How to structure DevOps related code and configs in a code repository?
I can answer bout docker, one of the best practice to use docker is to keep the docker file and the compose files in the same repository of the project, so wherever you clone the project you can build the docker image, and it is good to keep multiple versions of docker compose files for example (prod, staging, dev) so you can build the image and run the container with specific option for each env for example for dev machine you can use specific network and run more dependencies container or whatever.