Github action build chain is a tool for github actions to build multiple projects from different repositories in a single action. This tool is trying to solve the problem when a project depends on another project (most probably from the same organization) and one change can/should be performed in different repositories. How can we assure one specific pull request will work with the latest changes from/in the dependant/dependency projects and it won't break something? This is what we call cross-repo pull requests and build-chain is the way we have to solve it.
- archive artifacts mechanism
- pull request flow
- cross-repo checkout