V3 of Sonarr running in a mono:5.20 (debian9) container with gradheim python systemd replacement.
For version 3 of Sonarr run:
docker run -d --name sonarr3 -p 8989:8989 exist2resist/sonarr:latest
or
docker run -d --name sonarr3 -p 8989:8989 exist2resist/sonarr:v3