的结构，还提供了好多方法。
var (
ValidateEnvRequestedVersions = DefaultAPIRegistrationManager.ValidateEnvRequestedVersions
AllPreferredGroupVersions = DefaultAPIRegistrationManager.AllPreferredGroupVersions
RESTMapper = DefaultAPIRegistrationManager.RESTMapper
GroupOrDie = DefaultAPIRegistrationManager.GroupOrDie
AddThirdPartyAPIGroupVersions = DefaultAPIRegistrationManager.AddThirdPartyAPIGroupVersions
IsThirdPartyAPIGroupVersion = DefaultAPIRegistrationManager.IsThirdPartyAPIGroupVersion
RegisteredGroupVersions = DefaultAPIRegistrationManager.RegisteredGroupVersions
IsRegisteredVersion = DefaultAPIRegistrationManager.IsRegisteredVersion
IsRegistered = DefaultAPIRegistrationManager.IsRegistered
Group = DefaultAPIRegistrationManager.Group
EnabledVersionsForGroup = DefaultAPIRegistrationManager.EnabledVersionsForGroup
EnabledVersions = DefaultAPIRegistrationManager.EnabledVersions
IsEnabledVersion = DefaultAPIRegistrationManager.IsEnabledVersion
IsAllowedVersion = DefaultAPIRegistrationManager.IsAllowedVersion
EnableVersions = DefaultAPIRegistrationManager.EnableVersions
RegisterGroup = DefaultAPIRegistrationManager.RegisterGroup
RegisterVersions = DefaultAPIRegistrationManager.RegisterVersions
InterfacesFor = DefaultAPIRegistrationManager.InterfacesFor
)在分析apiServer的启动流程的时候，你会发现初始化ServerRunOptions对象时，用到了好多上面的变量，比如：
路径：pkg/genericapiserver/options/server_run_options.go
func NewServerRunOptions() *ServerRunOptions {
return &ServerRunOptions{
AdmissionControl: "AlwaysAdmit",
。。。
// 这里就使用了AllPreferredGroupVersions接口
DefaultStorageVersions: registered.AllPreferredGroupVersions(),
。。。
StorageVersions: registered.AllPreferredGroupVersions(),
}
}上面就使用到了registered.AllPreferredGroupVersions()接口,顺便看下接口具体实现：
func (m *APIRegistrationManager) AllPreferredGroupVersions() string {
// 如果没有注册groupMeta的话，这里就==0
// 不过不可能没有注册，至于在哪里进行注册就得看下后面介绍的GroupMeta初始化了
if len(m.groupMetaMap) == 0 {
return ""
}
var defaults []string
for _, groupMeta := range m.groupMetaMap {
defaults = append(defaults, groupMeta.GroupVersion.String())
}
sort.Strings(defaults)
return strings.Join(defaults, ",")
}该接口比较简单，就是从m.groupMetaMap中取出所有的groupMeta，然后通过逗号拼接成"group1/version1,group2/version2,..."的字符串。
这里可以想一下，既然有list，那总得有groupMeta啊。而我们看APIRegistrationManager的初始化，如果没有设置KUBE_API_VERSIONS环境变量的话，根本就没有groupMeta。
既然不可能没有groupMeta，那肯定得从别的地方进行register & enable。我们可以从APIRegistrationManager提供的RegisterGroup方法入手：
func (m *APIRegistrationManager) RegisterGroup(groupMeta apimachinery.GroupMeta) error {
groupName := groupMeta.GroupVersion.Group
if _, found := m.groupMetaMap[groupName]; found {
return fmt.Errorf("group %v is already registered", m.groupMetaMap)
}
m.groupMetaMap[groupName] = &groupMeta
return nil
}该RegisterGroup接口的入参就是GroupMeta,所以我们得继续查看该结构的初始化了。
GroupMeta初始化
k8s现阶段，API一共分为13个Group：Core、apps、authentication、authorization、autoscaling、batch、certificates、componentconfig、extensions、imagepolicy、policy、rbac、storage。其中Core的Group Name为空，它包含的API是最核心的API,如Pod、Service等，它的代码位于pkg/api下面，其它12个Group代码位于pkg/apis。每个目录下都有一个install目录，里面有一个install.go文件，接着通过init()负责初始化。这些程序都是通过下列文件进行import：
路径： pkg/master/import_known_versions.go
package master
// These imports are the API groups the API server will support.
