watch

Documentation

Index

• type Accessors
• type Client
• type Config
• type HandlerFuncs
• type Index
• type IndexedStore
  • func NewIndexedStore[T any, I Index[T]](store *Store[T], index I) IndexedStore[T, I]
  • func (w IndexedStore[T, I]) GetIndexed(f func(I) (*T, bool)) (obj *T, ok bool)
  • func (w IndexedStore[T, I]) ListIndexed(f func(I) []*T) (list []*T)
  • func (w IndexedStore[T, I]) WithIndex(f func(I))
• type InitMode
• type Metrics
  • func NewMetrics(prefix string) Metrics
  • func (m *Metrics) MustRegister(reg *prometheus.Registry)
• type MetricsConfig
• type NameIndex
  • func NewNameIndex[T any]() *NameIndex[T]
  • func (i *NameIndex[T]) Add(obj *T)
  • func (i *NameIndex[T]) Delete(obj *T)
  • func (i *NameIndex[T]) Get(namespace string, name string) (obj *T, ok bool)
  • func (i *NameIndex[T]) Update(oldObj, newObj *T)
• type Object
• type Store
  • func Watch[C Client[L], L metav1.ListMetaAccessor, T any, P Object[T]](ctx context.Context, client C, config Config, accessors Accessors[L, T], ...) (*Store[T], error)
  • func (w *Store[T]) Items() []*T
  • func (w *Store[T]) Relist() <-chan struct{}
  • func (w *Store[T]) Stop()
  • func (w *Store[T]) Stopped() bool

Types

type Accessors

type Accessors[L any, T any] struct {
	Items func(L) []T
}

Accessors provides the "glue" functions for Watch to go from a list L (returned by the client's List) to the underlying slice of items []T

type Client

type Client[L any] interface {
	List(context.Context, metav1.ListOptions) (L, error)
	Watch(context.Context, metav1.ListOptions) (watch.Interface, error)
}

Client is implemented by the specific interfaces of kubernetes clients, like `Clientset.CoreV1().Pods(namespace)` or `..Nodes()`

This interface should be *already implemented* by whatever the correct client is.

type Config

type Config struct {
	// LogName is the name of the watcher for use in logs
	LogName string

	// Metrics will be used by the Watch call to report some information about its internal
	// operations
	//
	// Refer to the Metrics and MetricsConfig types for more information.
	Metrics MetricsConfig

	// RetryRelistAfter gives a retry interval when a re-list fails. If left nil, then Watch will
	// not retry.
	RetryRelistAfter *util.TimeRange
	// RetryWatchAfter gives a retry interval when a non-initial watch fails. If left nil, then
	// Watch will not retry.
	RetryWatchAfter *util.TimeRange
}

Config is the miscellaneous configuration used by Watch

type HandlerFuncs

type HandlerFuncs[P any] struct {
	AddFunc    func(obj P, preexisting bool)
	UpdateFunc func(oldObj P, newObj P)
	DeleteFunc func(obj P, mayBeStale bool)
}

HandlerFuncs provides the set of callbacks to use for events from Watch

type Index

type Index[T any] interface {
	Add(obj *T)
	Update(oldObj, newObj *T)
	Delete(obj *T)
}

Index represents types that provide some kind of additional index on top of the base listing

Indexing is functionally implemented in the same way that WatchHandlerFuncs is, with the main difference being that more things are done for you with WatchIndexes. In particular, indexes can be added and removed after the Watch has already started, and the locking behavior is explicit.

type IndexedStore

type IndexedStore[T any, I Index[T]] struct {
	*Store[T]
	// contains filtered or unexported fields
}

IndexedStore represents a WatchStore, wrapped with a privileged WatchIndex that can be used to efficiently answer queries.

func NewIndexedStore

func NewIndexedStore[T any, I Index[T]](store *Store[T], index I) IndexedStore[T, I]

NewIndexedStore creates a new IndexedWatchStore from the WatchStore and the index to use.

Note: the index type is assumed to have reference semantics; i.e. any shallow copy of the value will affect any other shallow copy.

For more information, refer to IndexedWatchStore.

func (IndexedStore[T, I]) GetIndexed

func (w IndexedStore[T, I]) GetIndexed(f func(I) (*T, bool)) (obj *T, ok bool)

func (IndexedStore[T, I]) ListIndexed

func (w IndexedStore[T, I]) ListIndexed(f func(I) []*T) (list []*T)

func (IndexedStore[T, I]) WithIndex

func (w IndexedStore[T, I]) WithIndex(f func(I))

WithIndex calls a function with the current state of the index, locking the WatchStore around it.

