What causes "lost event send interval must be greater than 0" in cilium/cilium?

Pass a positive duration, e.g. WithLostEventSendInterval(1 * time.Second).

lost event send interval must be greater than 0

Error message

lost event send interval must be greater than 0

What it means

WithLostEventSendInterval is an observer option that sets how often lost-event notifications are sent; the interval must be strictly positive. A zero or negative duration is rejected by the option function so the observer is never configured with a nonsensical interval.

Source

Thrown at pkg/hubble/observer/observeroption/option.go:148

	return func(o *Options) error {
		o.MonitorBuffer = size
		return nil
	}
}

// WithMaxFlows that the ring buffer is initialized to hold.
func WithMaxFlows(capacity container.Capacity) Option {
	return func(o *Options) error {
		o.MaxFlows = capacity
		return nil
	}
}

// WithLostEventSendInterval sets the interval at which lost events are sent.
func WithLostEventSendInterval(interval time.Duration) Option {
	return func(o *Options) error {
		if interval <= 0 {
			return errors.New("lost event send interval must be greater than 0")
		}
		o.LostEventSendInterval = interval
		return nil
	}
}

// WithOnServerInit adds a new callback to be invoked after server initialization
func WithOnServerInit(f OnServerInit) Option {
	return func(o *Options) error {
		o.OnServerInit = append(o.OnServerInit, f)
		return nil
	}
}

// WithOnServerInitFunc adds a new callback to be invoked after server initialization
func WithOnServerInitFunc(f func(Server) error) Option {
	return WithOnServerInit(OnServerInitFunc(f))
}

View on GitHub (pinned to ac7b90affa)

Solutions

Pass a positive duration, e.g. WithLostEventSendInterval(1 * time.Second).
If the value comes from config, validate/default it before applying options.
Omit the option entirely to use the default LostEventSendInterval.

Example fix

// before
WithLostEventSendInterval(cfg.LostEventInterval) // 0 when unset
// after
if cfg.LostEventInterval > 0 { opts = append(opts, WithLostEventSendInterval(cfg.LostEventInterval)) }

Defensive patterns

Strategy: validation

Validate before calling

if interval <= 0 {
    return fmt.Errorf("lost event send interval must be positive, got %v", interval)
}
opts = append(opts, WithLostEventSendInterval(interval))

Try / catch

if err := opt(o); err != nil {
    var d time.Duration
    _ = d
    return fmt.Errorf("observer option failed: %w", err)
}

Prevention

Default unset durations to a sane positive value before building options.
Wrap option application and log which option failed.
Never pass raw config durations without bounds-checking.

When it happens

Trigger: Calling observeroption.WithLostEventSendInterval(0) or with a negative time.Duration (e.g. -time.Second) when building observer options.

Common situations: Programmatic construction of Hubble observers/standalone servers where a config value defaults to 0 because the config key was unset and no default fallback was applied.

Understand the failure class

Background: "must be positive", "Invalid value": how libraries reject invalid parameter values (ValueError, ArgumentError, INVALID_PARAMETER_VALUE) — this error's family across 28 libraries.

Related errors

AI-assisted analysis of cilium/cilium@ac7b90affa (2026-08-31). Data as JSON: /api/errors/efef2a0263f6d65d. Report an issue: GitHub.