import (
"fmt"
_ "k8s.io/kubernetes/pkg/api/install"
"k8s.io/kubernetes/pkg/apimachinery/registered"
_ "k8s.io/kubernetes/pkg/apis/apps/install"
_ "k8s.io/kubernetes/pkg/apis/authentication/install"
_ "k8s.io/kubernetes/pkg/apis/authorization/install"
_ "k8s.io/kubernetes/pkg/apis/autoscaling/install"
_ "k8s.io/kubernetes/pkg/apis/batch/install"
_ "k8s.io/kubernetes/pkg/apis/certificates/install"
_ "k8s.io/kubernetes/pkg/apis/componentconfig/install"
_ "k8s.io/kubernetes/pkg/apis/extensions/install"
_ "k8s.io/kubernetes/pkg/apis/imagepolicy/install"
_ "k8s.io/kubernetes/pkg/apis/policy/install"
_ "k8s.io/kubernetes/pkg/apis/rbac/install"
_ "k8s.io/kubernetes/pkg/apis/storage/install"
)一共import了13个group。其中"k8s.io/kubernetes/pkg/api/install"就是Core Group，我们就以它为例，查看下对应的install.go文件。
路径： pkg/api/install/install.go
var availableVersions = []unversioned.GroupVersion{v1.SchemeGroupVersion}
func init() {
// 进行Versions注册，其实就是存入APIRegistrationManager.registeredVersions中
registered.RegisterVersions(availableVersions)
externalVersions := []unversioned.GroupVersion{}
for _, v := range availableVersions {
// 判断下是否已经注册，并追加成一个切片
if registered.IsAllowedVersion(v) {
externalVersions = append(externalVersions, v)
}
}
if len(externalVersions) == 0 {
glog.V(4).Infof("No version is registered for group %v", api.GroupName)
return
}
// 再进行enable，其实就是存入APIRegistrationManager.enabledVersions
if err := registered.EnableVersions(externalVersions...); err != nil {
glog.V(4).Infof("%v", err)
return
}
// 该接口比较关键，进行单独介绍
if err := enableVersions(externalVersions); err != nil {
glog.V(4).Infof("%v", err)
return
}
}首先定义了一个切片availableVersions，里面只有一个元素v1.SchemeGroupVersion:
const GroupName = ""
var SchemeGroupVersion = unversioned.GroupVersion{Group: GroupName, Version: "v1"}根据该元素的定义，可以看出availableVersions就定义了一个GroupName为空，Version是'v1'的GroupVersion。接着把该GroupVersion放入APIRegistrationManager的registeredVersions和enabledVersions中。
registered的几个接口实现比较简单不进行介绍了，但是执行的enableVersions()是重头戏，我们继续深入：
func enableVersions(externalVersions []unversioned.GroupVersion) error {
// 字面意思：将所有的Versions添加到Scheme
// 又牵扯到Scheme，后面会介绍Scheme的初始化
// 越深入看牵扯出的概念越多，该接口也很重要，需要耐心层层挖掘
addVersionsToScheme(externalVersions...)
// 将一个GroupVersion作为默认的,即'/api/v1'
preferredExternalVersion := externalVersions[0]
// 就是这里！ 进行了GroupMeta的初始化。这就是我们这小节要看的关键
groupMeta := apimachinery.GroupMeta{
GroupVersion: preferredExternalVersion,
GroupVersions: externalVersions,
// RESTMapper也是关键所在，下面也会单做一节进行介绍
RESTMapper: newRESTMapper(externalVersions),
SelfLinker: runtime.SelfLinker(accessor),
InterfacesFor: interfacesFor,
}
// 前面都是register和enable了versions，这里才是进行了Group的register
// 该接口其实就是以第一个GroupVersion的groupName为key，groupMeta为value
// 对APIRegistrationManager的groupMetaMap,进行了赋值
if err := registered.RegisterGroup(groupMeta); err != nil {
return err
}
return nil
}到这步，我们再结合之前APIRegistrationManager的初始化，就能知道groupMetaMap中应该有了好几组groupMeta。那在ServerRunOptions对象初始化中调用的registered.AllPreferredGroupVersions()接口,能返回好几个DefaultStorageVersions，至少肯定有'/api/v1'。至于别的groupMeta，需要再看下别的install.go，大同小异就不展开一个一个讲了。
groupMeta的初始化虽然结束了，但是这里又引出一个关键Scheme，那么继续下一小节吧。。
Scheme初始化
在上一节介绍enableVersions()函数时，第一行便是调用了addVersionsToScheme(externalVersions...),将GroupVersions加到Scheme。我们就来看下该接口:
func addVersionsToScheme(externalVersions ...unversioned.GroupVersion) {
// add the internal version to Scheme
if err := api.AddToScheme(api.Scheme); err != nil {
// Programmer error, detect immediately
panic(err)
}
// add the enabled external versions to Scheme
for _, v := range externalVersions {
if !registered.IsEnabledVersion(v) {
glog.Errorf("Version %s is not enabled, so it will not be added to the Scheme.", v)
continue
}
switch v {
case v1.SchemeGroupVersion:
if err := v1.AddToScheme(api.Scheme); err != nil {
// Programmer error, detect immediately
panic(err)
}
}
}
}接口中我们可以看到AddToScheme(api.Scheme)都是将GroupVersion加入到api.Scheme。我们先将上面的接口解析放放，先看下api.Scheme是如何初始化的：
路径：pkg/api/register.go
var Scheme = runtime.NewScheme()定义了Scheme，再看NewScheme()：
路径：pkg/runtime/scheme.go
func NewScheme() *Scheme {
// 定义空的Scheme
s := &Scheme{
gvkToType: map[unversioned.GroupVersionKind]reflect.Type{},
typeToGVK: map[reflect.Type][]unversioned.GroupVersionKind{},
unversionedTypes: map[reflect.Type]unversioned.GroupVersionKind{},
unversionedKinds: map[string]reflect.Type{},
cloner: conversion.NewCloner(),
fieldLabelConversionFuncs: map[string]map[string]FieldLabelConversionFunc{},
defaulterFuncs: map[reflect.Type]func(interface{}){},
}
// 创建converter，用于不同版本对象转换
s.converter = conversion.NewConverter(s.nameFunc)
// 增加一些转换函数
s.AddConversionFuncs(DefaultEmbeddedConversions()...)
