This repository demonstrates the core concept of CircleCI's setup workflow feature.
The most fundamental understanding for the setup workflow feature is that users can execute two configs in a single pipeline, i.e., one for the setup workflow/job, and the other for main workflows/jobs. While setup workflows/jobs need to be implemented in .circleci/config.yml, you can use any arbitrary valid config for the main workflows/jobs.
In this demonstration, we generate /tmp/another-config.yml in the setup job, and then spool it for the main job. The execution of another-config.yml is triggered by calling POST /pipeline/continue with continuation-key and configuration parameters conveyed as the request body encoded in JSON.