Change default docker registry?

I use internal network not public internet network.
I make docker private registry, docker-nexus.bak.com

And use drone:1.6.0 and agent:1.6.0 using docker.

How to pull drone/git from docker-nexus.bak.com not https://registry-1.docker.io/v2/?
drone installed in internal network can not access https://registry-1.docker.io/v2/

Instead of pulling from the registry you can build the drone/git:1 image on the machine. Drone will use the image in the local Docker cache:

$ git clone https://github.com/drone/drone-git.git
$ cd drone-git
$ docker build -f docker/Dockerfile.linux.amd64 -t drone/git:1 .

or you can pull the image from nexus onto the machine, and then re-tag the image. Drone will use the tagged image in the local cache:

$ docker pull docker-nexus.bak.com/drone-git
$ docker tag docker-nexus.bak.com/drone-git drone/git:1