[idonttalkenough]

>And I had a heck of a time getting a config that allows each contained thing to see the others

Use a utility container to learn some of the network/options of docker. The network-multitool[1] container is a good one I use.

So for example, create a few containers in a manifests/compose file with different network settings and try pinging, telneting, etc from one container to another.

This container can also be used to help debug workload containers that are having connectivity issues. If you need more tooling just create an image with this container as a base.

[1]https://github.com/wbitt/Network-MultiTool