We use the Elastic CI stack for AWS, but also have some fixed agents in the same queue. The goal would be that the elastis stack only scales when all the fixed agents are busy.
Is it possible that the AutoscalingFunction works on modified measurements for the Buildkite Queue (e.g. if we have 10 fixed agents, we want ScheduledJobsCount to be max(0, x-10)? I have no insight into this part, so I’d be grateful if someone could give me a quick hint before I start digging.
This small adjustment should be sufficient to avoid unnecessary scaling with additional fixed agents in the queue.
Thanks for confirming about using the clusters, @bunert!
We discussed the issue with the team and the short answer would be “it is not possible in the exact way you’re thinking it would work”, however it can be accomplished in a different way.
A work-around for this would be separating your jobs into tasks of different priority and using different queues. For instance, with a “priority” queue for your fixed agents and an “elastic” queue for the EC2 agents. But it is not possible to only trigger the AWS agents once all of your fixed ones are busy without some clever scripting.
The idea here would be to use two queues in the cluster, one primary/fixed queue and one EC2 queue, and use scripting to flip the queue based on a conditional (you’d want to experiment here). But a direct approach like you’re thinking isn’t possible/not supported at this time.
Hello, @bunert! Glad to see that you found a workaround that is working for you. If you need help with anything else - we’re always here, happy to help.
