For those curious about the relation to the existing CI used in opam-repository, then it is no coincidence that @talex5 is the author of both 
This DSL is the next iteration of the datakit-ci, but specialised to be faster and simpler for extending with OCaml and more complex workflows that our OCaml Platform tools need these days (like ocamlformat linting, or dune expect promotion, or odoc cross-referenced doc generation). We are planning a smooth migration next year over to the new system, but wanted to release this early to show you some of the pieces going into this new iteration. I am particularly excited about the new tty-based interface that saves an awful lot of clicking around on web UIs for CI results…