// Enable map[string][]string conversions by default
if err := s.AddConversionFuncs(DefaultStringConversions...); err != nil {
panic(err)
}
if err := s.RegisterInputDefaults(&map[string][]string{}, JSONKeyMapper, conversion.AllowDifferentFieldTypeNames|conversion.IgnoreMissingFields); err != nil {
panic(err)
}
if err := s.RegisterInputDefaults(&url.Values{}, JSONKeyMapper, conversion.AllowDifferentFieldTypeNames|conversion.IgnoreMissingFields); err != nil {
panic(err)
}
return s
}上面就创建了一个空的Scheme。
知道哪里创建Scheme后，我们继续回到上面的addVersionsToScheme()函数。
其实主要就是看两个接口: api.AddToScheme()和v1.AddToScheme()。
先看第一个：
var (
SchemeBuilder = runtime.NewSchemeBuilder(addKnownTypes, addDefaultingFuncs)
AddToScheme = SchemeBuilder.AddToScheme
)通过runtime.NewSchemeBuilder()接口传入两个函数，然后创建了SchemeBuilder：
type SchemeBuilder []func(*Scheme) error
func (sb *SchemeBuilder) Register(funcs ...func(*Scheme) error) {
for _, f := range funcs {
*sb = append(*sb, f)
}
}
func NewSchemeBuilder(funcs ...func(*Scheme) error) SchemeBuilder {
var sb SchemeBuilder
sb.Register(funcs...)
return sb
}根据上面的定义和函数可以看出，SchemeBuilder就是一个接口切片，包含了addKnownTypes, addDefaultingFuncs两个接口。
SchemeBuilder定义好了之后，继续看AddToScheme:
func (sb *SchemeBuilder) AddToScheme(s *Scheme) error {
for _, f := range *sb {
if err := f(s); err != nil {
return err
}
}
return nil
}该函数就是调用了addKnownTypes, addDefaultingFuncs两个接口,我们一个一个看：
func addKnownTypes(scheme *runtime.Scheme) error {
if err := scheme.AddIgnoredConversionType(&unversioned.TypeMeta{}, &unversioned.TypeMeta{}); err != nil {
return err
}
// 把下列对象加入到Scheme中
// 该SchemeGroupVersion的GroupName为空，Version是"__internal"
// 所以该接口其实是把k8s内置的version添加到Scheme，而且每个group都有该步
scheme.AddKnownTypes(SchemeGroupVersion,
&Pod{},
&PodList{},
&PodStatusResult{},
&PodTemplate{},
&PodTemplateList{},
&ReplicationControllerList{},
&ReplicationController{},
&ServiceList{},
&Service{},
&ServiceProxyOptions{},
&NodeList{},
&Node{},
&NodeProxyOptions{},
&Endpoints{},
&EndpointsList{},
&Binding{},
&Event{},
&EventList{},
&List{},
&LimitRange{},
&LimitRangeList{},
&ResourceQuota{},
&ResourceQuotaList{},
&Namespace{},
&NamespaceList{},
&ServiceAccount{},
&ServiceAccountList{},
&Secret{},
&SecretList{},
&PersistentVolume{},
&PersistentVolumeList{},
&PersistentVolumeClaim{},
&PersistentVolumeClaimList{},
&DeleteOptions{},
&ListOptions{},
&PodAttachOptions{},
&PodLogOptions{},
&PodExecOptions{},
&PodProxyOptions{},
&ComponentStatus{},
&ComponentStatusList{},
&SerializedReference{},
&RangeAllocation{},
&ConfigMap{},
&ConfigMapList{},
)
// 在GroupName为空，Version为"v1"的groupVersion中，添加这些对象到Scheme
scheme.AddUnversionedTypes(Unversioned,
&unversioned.ExportOptions{},
&unversioned.Status{},
&unversioned.APIVersions{},
&unversioned.APIGroupList{},
&unversioned.APIGroup{},
&unversioned.APIResourceList{},
)
return nil
}查看AddKnownTypes()接口：
func (s *Scheme) AddKnownTypes(gv unversioned.GroupVersion, types ...Object) {
if len(gv.Version) == 0 {
panic(fmt.Sprintf("version is required on all types: %s %v", gv, types[0]))
}
for _, obj := range types {
t := reflect.TypeOf(obj)
if t.Kind() != reflect.Ptr {
panic("All types must be pointers to structs.")
}
t = t.Elem()
if t.Kind() != reflect.Struct {
panic("All types must be pointers to structs.")
}
gvk := gv.WithKind(t.Name())
s.gvkToType[gvk] = t
s.typeToGVK[t] = append(s.typeToGVK[t], gvk)
}
}该接口主要操作了s.gvkToType和s.typeToGVK，用于转换的目的。
综上得出，是将internal version添加到Scheme中。
为什么会有一个internal version呢？ 其实每一个Group都有一个internal version。而apiserver操作的也都是internal version.
