These are Docker stack definitions in docker-compose format. Each represents a separate service running in Swarm.

• If this repo contains a custom image definition published to Docker hub, its stack definition is sym-linked to the docker-compose.yml file in the same directory as its Dockerfile

• Environment variables, labels and external secrets are local settings which are kept in a separate private git repo. They're each referenced explicitly in the environment section of each compose file, rather than by reference to a separate env_file, for clarity.

With the rise in popularity of Kubernetes in 2018, usage of docker-compose file format is declining. I'm no longer using these files and there is no validation testing to confirm they still work.