io.pedestal.http.body-params/body-params can do this, but not out of the box (it supports JSON, EDN, transit, and HTTP forms out of the box) ; you can plug in a parser for yaml pretty easily I suspect.

Ok I'll try to take that route, I guess the parse is pluggable via service map?

If you need a YAML parser, I'm one of the maintainers of https://github.com/clj-commons/clj-yaml, which is a wrapper around SnakeYAML. Drop by #C042XAQFCCU if you decide to use it and have any questions.