Sonatype does not officially provide instructions to proxy the Iron Bank docker registry (registry1.dso.mil). However, an enterprising user has provided the following steps. use at your own risk.
Warning: This article describes unsupported functionality that is subject to change - test any solutions derived from it.
Before beginning, make sure your web proxy permits access to “registry1.dso.mil”, “registry-1.docker.io”, “ib-prod-harbor-storage.s3.us-gov-west-1.amazonaws.com”, “production.cloudflare.docker.com”, “auth.docker.io”, “index.docker.io”, and “download.docker.com”.
Steps:
1. Request an Iron Bank robot account FAQ - Iron Bank
2. Create a docker proxy repo in Nexus. Remote storage will be “https://registry1.dso.mil”, and “Docker Index” MUST BE “Use Docker Hub”. Also consider enabling anonymous access.
3. Under “Credentials" section, you'll select “Username” for the authentication type. You'll then paste the robot credentials (username/password) you receive from step 1.
Once this is squared away, you should be able to pull images from your Nexus proxy as you would any other.