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Speeding up caching on Cirrus Runners

Adding Cirrus Runners to your GitHub project has a great benefit of increasing the build speed, yet reducing the costs and making spendings much more predictable. However, Cirrus Runners act as self-hosted runners which means that the runners now are outside the GitHub infrastructure hosted predominantly on Azure, and this comes at a cost of cache accesses potentially being slower than they could be.

Do you use actions/cache in your workflows? Then this might be especially of interest to you.

Optimizing startup time of Cirrus Runners

We recently added OpentTelemetry Traces alongside Metrics in order to gain a deeper understanding of areas for potential optimizations.

Previously with only high level metrics we had a limited visibility into how GitHub Actions jobs are running on Cirrus Runners platform. We only measured several executing related metrics: delivery lag of GitHub webhooks, scheduling time of a job within Cirrus Runners Scheduler and how long it takes to actually start a single use virtual machine to execute a job. Here is a schema that represents our previously limited visibility:

Execution Schema