const (
JitterFactor = 1.2
)
func RunOrDie(ctx context.Context, lec LeaderElectionConfig)
RunOrDie starts a client with the provided config or panics if the config fails to validate. RunOrDie blocks until leader election loop is stopped by ctx or it has stopped holding the leader lease
func SetProvider(metricsProvider MetricsProvider)
SetProvider sets the metrics provider for all subsequently created work queues. Only the first call has an effect.
HealthzAdaptor associates the /healthz endpoint with the LeaderElection object. It helps deal with the /healthz endpoint being set up prior to the LeaderElection. This contains the code needed to act as an adaptor between the leader election code the health check code. It allows us to provide health status about the leader election. Most specifically about if the leader has failed to renew without exiting the process. In that case we should report not healthy and rely on the kubelet to take down the process.
type HealthzAdaptor struct {
// contains filtered or unexported fields
}
func NewLeaderHealthzAdaptor(timeout time.Duration) *HealthzAdaptor
NewLeaderHealthzAdaptor creates a basic healthz adaptor to monitor a leader election. timeout determines the time beyond the lease expiry to be allowed for timeout. checks within the timeout period after the lease expires will still return healthy.
func (l *HealthzAdaptor) Check(req *http.Request) error
Check is called by the healthz endpoint handler. It fails (returns an error) if we own the lease but had not been able to renew it.
func (l *HealthzAdaptor) Name() string
Name returns the name of the health check we are implementing.
func (l *HealthzAdaptor) SetLeaderElection(le *LeaderElector)
SetLeaderElection ties a leader election object to a HealthzAdaptor
LeaderCallbacks are callbacks that are triggered during certain lifecycle events of the LeaderElector. These are invoked asynchronously.
possible future callbacks:
type LeaderCallbacks struct {
// OnStartedLeading is called when a LeaderElector client starts leading
OnStartedLeading func(context.Context)
// OnStoppedLeading is called when a LeaderElector client stops leading
OnStoppedLeading func()
// OnNewLeader is called when the client observes a leader that is
// not the previously observed leader. This includes the first observed
// leader when the client starts.
OnNewLeader func(identity string)
}
type LeaderElectionConfig struct {
// Lock is the resource that will be used for locking
Lock rl.Interface
// LeaseDuration is the duration that non-leader candidates will
// wait to force acquire leadership. This is measured against time of
// last observed ack.
//
// A client needs to wait a full LeaseDuration without observing a change to
// the record before it can attempt to take over. When all clients are
// shutdown and a new set of clients are started with different names against
// the same leader record, they must wait the full LeaseDuration before
// attempting to acquire the lease. Thus LeaseDuration should be as short as
// possible (within your tolerance for clock skew rate) to avoid a possible
// long waits in the scenario.
//
// Core clients default this value to 15 seconds.
LeaseDuration time.Duration
// RenewDeadline is the duration that the acting master will retry
// refreshing leadership before giving up.
//
// Core clients default this value to 10 seconds.
RenewDeadline time.Duration
// RetryPeriod is the duration the LeaderElector clients should wait
// between tries of actions.
//
// Core clients default this value to 2 seconds.
RetryPeriod time.Duration
// Callbacks are callbacks that are triggered during certain lifecycle
// events of the LeaderElector
Callbacks LeaderCallbacks
// WatchDog is the associated health checker
// WatchDog may be null if it's not needed/configured.
WatchDog *HealthzAdaptor
// ReleaseOnCancel should be set true if the lock should be released
// when the run context is cancelled. If you set this to true, you must
// ensure all code guarded by this lease has successfully completed
// prior to cancelling the context, or you may have two processes
// simultaneously acting on the critical path.
ReleaseOnCancel bool
// Name is the name of the resource lock for debugging
Name string
}
LeaderElector is a leader election client.
type LeaderElector struct {
// contains filtered or unexported fields
}
func NewLeaderElector(lec LeaderElectionConfig) (*LeaderElector, error)
NewLeaderElector creates a LeaderElector from a LeaderElectionConfig
func (le *LeaderElector) Check(maxTolerableExpiredLease time.Duration) error
Check will determine if the current lease is expired by more than timeout.
func (le *LeaderElector) GetLeader() string
GetLeader returns the identity of the last observed leader or returns the empty string if no leader has yet been observed. This function is for informational purposes. (e.g. monitoring, logs, etc.)
func (le *LeaderElector) IsLeader() bool
IsLeader returns true if the last observed leader was this client else returns false.
func (le *LeaderElector) Run(ctx context.Context)
Run starts the leader election loop. Run will not return before leader election loop is stopped by ctx or it has stopped holding the leader lease
LeaderMetric instruments metrics used in leader election.
type LeaderMetric interface {
On(name string)
Off(name string)
SlowpathExercised(name string)
}
MetricsProvider generates various metrics used by the leader election.
type MetricsProvider interface {
NewLeaderMetric() LeaderMetric
}
| Name | Synopsis |
|---|---|
| .. | |
| resourcelock | |