After looking around I couldn't find any place that had step by step instructions to do this. This will show you how to convert any migrated Gitea repo to a mirror repo. Only tested with gitHub repositories.
My use case: I migrated a GitHub repo and all of its issues/releases/etc with the API key option. When you create a fully cloned migration Gitea doesn't let you make it a mirror AFAIK. So you have to go digging through the Gitea database in order to change it to a mirror. And it does in fact work, you can migrate a remote repo in its entirety and thenchange it to mirror. Note: When you change to mirror, it will not mirror anything that requires an API key, it will just mirror the git repo.
Open the Gitea database:
- On default installations
sqlite3 /opt/mailcow-dockerized/data/gitea/gitea/gitea.db
- Or custom installation
sqlite3 gitea.db
in the gitea data directory wherever you installed it