This repository demonstrates a minimalist implementation of path filtering on CircleCI.
Everything is implemented inside a single config .circleci/config.yml. The setup workflow/job runs on .circleci/config.yml, then it spools .circleci/config.yml again for continuation. For continuing workflows, the setup job passes 3 parameters (i.e., run-setup, run-module-a and run-module-b) to tell which job should run and which should not: For instance, run-setup is always set to false to avoid running the setup job again, and run-module-a / run-module-b will be set to true if (and only if) changes are made in module-a / module-b directory, respectively.