【K8s源码品读】007：Phase 1 - kube-apiserver - Pod数据的保存

// podStrategy 是封装了 Pod 的各类动作，这里我们先关注create这个操作
type podStrategy struct {
 runtime.ObjectTyper
 names.NameGenerator
}

// podStrategy 的接口
type RESTCreateStrategy interface {
 runtime.ObjectTyper
 names.NameGenerator
  // 是否属于当前的 namespace
 NamespaceScoped() bool
  // 准备创建前的检查
 PrepareForCreate(ctx context.Context, obj runtime.Object)
  // 验证资源对象
 Validate(ctx context.Context, obj runtime.Object) field.ErrorList
  // 规范化
 Canonicalize(obj runtime.Object)
}

// 完成了检查，我们就要保存数据了

// PodStorage 是 Pod 存储的实现，里面包含了多个存储的定义
type PodStorage struct {
  // REST implements a RESTStorage for pods
 Pod                 *REST
  // BindingREST implements the REST endpoint for binding pods to nodes when etcd is in use.
 Binding             *BindingREST
  // LegacyBindingREST implements the REST endpoint for binding pods to nodes when etcd is in use.
 LegacyBinding       *LegacyBindingREST
 Eviction            *EvictionREST
  // StatusREST implements the REST endpoint for changing the status of a pod.
 Status              *StatusREST
  // EphemeralContainersREST implements the REST endpoint for adding EphemeralContainers
 EphemeralContainers *EphemeralContainersREST
 Log                 *podrest.LogREST
 Proxy               *podrest.ProxyREST
 Exec                *podrest.ExecREST
 Attach              *podrest.AttachREST
 PortForward         *podrest.PortForwardREST
}

/*
从上一节的map关系中，保存在REST中
restStorageMap := map[string]rest.Storage{
  "pods":             podStorage.Pod,
}
*/
type REST struct {
 *genericregistry.Store
 proxyTransport http.RoundTripper
}

// Store是一个通用的数据结构
type Store struct {
 // Storage定义
 Storage DryRunnableStorage
}

// DryRunnableStorage中的Storage是一个Interface
type DryRunnableStorage struct {
 Storage storage.Interface
 Codec   runtime.Codec
}

func (s *DryRunnableStorage) Create(ctx context.Context, key string, obj, out runtime.Object, ttl uint64, dryRun bool) error {
 if dryRun {
  if err := s.Storage.Get(ctx, key, storage.GetOptions{}, out); err == nil {
   return storage.NewKeyExistsError(key, 0)
  }
  return s.copyInto(obj, out)
 }
  // 这里，就是Create的真正调用
 return s.Storage.Create(ctx, key, obj, out, ttl)
}

// Storage Interface 的定义，包括基本的增删改查，以及watch等等进阶操作
type Interface interface {
 Versioner() Versioner
 Create(ctx context.Context, key string, obj, out runtime.Object, ttl uint64) error
 Delete(ctx context.Context, key string, out runtime.Object, preconditions *Preconditions, validateDeletion ValidateObjectFunc) error
 Watch(ctx context.Context, key string, opts ListOptions) (watch.Interface, error)
 WatchList(ctx context.Context, key string, opts ListOptions) (watch.Interface, error)
 Get(ctx context.Context, key string, opts GetOptions, objPtr runtime.Object) error
 GetToList(ctx context.Context, key string, opts ListOptions, listObj runtime.Object) error
 List(ctx context.Context, key string, opts ListOptions, listObj runtime.Object) error
 GuaranteedUpdate(
  ctx context.Context, key string, ptrToType runtime.Object, ignoreNotFound bool,
  precondtions *Preconditions, tryUpdate UpdateFunc, suggestion ...runtime.Object) error
 Count(key string) (int64, error)
}

func NewRawStorage(config *storagebackend.Config) (storage.Interface, factory.DestroyFunc, error) {
 return factory.Create(*config)
}

func Create(c storagebackend.Config) (storage.Interface, DestroyFunc, error) {
 switch c.Type {
  // 已经不支持etcd2
 case "etcd2":
  return nil, nil, fmt.Errorf("%v is no longer a supported storage backend", c.Type)
  // 默认为etcd3版本
 case storagebackend.StorageTypeUnset, storagebackend.StorageTypeETCD3:
  return newETCD3Storage(c)
 default:
  return nil, nil, fmt.Errorf("unknown storage type: %s", c.Type)
 }
}