[kichik]

CodeBuild can be a bit slow to start sometimes. It also doesn't support Docker on Windows builds and it's limited to 8 hours per run.

Shameless plug: I wrote a CDK construct that lets you create runners on demand in response to a GitHub webhook (so basically what was suggested here only with handling of more corner cases that came up). It lets you start runners in CodeBuild, Fargate, ECS, EC2, or Lambda so you can pick whichever works best for you. There is a table in the readme that shows the difference between them and why you might want to choose one over the other. https://github.com/CloudSnorkel/cdk-github-runners