func New()

in pkg/lease/lease.go [129:198]
61 lines of code
10 McCabe index (conditional complexity)

func New(
	logger log.Logger,
	metrics prometheus.Registerer,
	lock resourcelock.Interface,
	opts *Options,
) (*Lease, error) {
	if logger == nil {
		logger = log.NewNopLogger()
	}
	if opts == nil {
		opts = &Options{}
	}
	if opts.LeaseDuration == 0 {
		opts.LeaseDuration = 15 * time.Second
	}
	if opts.RetryPeriod == 0 {
		opts.RetryPeriod = 2 * time.Second
	}
	if opts.RenewDeadline == 0 {
		opts.RenewDeadline = 10 * time.Second
	}
	if metrics != nil {
		if err := metrics.Register(leaseHolder); err != nil {
			return nil, err
		}
		if err := metrics.Register(leaseFailingOpen); err != nil {
			return nil, err
		}
	}
	leaseHolder.WithLabelValues(lock.Describe()).Set(0)
	leaseFailingOpen.WithLabelValues(lock.Describe()).Set(0)

	wlock := newWrappedLock(lock)

	lease := &Lease{
		logger:         logger,
		lock:           wlock,
		onLeaderChange: func() {},
		opts:           *opts,
	}

	var err error
	// We use the Kubernetes client-go leader implementation to drive the lease logic.
	// The lock itself however may be implemented against any consistent backend.
	lease.elector, err = leaderelection.NewLeaderElector(leaderelection.LeaderElectionConfig{
		Lock:          wlock,
		LeaseDuration: opts.LeaseDuration,
		RetryPeriod:   opts.RetryPeriod,
		RenewDeadline: opts.RenewDeadline,
		// The purpose of our lease is to determine time ranges for which a leader sends
		// sample data. We cannot be certain that we never sent data for a later in-range
		// timestamp already. Thus releasing the lease on cancel would produce possible
		// overlaps.
		ReleaseOnCancel: false,
		Callbacks: leaderelection.LeaderCallbacks{
			OnStartedLeading: func(context.Context) {
				lease.onLeaderChange()
				leaseHolder.WithLabelValues(lock.Describe()).Set(1)
			},
			OnStoppedLeading: func() {
				lease.onLeaderChange()
				leaseHolder.WithLabelValues(lock.Describe()).Set(0)
			},
		},
	})
	if err != nil {
		return nil, err
	}
	return lease, nil
}