Open Sourcing our Drone CI/CD CloudWatch Auto Scaler

AssemblyAI uses Drone as their primary CI/CD tool, but needed a cost-effective and easily scalable solution for their GPU instances. They decided to use Docker Runners and built drone-queue-cloudwatch, an open-source tool that sends Drone build stats to Cloudwatch and lets it handle scaling. The tool uses Node Routing to define which worker group handles a given build and publishes metrics for running builds in order to control scaling. It also considers the build queue depth as the effective metric for scaling. The code is available on GitHub, and there are example Terraform files for implementation.