Docker & Postgres: Failed to bind tcp 0.0.0.0:5432 address already in use

Problem

I'm trying to start postgres in a docker container on my Mac, but I keep getting the following error message

docker: Error response from daemon: driver failed programming external connectivity on endpoint postgres (8392b9e5cfaa28f480fe1009dee461f97e82499726f4afc4e916358dd2d2f61e): Error starting userland proxy: Failed to bind tcp 0.0.0.0:5432 address already in use.

I have…