The Objective
To setup a single database container that can be used with multiple applications and frontends.
Preparation
Method 1 - Container Links
This method utilizes the --link flag. Container links are a "legacy feature" of Docker and may become deprecated in a future release. Further reading https://docs.docker.com/network/links/
Method 2 - Docker Networking
Create a Docker network and connect each of the containers to it so they can communicate.
Method 3 - Exposing Host Ports
Expose ports on the host into the container and connect other containers to the host's exposed port