举个例子：假如有一个创建Pod的请求来了，apiserver首先会将请求给反序列化，用户发过来的Pod请求往往是有版本的，比如v1，因此会反序列化为一个v1.Pod。apiserver会立即将这个v1.Pod利用convertor转换成internal.Pod，然后进行一些操作，最后要把它存到etcd里面去，etcd里面的Pod信息是有版本的，因此会先发生一次转换，将其转换为v1.Pod，然后序列化存入etcd。
这样看上去好像多此一举？其实这就是k8s对api多版本的支持，这样用户可以以一个v1beta1创建一个Pod,然后存入etcd的是一个相对稳定的版本，比如v1版本。
internal version添加完成后，继续回到最开始的addVersionsToScheme()函数，还要继续执行v1.AddToScheme(api.Scheme)函数.其实就是把v1版本的api添加到Scheme中，和添加internal版本一样。
我们看看v1.AddToScheme。
路径：pkg/api/v1/register.go
var (
SchemeBuilder = runtime.NewSchemeBuilder(addKnownTypes, addDefaultingFuncs, addConversionFuncs, addFastPathConversionFuncs)
AddToScheme = SchemeBuilder.AddToScheme
)这里可以看到v1相比较internal版本，还多了好几个函数addConversionFuncs, addFastPathConversionFuncs。
这些函数在执行AddToScheme()时其实都会要遍历执行，可以深入看下。其实就是向Scheme添加了转换函数，比如将v1.Pod转换为internal.Pod，将internal.Pod转换为v1.Pod。如果同时有v1,v2,v3会如何进行转换？其实也还是先统一转换成internal，然后再转换为相应的版本(v1,v2,v3).所以internal相当于转换的桥梁，更好的支持了不同版本的api。
到这里Scheme的初始化基本结束了。 上面讲GroupMeta初始化时还引出了关键性的RESTMapper，所以继续进行介绍。
RESTMapper初始化
该部分的初始化就直接看GroupMeta初始化时调用的接口newRESTMapper():
路径： pkg/api/install/install.go
func newRESTMapper(externalVersions []unversioned.GroupVersion) meta.RESTMapper {
// 这些是API最顶层的对象，可以理解为没有namespace的对象
// 根据有无namespace，对象分为两类：RESTScopeNamespace和RESTScopeRoot
rootScoped := sets.NewString(
"Node",
"Namespace",
"PersistentVolume",
"ComponentStatus",
)
// 需要忽略Scheme中如下的kinds
ignoredKinds := sets.NewString(
"ListOptions",
"DeleteOptions",
"Status",
"PodLogOptions",
"PodExecOptions",
"PodAttachOptions",
"PodProxyOptions",
"NodeProxyOptions",
"ServiceProxyOptions",
"ThirdPartyResource",
"ThirdPartyResourceData",
"ThirdPartyResourceList")
mapper := api.NewDefaultRESTMapper(externalVersions, interfacesFor, importPrefix, ignoredKinds, rootScoped)
return mapper
}其实所有的api资源可以分为两类：一类是有namespace，另一类是没有namespace。比如该接口中的Node、Namespace、PersistentVolume、ComponentStatus不属于任何namespace。ignoredKinds是下面接口需要用到的参数，表示遍历Scheme时忽略这些kinds。
然后调用api.NewDefaultRESTMapper()，importPrefix参数为："k8s.io/kubernetes/pkg/api"，
interfacesFor是一个接口。
路径：pkg/api/mapper.go
func NewDefaultRESTMapper(defaultGroupVersions []unversioned.GroupVersion, interfacesFunc meta.VersionInterfacesFunc,
importPathPrefix string, ignoredKinds, rootScoped sets.String) *meta.DefaultRESTMapper {
// 加入Scheme,并继续调用下面的接口
return NewDefaultRESTMapperFromScheme(defaultGroupVersions, interfacesFunc, importPathPrefix, ignoredKinds, rootScoped, Scheme)
}
func NewDefaultRESTMapperFromScheme(defaultGroupVersions []unversioned.GroupVersion, interfacesFunc meta.VersionInterfacesFunc,
importPathPrefix string, ignoredKinds, rootScoped sets.String, scheme *runtime.Scheme) *meta.DefaultRESTMapper {
// 初始化了一个DefaultRESTMapper对象
mapper := meta.NewDefaultRESTMapper(defaultGroupVersions, interfacesFunc)
// 根据输入的defaultGroupVersions,比如"/api/v1"，从Scheme中遍历所有的kinds
// 然后进行Add
for _, gv := range defaultGroupVersions {
for kind, oType := range scheme.KnownTypes(gv) {
gvk := gv.WithKind(kind)
// 过滤掉不属于"k8s.io/kubernetes/pkg/api"路径下的api，和ignoredKinds
if !strings.Contains(oType.PkgPath(), importPathPrefix) || ignoredKinds.Has(kind) {
continue
}
// 判断该kind是否有namespace属性
scope := meta.RESTScopeNamespace
if rootScoped.Has(kind) {
scope = meta.RESTScopeRoot
}
// 然后将该gvk加入到对应的组中
mapper.Add(gvk, scope)
}
}
return mapper
}再看看该接口，先创建了一个空的DefaultRESTMapper,然后根据"/api/v1"的groupVersion,遍历Scheme中所有的kinds，接着再调用mapper.Add(gvk, scope)去填充这个mapper，最后返回该mapper。
看下mapper.Add()的实现：
func (m *DefaultRESTMapper) Add(kind unversioned.GroupVersionKind, scope RESTScope) {
// resource还分为单数和复数
plural, singular := KindToResource(kind)
// 单数，复数相互转换
m.singularToPlural[singular] = plural
m.pluralToSingular[plural] = singular
// 根据单复数的resource找到对应的kind
m.resourceToKind[singular] = kind
m.resourceToKind[plural] = kind
