This repository provides a utility named bb_autoscaler that can be used in
combination with Buildbarn Remote Execution
to automatically adjust the size of Amazon EC2
Auto Scaling Groups (ASGs),
EKS Managed Node Groups,
or Kubernetes deployments
of Buildbarn workers based on load. Load metrics are obtained by
querying Prometheus, which in its turn extracts metrics from
bb_scheduler. It relies on Prometheus to normalize the load metrics
into a desired number of workers (e.g., by using
quantile_over_time()).
Furthermore, this repository provides a tool named
bb_asg_lifecycle_hook, which may be used to gracefully downscale
workers running on plain EC2 instances, using
EC2 ASG lifecycle hooks.
Note that it may not always be necessary to use utilities like these. When using Kubernetes, it may be sufficient to create a Horizontal Pod Autoscaler that uses the Custom Metrics API. Using these tools may still be preferable if it is undesirable to reconfigure your cluster to use the Custom Metrics API.