Add PollIntervalJitter to Options

[max-melentyev]

Jitter is useful when dealing with large number of resources to avoid load spikes.

I'm going to use this option in further provider-aws PRs.

[negz]

I'm going to use this option in further provider-aws PRs.

Could you open a PR with an example? More context around what you're trying to achieve would help review this PR.

Is the idea to use this with https://github.com/crossplane/crossplane-runtime/blob/v1.15.1/pkg/reconciler/managed/reconciler.go#L566?

I'm wondering whether we really need to be able to plumb down a configurable amount of jitter, or whether an appropriate amount could be derived from the poll interval.

[max-melentyev]

Hi @negz , thanks for reviewing!

I've submitted one of the PRs I mentioned, it has some details: crossplane-contrib/provider-aws#2030. Along with custom poll interval for ec2 instances and route53 records we want to set jitter for them to avoid polling large batches at the same time.

whether an appropriate amount could be derived from the poll interval

With relatively low poll intervals (<= 30m) we just have hardcoded jitters equal pollInterval / 2. Though the plan is later to increase these poll intervals even further up to several hours. And in this case it will make sense to have jitters less than pollInterval / 2. I'm also not sure if jitter is needed for other resources that have short poll intervals.

[max-melentyev]

Another thing to consider: I think provider-aws will still require custom controller.Options struct that extends crossplane-runtime Options to let controllers subscribe to EventBridge events to trigger reconciliations for their managed resources. So I can add jitter to that struct if it doesn't make sense for other providers.

[negz]

Another thing to consider: I think provider-aws will still require custom controller.Options struct that extends crossplane-runtime Options to let controllers subscribe to EventBridge events to trigger reconciliations for their managed resources.

My preference would be to start there. If we then find it ends up being used a lot we could add it to this widely used struct.