manager

type BaseContextFunc func() context.Context

type LeaderElectionRunnable interface {
	// NeedLeaderElection returns true if the Runnable needs to be run in the leader election mode.
	// e.g. controllers need to be run in leader election mode, while webhook server doesn't.
	NeedLeaderElection() bool
}

type Manager interface {
	// Cluster holds a variety of methods to interact with a cluster.
	cluster.Cluster

	// Add will set requested dependencies on the component, and cause the component to be
	// started when Start is called.
	// Depending on if a Runnable implements LeaderElectionRunnable interface, a Runnable can be run in either
	// non-leaderelection mode (always running) or leader election mode (managed by leader election if enabled).
	Add(Runnable) error

	// Elected is closed when this manager is elected leader of a group of
	// managers, either because it won a leader election or because no leader
	// election was configured.
	Elected() <-chan struct{}

	// AddMetricsServerExtraHandler adds an extra handler served on path to the http server that serves metrics.
	// Might be useful to register some diagnostic endpoints e.g. pprof.
	//
	// Note that these endpoints are meant to be sensitive and shouldn't be exposed publicly.
	//
	// If the simple path -> handler mapping offered here is not enough,
	// a new http server/listener should be added as Runnable to the manager via Add method.
	AddMetricsServerExtraHandler(path string, handler http.Handler) error

	// AddHealthzCheck allows you to add Healthz checker
	AddHealthzCheck(name string, check healthz.Checker) error

	// AddReadyzCheck allows you to add Readyz checker
	AddReadyzCheck(name string, check healthz.Checker) error

	// Start starts all registered Controllers and blocks until the context is cancelled.
	// Returns an error if there is an error starting any controller.
	//
	// If LeaderElection is used, the binary must be exited immediately after this returns,
	// otherwise components that need leader election might continue to run after the leader
	// lock was lost.
	Start(ctx context.Context) error

	// GetWebhookServer returns a webhook.Server
	GetWebhookServer() webhook.Server

	// GetLogger returns this manager's logger.
	GetLogger() logr.Logger

	// GetControllerOptions returns controller global configuration options.
	GetControllerOptions() config.Controller
}

type Options struct {
	// Scheme is the scheme used to resolve runtime.Objects to GroupVersionKinds / Resources.
	// Defaults to the kubernetes/client-go scheme.Scheme, but it's almost always better
	// to pass your own scheme in. See the documentation in pkg/scheme for more information.
	//
	// If set, the Scheme will be used to create the default Client and Cache.
	Scheme *runtime.Scheme

	// MapperProvider provides the rest mapper used to map go types to Kubernetes APIs.
	//
	// If set, the RESTMapper returned by this function is used to create the RESTMapper
	// used by the Client and Cache.
	MapperProvider func(c *rest.Config, httpClient *http.Client) (meta.RESTMapper, error)

	// Cache is the cache.Options that will be used to create the default Cache.
	// By default, the cache will watch and list requested objects in all namespaces.
	Cache cache.Options

	// NewCache is the function that will create the cache to be used
	// by the manager. If not set this will use the default new cache function.
	//
	// When using a custom NewCache, the Cache options will be passed to the
	// NewCache function.
	//
	// NOTE: LOW LEVEL PRIMITIVE!
	// Only use a custom NewCache if you know what you are doing.
	NewCache cache.NewCacheFunc

	// Client is the client.Options that will be used to create the default Client.
	// By default, the client will use the cache for reads and direct calls for writes.
	Client client.Options

	// NewClient is the func that creates the client to be used by the manager.
	// If not set this will create a Client backed by a Cache for read operations
	// and a direct Client for write operations.
	//
	// When using a custom NewClient, the Client options will be passed to the
	// NewClient function.
	//
	// NOTE: LOW LEVEL PRIMITIVE!
	// Only use a custom NewClient if you know what you are doing.
	NewClient client.NewClientFunc

	// Logger is the logger that should be used by this manager.
	// If none is set, it defaults to log.Log global logger.
	Logger logr.Logger

	// LeaderElection determines whether or not to use leader election when
	// starting the manager.
	LeaderElection bool

	// LeaderElectionResourceLock determines which resource lock to use for leader election,
	// defaults to "leases". Change this value only if you know what you are doing.
	//
	// If you are using `configmaps`/`endpoints` resource lock and want to migrate to "leases",
	// you might do so by migrating to the respective multilock first ("configmapsleases" or "endpointsleases"),
	// which will acquire a leader lock on both resources.
	// After all your users have migrated to the multilock, you can go ahead and migrate to "leases".
	// Please also keep in mind, that users might skip versions of your controller.
	//
	// Note: before controller-runtime version v0.7, it was set to "configmaps".
	// And from v0.7 to v0.11, the default was "configmapsleases", which was
	// used to migrate from configmaps to leases.
	// Since the default was "configmapsleases" for over a year, spanning five minor releases,
	// any actively maintained operators are very likely to have a released version that uses
	// "configmapsleases". Therefore defaulting to "leases" should be safe since v0.12.
	//
	// So, what do you have to do when you are updating your controller-runtime dependency
	// from a lower version to v0.12 or newer?
	// - If your operator matches at least one of these conditions:
	//   - the LeaderElectionResourceLock in your operator has already been explicitly set to "leases"
	//   - the old controller-runtime version is between v0.7.0 and v0.11.x and the
	//     LeaderElectionResourceLock wasn't set or was set to "leases"/"configmapsleases"/"endpointsleases"
	//   feel free to update controller-runtime to v0.12 or newer.
	// - Otherwise, you may have to take these steps:
	//   1. update controller-runtime to v0.12 or newer in your go.mod
	//   2. set LeaderElectionResourceLock to "configmapsleases" (or "endpointsleases")
	//   3. package your operator and upgrade it in all your clusters
	//   4. only if you have finished 3, you can remove the LeaderElectionResourceLock to use the default "leases"
	// Otherwise, your operator might end up with multiple running instances that
	// each acquired leadership through different resource locks during upgrades and thus
	// act on the same resources concurrently.
	LeaderElectionResourceLock string

