Hi Ingo,
Your linkerd, frontend service, and ingress configs look good, thanks for providing those!
Are you also running actual instances of your 'frontend' service? For example, a Deployment or ReplicationController? If there are no pods running instances of your 'frontend' service, there's nothing for linkerd to route to.
You can confirm linkerd is correctly routing in minkube by testing `/svc/l5d` in the admin dtab interface.
If you have more questions, try create an issue on
https://discourse.linkerd.io/, it's easier for us to track, and you'll probably get a better response.
Cheers,
Andrew