// 根据kind找到对应的单复数resource
m.kindToPluralResource[kind] = plural
// kind到scope的转换
m.kindToScope[kind] = scope
}RESTMapper其实包含的是一种转换关系，resource到kind，kind到resource，kind到scope的转换。resource还分单数和复数。
kind和resource有什么区别呢？二者都是字符串，kind是通过Kind=reflector.TypeOf(&Pod{}).Elem().Name()进行取值，去的就是Pod这个结构体的名字。resource是通过plural, singular := KindToResource(kind)取值。singular是将Kind转换为小写字母，而plural是变为复数。
示例：以Pod为例，Kind是{Group:"", Version: "v1", Kind: "Pod"},那么singular是{Group:"", Version: "v1", Kind: "pod"},plural则是{Group："", Version："v1", Resource:"pods"}。
resource要区分单复数，是为了获取Pods信息。比如可以kubectl get pod，也可以kubectl get pods.
到这里RESTMapper也基本初始化完了，综合上面所有的初始化可以看到，其实主要用internal version和external versions填充Scheme，用external versions去填充GroupMeta以及其成员RESTMapper。
GroupMeta有啥作用呢？主要用于初始化APIGroupVersion。
API资源注册为restful api
之前所有的初始化都是为了这步做铺垫，上面还有一个APIGroupInfo和APIGroupVersion都没有进行介绍，这一节都会出现。
当API资源初始化完成以后，需要将这些API资源注册为restful api，用来接收用户的请求。
kube-apiServer使用了go-restful这套框架，里面主要包括三种对象：
Container: 一个Container包含多个WebService
WebService: 一个WebService包含多条route
Route: 一条route包含一个method(GET、POST、DELETE等)，一条具体的path(URL)以及一个响应的handler function。
API注册的入口函数有两个： m.InstallAPIs 和 m.InstallLegacyAPI。
文件路径：pkg/master/master.go
这两个函数分别用于注册"/api"和"/apis"的API,这里先拿InstallLegacyAPI进行介绍。
这些接口都是在config.Complete().New()函数中被调用：
restOptionsFactory := restOptionsFactory{
deleteCollectionWorkers: c.DeleteCollectionWorkers,
enableGarbageCollection: c.GenericConfig.EnableGarbageCollection,
storageFactory: c.StorageFactory,
}
// 判断是否使能了用于Watch的Cache
// 有无cache赋值的是不同的接口实现
// restOptionsFactory.storageDecorator：是一个各个资源的REST interface(CRUD)装饰者
// 后面调用NewStorage()时会用到该接口，并输出对应的CRUD接口及销毁接口。
// 可以参考pkg/registry/core/pod/etcd/etcd.go中的NewStorage()
// 其实这里有无cache的接口差异就在于：有cache的话，就提供操作cache的接口；无cache的话，就提供直接操作etcd的接口
if c.EnableWatchCache {
restOptionsFactory.storageDecorator = registry.StorageWithCacher
} else {
restOptionsFactory.storageDecorator = generic.UndecoratedStorage
}
// 判断/api/v1的group是否已经注册并enable，是的话再进行install
if c.GenericConfig.APIResourceConfigSource.AnyResourcesForVersionEnabled(apiv1.SchemeGroupVersion) {
// 该对象主要提供了一个NewLegacyRESTStorage()的接口
legacyRESTStorageProvider := corerest.LegacyRESTStorageProvider{
StorageFactory: c.StorageFactory,
ProxyTransport: c.ProxyTransport,
KubeletClientConfig: c.KubeletClientConfig,
EventTTL: c.EventTTL,
ServiceIPRange: c.ServiceIPRange,
ServiceNodePortRange: c.ServiceNodePortRange,
LoopbackClientConfig: c.GenericConfig.LoopbackClientConfig,
}
// 进行"/api/v1"的API安装
m.InstallLegacyAPI(c.Config, restOptionsFactory.NewFor, legacyRESTStorageProvider)
}继续查看m.InstallLegacyAPI()：
func (m *Master) InstallLegacyAPI(c *Config, restOptionsGetter genericapiserver.RESTOptionsGetter, legacyRESTStorageProvider corerest.LegacyRESTStorageProvider) {
// 该对象前面介绍过了，比较关键，需要深入查看
// 返回了RESTStorage和apiGroupInfo，都是重量级的成员
// 这些初始化也就在这个接口中
legacyRESTStorage, apiGroupInfo, err := legacyRESTStorageProvider.NewLegacyRESTStorage(restOptionsGetter)
if err != nil {
glog.Fatalf("Error building core storage: %v", err)
}
// 判断是否enable了controller,默认是true，这里跟主题关系不大，暂不深入
if c.EnableCoreControllers {
serviceClient := coreclient.NewForConfigOrDie(c.GenericConfig.LoopbackClientConfig)
bootstrapController := c.NewBootstrapController(legacyRESTStorage, serviceClient)
if err := m.GenericAPIServer.AddPostStartHook("bootstrap-controller", bootstrapController.PostStartHook); err != nil {
glog.Fatalf("Error registering PostStartHook %q: %v", "bootstrap-controller", err)
}
}
// install core Group's API
if err := m.GenericAPIServer.InstallLegacyAPIGroup(genericapiserver.DefaultLegacyAPIPrefix, &apiGroupInfo); err != nil {
glog.Fatalf("Error in registering group versions: %v", err)
}
}先看下创建APIGroupVersion和RESTStorage对象的接口NewLegacyRESTStorage().
