This is the expected behavior. The docker containers (the container in your pipeline and the mongo container) are on different networks with different IP addresses, and therefore cannot communicate via localhost. Instead you need to use the container hostname.
Hey bradry appreciate the work on drone.
But could we put some work into cleaning up the docs.
Spent fair to long believing that they were both on local host due to this http://readme.drone.io/usage/services-guide/. Having no idea it was out of date!
I didn’t even know docs.drone.io was a thing! @bradrydzewski