It is almost guaranteed to be an error to indirectly return the index with this function.

type InitMode

type InitMode string

InitMode dictates the behavior of Watch with respect to any initial calls to handlers.AddFunc before returning

If set to InitWatchModeSync, then AddFunc will be called while processing the initial listing, meaning that the returned WatchStore is guaranteed contain the state of the cluster (although it may update before any access).

Otherwise, if set to InitWatchModeDefer, then AddFunc will not be called until after Watch returns. Correspondingly, the WatchStore will not update until then either.

const (
	InitModeSync  InitMode = "sync"
	InitModeDefer InitMode = "defer"
)

type Metrics

type Metrics struct {
	// contains filtered or unexported fields
}

Metrics holds some common prometheus collectors that are used by Watch

The metrics used are:

- client_calls_total (number of calls to k8s client.{Watch,List}, labeled by method) - relist_requests_total (number of "relist" requests from the Store) - events_total (number of K8s watch.Events that have occurred, including errors) - errors_total (number of errors, either error events or re-List errors, labeled by source: ["List", "Watch", "Watch.Event"]) - alive_current (1 iff the watcher is currently running or failing, else 0) - failing_current (1 iff the watcher's last request failed *and* it's waiting to retry, else 0)

Prefixes are typically of the form "COMPONENT_watchers" (e.g. "autoscaling_agent_watchers"). Separate reporting per call to Watch is automatically done with the "watcher_instance" label attached to the metrics, using MetricsConfig.

A brief note about "alive" and "failing": Reading from a pair of collectors is fundamentally racy. It may be possible to temporarily view "failing" but not "alive".

func NewMetrics

func NewMetrics(prefix string) Metrics

NewMetrics creates a new set of metrics for one or many Watch calls

All metrics' names will be prefixed with the provided string.

func (*Metrics) MustRegister

func (m *Metrics) MustRegister(reg *prometheus.Registry)

MustRegister registers all the collectors in the Metrics

type MetricsConfig

type MetricsConfig struct {
	Metrics
	// Instance provides the value of the "watcher_instance" label that will be applied to all
	// metrics collected for the Watch call
	Instance string
}

type NameIndex

type NameIndex[T any] struct {
	// contains filtered or unexported fields
}

NameIndex is a WatchIndex that provides efficient lookup for a value with a particular name

func NewNameIndex

func NewNameIndex[T any]() *NameIndex[T]

func (*NameIndex[T]) Add

func (i *NameIndex[T]) Add(obj *T)

func (*NameIndex[T]) Delete

func (i *NameIndex[T]) Delete(obj *T)

func (*NameIndex[T]) Get

func (i *NameIndex[T]) Get(namespace string, name string) (obj *T, ok bool)

func (*NameIndex[T]) Update

func (i *NameIndex[T]) Update(oldObj, newObj *T)

type Object

type Object[T any] interface {
	~*T
	runtime.Object
	metav1.ObjectMetaAccessor
}

Object is implemented by pointers to T, where T is typically the resource that we're actually watching.

Example implementors: *corev1.Pod, *corev1.Node

type Store

type Store[T any] struct {
	// contains filtered or unexported fields
}

Store provides an interface for getting information about a list of Ts using the event listener from a previous call to Watch

func Watch

func Watch[C Client[L], L metav1.ListMetaAccessor, T any, P Object[T]](
	ctx context.Context,
	client C,
	config Config,
	accessors Accessors[L, T],
	mode InitMode,
	opts metav1.ListOptions,
	handlers HandlerFuncs[P],
) (*Store[T], error)

Watch starts a goroutine for watching events, using the provided WatchHandlerFuncs as the callbacks for each type of event.

The type C is the kubernetes client we use to get the objects, L representing a list of these, T representing the object type, and P as a pointer to T.

func (*Store[T]) Items

func (w *Store[T]) Items() []*T

func (*Store[T]) Relist

func (w *Store[T]) Relist() <-chan struct{}

Relist triggers re-listing the WatchStore, returning a channel that will be closed once the re-list is complete

func (*Store[T]) Stop

func (w *Store[T]) Stop()

func (*Store[T]) Stopped

func (w *Store[T]) Stopped() bool