Rate limiting

It is possible to rate limit reconciliation on a per-resource basis. The rate limit takes precedence over retry/reschedule configurations: for example, even if a retry would reschedule a reconciliation but this request would make the resource go over its rate limit, the next reconciliation will be postponed according to the rate limiting rules. Note that the reconciliation is never cancelled, it will just be executed as early as possible based on rate limitations.

Rate limiting is by default turned off, since correct configuration depends on the reconciler implementation, in particular, on how long a typical reconciliation takes.

Rate limiting is configured per controller, see ControllerConfiguration.

The default LinearRateLimiter

We provide a generic rate limiter implementation: LinearRateLimiter.

To configure it, use the @RateLimited annotation on your Reconciler class. The following configuration limits each resource to reconcile at most twice within a 3 second interval:

@RateLimited(maxReconciliations = 2, within = 3, unit = TimeUnit.SECONDS)
@ControllerConfiguration
public class MyReconciler implements Reconciler<MyCR> {

}

Thus, if a given resource was reconciled twice in one second, no further reconciliation for this resource will happen before two seconds have elapsed. Note that, since rate limiting is on a per-resource basis, other resources can still be reconciled at the same time, as long as they stay within their own rate limits.

Custom Rate Limiter

You can provide your own rate limiter by implementing the RateLimiter interface and setting it either through:

• explicit configuration, or
• the rateLimiter field of the @ControllerConfiguration annotation.

For the annotation approach, similarly to Retry implementations, RateLimiter implementations must provide an accessible, no-arg constructor for instantiation purposes and can further be automatically configured from your own annotation, provided that your RateLimiter implementation also implements the AnnotationConfigurable interface, parameterized by your custom annotation type.