If you are using a private registry with a self-signed certificate, and need to connect to it from a macOS laptop, you are likely to incur in the following error:

$ docker-compose up -d
 Pulling search (docker.registry.mydomain.io:5000/image:2.0.1)...
 ERROR: Get https://docker.registry.mydomain.io:5000/v1/_ping: x509:
 certificate signed by unknown authority

it turns that (a) there is not much of information that is applicable out there and that (b) it is dead easy to fix.

Simply click on the menu bar icon and choose Preferences (or hit Cmd-,) and in the Advanced pane, add the full hostname:port for your private registry.

Then Apply & Restart and you’re good to go.