In Kubernetes, an Ingress is a way to describe how to route traffic coming into the cluster, so that (for example) https://radarr.example.com will end up on a Radarr pod, but https://sonarr.example.com will end up on a Sonarr pod.
This is a companion discussion topic for the original entry at https://geek-cookbook.funkypenguin.co.nz/kubernetes/ingress/