路径：pkg/registry/core/rest/storage_core.go
func (c LegacyRESTStorageProvider) NewLegacyRESTStorage(restOptionsGetter genericapiserver.RESTOptionsGetter) (LegacyRESTStorage, genericapiserver.APIGroupInfo, error) {
// 初始化创建一个APIGroupVersion
apiGroupInfo := genericapiserver.APIGroupInfo{
// 该GroupMeta是从APIRegistrationManager初始化后的结构体获取
GroupMeta: *registered.GroupOrDie(api.GroupName),
VersionedResourcesStorageMap: map[string]map[string]rest.Storage{},
// 这个api.Scheme之前已经介绍过其初始化了
Scheme: api.Scheme,
ParameterCodec: api.ParameterCodec,
NegotiatedSerializer: api.Codecs,
SubresourceGroupVersionKind: map[string]unversioned.GroupVersionKind{},
}
// 判断下autoscaling是否已经注册并使能，是的话加入到apiGroupInfo.SubresourceGroupVersionKind
// key是该资源的path
if autoscalingGroupVersion := (unversioned.GroupVersion{Group: "autoscaling", Version: "v1"}); registered.IsEnabledVersion(autoscalingGroupVersion) {
apiGroupInfo.SubresourceGroupVersionKind["replicationcontrollers/scale"] = autoscalingGroupVersion.WithKind("Scale")
}
var podDisruptionClient policyclient.PodDisruptionBudgetsGetter
if policyGroupVersion := (unversioned.GroupVersion{Group: "policy", Version: "v1beta1"}); registered.IsEnabledVersion(policyGroupVersion) {
apiGroupInfo.SubresourceGroupVersionKind["pods/eviction"] = policyGroupVersion.WithKind("Eviction")
var err error
podDisruptionClient, err = policyclient.NewForConfig(c.LoopbackClientConfig)
if err != nil {
return LegacyRESTStorage{}, genericapiserver.APIGroupInfo{}, err
}
}
// 初始化一个LegacyRESTStorage对象
// 下面会进行各个接口的初始化，会有Node注册，IP申请，NodePort申请等等
restStorage := LegacyRESTStorage{}
// 创建各类Storage
podTemplateStorage := podtemplateetcd.NewREST(restOptionsGetter(api.Resource("podTemplates")))
eventStorage := eventetcd.NewREST(restOptionsGetter(api.Resource("events")), uint64(c.EventTTL.Seconds()))
limitRangeStorage := limitrangeetcd.NewREST(restOptionsGetter(api.Resource("limitRanges")))
resourceQuotaStorage, resourceQuotaStatusStorage := resourcequotaetcd.NewREST(restOptionsGetter(api.Resource("resourceQuotas")))
secretStorage := secretetcd.NewREST(restOptionsGetter(api.Resource("secrets")))
serviceAccountStorage := serviceaccountetcd.NewREST(restOptionsGetter(api.Resource("serviceAccounts")))
persistentVolumeStorage, persistentVolumeStatusStorage := pvetcd.NewREST(restOptionsGetter(api.Resource("persistentVolumes")))
persistentVolumeClaimStorage, persistentVolumeClaimStatusStorage := pvcetcd.NewREST(restOptionsGetter(api.Resource("persistentVolumeClaims")))
configMapStorage := configmapetcd.NewREST(restOptionsGetter(api.Resource("configMaps")))
namespaceStorage, namespaceStatusStorage, namespaceFinalizeStorage := namespaceetcd.NewREST(restOptionsGetter(api.Resource("namespaces")))
restStorage.NamespaceRegistry = namespace.NewRegistry(namespaceStorage)
endpointsStorage := endpointsetcd.NewREST(restOptionsGetter(api.Resource("endpoints")))
restStorage.EndpointRegistry = endpoint.NewRegistry(endpointsStorage)
nodeStorage, err := nodeetcd.NewStorage(restOptionsGetter(api.Resource("nodes")), c.KubeletClientConfig, c.ProxyTransport)
if err != nil {
return LegacyRESTStorage{}, genericapiserver.APIGroupInfo{}, err
}
restStorage.NodeRegistry = node.NewRegistry(nodeStorage.Node)
// 创建PodStorage
// api.Resource("pods")是合成了一个GroupResource的结构
podStorage := podetcd.NewStorage(
restOptionsGetter(api.Resource("pods")),
nodeStorage.KubeletConnectionInfo,
c.ProxyTransport,
podDisruptionClient,
)
serviceRESTStorage, serviceStatusStorage := serviceetcd.NewREST(restOptionsGetter(api.Resource("services")))
restStorage.ServiceRegistry = service.NewRegistry(serviceRESTStorage)
var serviceClusterIPRegistry rangeallocation.RangeRegistry
serviceClusterIPRange := c.ServiceIPRange
if serviceClusterIPRange.IP == nil {
return LegacyRESTStorage{}, genericapiserver.APIGroupInfo{}, fmt.Errorf("service clusterIPRange is missing")
}
serviceStorageConfig, err := c.StorageFactory.NewConfig(api.Resource("services"))
