Path filtering + config splitting on CircleCI

This repository demonstrates an advanced use case of dynamic config feature on CircleCI. For instance, it implements both path filtering and config splitting.

Files

• .circleci/config.yml implements both 1) the dynamic config, and 2) common resources (i.e., jobs and commands) for main workflows/jobs. These common resources are shared among every module.
• module-a/.circleci/config.yml, module-b/.circleci/config.yml, and module-c/.circleci/config.yml implement independent modular configs for module A, B, and C, respectively.

How does it work?

1. Upon the initial trigger, CircleCI triggers the setup job setup-dynamic-config defined in .circleci/config.yml.
2. Given a list of directories, detect which subdirectories (in this case, modules modules) have changes. (cf. list-changed-modules)
3. Fetch path-to-module/.circleci/config.yml for each module to build, and merge all the fetched config.yml (along with the config defining common resources, i.e., .circleci/config.yml) using yq. (cf. merge-modular-configs)
4. Trigger execution of the merged config.