There seems to be a problem with DRONE_HOST:
If drone is behind a reverse proxy, drone builds its webhooks from the HOST heaser in Http requests.
What is DRONE_HOST for?
As mentioned in this issue https://github.com/drone/drone/issues/2336
it is quite confusing. Of course drone behind a proxy can’t know its own address -> This is what I would expect this variable for
In the documentation you might mention:
proxy_set_header Host $host;
as this seems to be what drone is looking for (at least it is not highlighted)
DRONE_HOST was a last-minute hotfix, because we could not ascertain the hostname for GRPC requests. So if you have a reverse proxy sitting in front of Drone, you need to set both the DRONE_HOST and the X-Forwarded-* variables. We have some sample configurations available, for reference http://docs.drone.io/setup-with-nginx/
Eventually DRONE_HOST will be the only required configuration, but that will require some refactoring. I would expect it to be addressed in 0.9.