Allow one `trigger` job to start multiple children
Problem to solve
It's awkward to start child pipelines right now because you have to know about ever possible child pipeline and have an independent job that can trigger it. So, for a monorepo for example, any time anyone adds a project you need to add boilerplate code to start the child pipeline.
One approach is to use dynamic child pipelines and allow more than one level of child pipelines (#29651 (closed)), essentially creating one dynamic child pipeline that can then dynamically start as many child pipelines as it needs. This, however, is clumsy.
Intended users
User experience goal
Proposal
Allow one trigger job to indicate that it should start multiple child pipelines, similar to the way parallel can start multiple jobs.
Syntax TBD. If the trigger job logic is too complex, we could potentially introduce a multi-trigger job that can start several trigger jobs in parallel based on the output.