if err != nil {
return LegacyRESTStorage{}, genericapiserver.APIGroupInfo{}, err
}
ServiceClusterIPAllocator := ipallocator.NewAllocatorCIDRRange(&serviceClusterIPRange, func(max int, rangeSpec string) allocator.Interface {
mem := allocator.NewAllocationMap(max, rangeSpec)
// TODO etcdallocator package to return a storage interface via the storageFactory
etcd := etcdallocator.NewEtcd(mem, "/ranges/serviceips", api.Resource("serviceipallocations"), serviceStorageConfig)
serviceClusterIPRegistry = etcd
return etcd
})
restStorage.ServiceClusterIPAllocator = serviceClusterIPRegistry
var serviceNodePortRegistry rangeallocation.RangeRegistry
ServiceNodePortAllocator := portallocator.NewPortAllocatorCustom(c.ServiceNodePortRange, func(max int, rangeSpec string) allocator.Interface {
mem := allocator.NewAllocationMap(max, rangeSpec)
// TODO etcdallocator package to return a storage interface via the storageFactory
etcd := etcdallocator.NewEtcd(mem, "/ranges/servicenodeports", api.Resource("servicenodeportallocations"), serviceStorageConfig)
serviceNodePortRegistry = etcd
return etcd
})
restStorage.ServiceNodePortAllocator = serviceNodePortRegistry
controllerStorage := controlleretcd.NewStorage(restOptionsGetter(api.Resource("replicationControllers")))
serviceRest := service.NewStorage(restStorage.ServiceRegistry, restStorage.EndpointRegistry, ServiceClusterIPAllocator, ServiceNodePortAllocator, c.ProxyTransport)
// 初始化了一个restStorage的map，然后赋值给APIGroupInfo.VersionedResourcesStorageMap["v1"]
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.Binding,
"podTemplates": podTemplateStorage,
"replicationControllers": controllerStorage.Controller,
"replicationControllers/status": controllerStorage.Status,
"services": serviceRest.Service,
"services/proxy": serviceRest.Proxy,
"services/status": serviceStatusStorage,
"endpoints": endpointsStorage,
"nodes": nodeStorage.Node,
"nodes/status": nodeStorage.Status,
"nodes/proxy": nodeStorage.Proxy,
"events": eventStorage,
"limitRanges": limitRangeStorage,
"resourceQuotas": resourceQuotaStorage,
"resourceQuotas/status": resourceQuotaStatusStorage,
"namespaces": namespaceStorage,
"namespaces/status": namespaceStatusStorage,
"namespaces/finalize": namespaceFinalizeStorage,
"secrets": secretStorage,
"serviceAccounts": serviceAccountStorage,
"persistentVolumes": persistentVolumeStorage,
"persistentVolumes/status": persistentVolumeStatusStorage,
"persistentVolumeClaims": persistentVolumeClaimStorage,
"persistentVolumeClaims/status": persistentVolumeClaimStatusStorage,
"configMaps": configMapStorage,
"componentStatuses": componentstatus.NewStorage(componentStatusStorage{c.StorageFactory}.serversToValidate),
}
if registered.IsEnabledVersion(unversioned.GroupVersion{Group: "autoscaling", Version: "v1"}) {
restStorageMap["replicationControllers/scale"] = controllerStorage.Scale
}
if registered.IsEnabledVersion(unversioned.GroupVersion{Group: "policy", Version: "v1beta1"}) {
restStorageMap["pods/eviction"] = podStorage.Eviction
}
// 将上面的restStorageMap赋值给v1
apiGroupInfo.VersionedResourcesStorageMap["v1"] = restStorageMap
return restStorage, apiGroupInfo, nil
}看完这个接口后，我们继续回到前面，看下m.GenericAPIServer.InstallLegacyAPIGroup()接口：
路径：pkg/genericapiserver/genericapiserver.go
func (s *GenericAPIServer) InstallLegacyAPIGroup(apiPrefix string, apiGroupInfo *APIGroupInfo) error {
// 判断前缀参数是否正确
if !s.legacyAPIGroupPrefixes.Has(apiPrefix) {
return fmt.Errorf("%q is not in the allowed legacy API prefixes: %v", apiPrefix, s.legacyAPIGroupPrefixes.List())
}
// 关键接口，真正install API
if err := s.installAPIResources(apiPrefix, apiGroupInfo); err != nil {
return err
}
// 获取了该Group下所有的version信息
// 应该用于发现当前的所有版本信息
apiVersions := []string{}
for _, groupVersion := range apiGroupInfo.GroupMeta.GroupVersions {
apiVersions = append(apiVersions, groupVersion.Version)
}
// Install the version handler.