	// LeaderElectionNamespace determines the namespace in which the leader
	// election resource will be created.
	LeaderElectionNamespace string

	// LeaderElectionID determines the name of the resource that leader election
	// will use for holding the leader lock.
	LeaderElectionID string

	// LeaderElectionConfig can be specified to override the default configuration
	// that is used to build the leader election client.
	LeaderElectionConfig *rest.Config

	// LeaderElectionReleaseOnCancel defines if the leader should step down voluntarily
	// when the Manager ends. This requires the binary to immediately end when the
	// Manager is stopped, otherwise this setting is unsafe. Setting this significantly
	// speeds up voluntary leader transitions as the new leader doesn't have to wait
	// LeaseDuration time first.
	LeaderElectionReleaseOnCancel bool

	// LeaderElectionLabels allows a controller to supplement all leader election api calls with a set of custom labels based on
	// the replica attempting to acquire leader status.
	LeaderElectionLabels map[string]string

	// LeaderElectionResourceLockInterface allows to provide a custom resourcelock.Interface that was created outside
	// of the controller-runtime. If this value is set the options LeaderElectionID, LeaderElectionNamespace,
	//  LeaderElectionResourceLock, LeaseDuration, RenewDeadline, RetryPeriod and LeaderElectionLeases will be ignored.
	// This can be useful if you want to use a locking mechanism that is currently not supported, like a MultiLock across
	// two Kubernetes clusters.
	LeaderElectionResourceLockInterface resourcelock.Interface

	// LeaseDuration is the duration that non-leader candidates will
	// wait to force acquire leadership. This is measured against time of
	// last observed ack. Default is 15 seconds.
	LeaseDuration *time.Duration

	// RenewDeadline is the duration that the acting controlplane will retry
	// refreshing leadership before giving up. Default is 10 seconds.
	RenewDeadline *time.Duration

	// RetryPeriod is the duration the LeaderElector clients should wait
	// between tries of actions. Default is 2 seconds.
	RetryPeriod *time.Duration

	// Metrics are the metricsserver.Options that will be used to create the metricsserver.Server.
	Metrics metricsserver.Options

	// HealthProbeBindAddress is the TCP address that the controller should bind to
	// for serving health probes
	// It can be set to "0" or "" to disable serving the health probe.
	HealthProbeBindAddress string

	// Readiness probe endpoint name, defaults to "readyz"
	ReadinessEndpointName string

	// Liveness probe endpoint name, defaults to "healthz"
	LivenessEndpointName string

	// PprofBindAddress is the TCP address that the controller should bind to
	// for serving pprof.
	// It can be set to "" or "0" to disable the pprof serving.
	// Since pprof may contain sensitive information, make sure to protect it
	// before exposing it to public.
	PprofBindAddress string

	// WebhookServer is an externally configured webhook.Server. By default,
	// a Manager will create a server via webhook.NewServer with default settings.
	// If this is set, the Manager will use this server instead.
	WebhookServer webhook.Server

	// BaseContext is the function that provides Context values to Runnables
	// managed by the Manager. If a BaseContext function isn't provided, Runnables
	// will receive a new Background Context instead.
	BaseContext BaseContextFunc

	// EventBroadcaster records Events emitted by the manager and sends them to the Kubernetes API
	// Use this to customize the event correlator and spam filter
	//
	// Deprecated: using this may cause goroutine leaks if the lifetime of your manager or controllers
	// is shorter than the lifetime of your process.
	EventBroadcaster record.EventBroadcaster

	// GracefulShutdownTimeout is the duration given to runnable to stop before the manager actually returns on stop.
	// To disable graceful shutdown, set to time.Duration(0)
	// To use graceful shutdown without timeout, set to a negative duration, e.G. time.Duration(-1)
	// The graceful shutdown is skipped for safety reasons in case the leader election lease is lost.
	GracefulShutdownTimeout *time.Duration

	// Controller contains global configuration options for controllers
	// registered within this manager.
	// +optional
	Controller config.Controller
	// contains filtered or unexported fields
}

type Runnable interface {
	// Start starts running the component.  The component will stop running
	// when the context is closed. Start blocks until the context is closed or
	// an error occurs.
	Start(context.Context) error
}

type RunnableFunc func(context.Context) error

type Server struct {
	// Name is an optional string that describes the purpose of the server. It is used in logs to distinguish
	// among multiple servers.
	Name string

	// Server is the HTTP server to run. It is required.
	Server *http.Server

	// Listener is an optional listener to use. If not set, the server start a listener using the server.Addr.
	// Using a listener is useful when the port reservation needs to happen in advance of this runnable starting.
	Listener net.Listener

	// OnlyServeWhenLeader is an optional bool that indicates that the server should only be started when the manager is the leader.
	OnlyServeWhenLeader bool

	// ShutdownTimeout is an optional duration that indicates how long to wait for the server to shutdown gracefully. If not set,
	// the server will wait indefinitely for all connections to close.
	ShutdownTimeout *time.Duration
}