// Add a handler at /<apiPrefix> to enumerate the supported api versions.
apiserver.AddApiWebService(s.Serializer, s.HandlerContainer.Container, apiPrefix, func(req *restful.Request) *unversioned.APIVersions {
clientIP := utilnet.GetClientIP(req.Request)
apiVersionsForDiscovery := unversioned.APIVersions{
ServerAddressByClientCIDRs: s.discoveryAddresses.ServerAddressByClientCIDRs(clientIP),
Versions: apiVersions,
}
return &apiVersionsForDiscovery
})
return nil
}那我们继续进入关键接口s.installAPIResources(apiPrefix, apiGroupInfo):
func (s *GenericAPIServer) installAPIResources(apiPrefix string, apiGroupInfo *APIGroupInfo) error {
// 遍历该Group下的所有GroupVersons
for _, groupVersion := range apiGroupInfo.GroupMeta.GroupVersions {
// 创建APIGroupVersion
apiGroupVersion, err := s.getAPIGroupVersion(apiGroupInfo, groupVersion, apiPrefix)
if err != nil {
return err
}
if apiGroupInfo.OptionsExternalVersion != nil {
apiGroupVersion.OptionsExternalVersion = apiGroupInfo.OptionsExternalVersion
}
// 根据之前创建的APIGroupVersion,然后安装restful API
// 该s.HandlerContainer.Container就是go-restful的Container
if err := apiGroupVersion.InstallREST(s.HandlerContainer.Container); err != nil {
return fmt.Errorf("Unable to setup API %v: %v", apiGroupInfo, err)
}
}
return nil
}
func (s *GenericAPIServer) getAPIGroupVersion(apiGroupInfo *APIGroupInfo, groupVersion unversioned.GroupVersion, apiPrefix string) (*apiserver.APIGroupVersion, error) {
storage := make(map[string]rest.Storage)
// 如果是核心组的话，Version为"v1",该VersionedResourcesStorageMap的初始化要看
// 之前的NewLegacyRESTStorage()接口，在该接口中进行的初始化
// 遍历所有的ResourcesStorage，并赋值给storage
for k, v := range apiGroupInfo.VersionedResourcesStorageMap[groupVersion.Version] {
storage[strings.ToLower(k)] = v
}
// 创建APIGroupVersion
version, err := s.newAPIGroupVersion(apiGroupInfo, groupVersion)
// 设置Prefix, 核心组的话是"/api"
version.Root = apiPrefix
version.Storage = storage
return version, err
}到这里从API资源到restful API,就已经注册完成了。
至于apiGroupVersion.InstallREST()接口，我们这里先简单介绍，后面会另起一篇文章结合go-restful进行介绍。
InstallREST()接口路径：pkg/apiserver/apiserver.go
func (g *APIGroupVersion) InstallREST(container *restful.Container) error {
installer := g.newInstaller()
ws := installer.NewWebService()
apiResources, registrationErrors := installer.Install(ws)
lister := g.ResourceLister
if lister == nil {
lister = staticLister{apiResources}
}
AddSupportedResourcesWebService(g.Serializer, ws, g.GroupVersion, lister)
container.Add(ws)
return utilerrors.NewAggregate(registrationErrors)
}
func (a *APIInstaller) Install(ws *restful.WebService) (apiResources []unversioned.APIResource, errors []error) {
errors = make([]error, 0)
proxyHandler := (&ProxyHandler{
prefix: a.prefix + "/proxy/",
storage: a.group.Storage,
serializer: a.group.Serializer,
mapper: a.group.Context,
})
// Register the paths in a deterministic (sorted) order to get a deterministic swagger spec.
paths := make([]string, len(a.group.Storage))
var i int = 0
for path := range a.group.Storage {
paths[i] = path
i++
}
sort.Strings(paths)
for _, path := range paths {
// 该接口是关键，最终将一个rest.Storage对象转换成实际的restful api，比如getter、lister等处理函数，并将实际的URL关联起来
apiResource, err := a.registerResourceHandlers(path, a.group.Storage[path], ws, proxyHandler)
if err != nil {
errors = append(errors, fmt.Errorf("error in registering resource: %s, %v", path, err))
}
if apiResource != nil {
apiResources = append(apiResources, *apiResource)
}
}
return apiResources, errors
}在这个注册的过程中，InstallREST最终调用了registerResourceHandlers()接口，该接口最终会把一个rest.Storage对象转换成实际的getter、lister等处理函数，并和实际的URL关联起来。
用户参数配置
runtime-config： 用于enable/disable extensions group。默认的情况下DaemonSets、Deployments、HorizontalPodAutoscalers、Ingress、Jobs和ReplicaSets是使能的,还有v1下的默认都是使能的。另外的功能就可以通过该配置进行设置. 例如：disable deployments： --runtime-config=extensions/v1beta1/deployments=false.
参考资料
1.api-group.md: https://github.com/kubernetes...
有疑问加站长微信联系（非本文作者）
