I'm trying to use rewrite target from kubernetes with gcloud but it doesn't seem to be respected. My code is the following. Maybe there's something I'm not seen:

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: demo-ingress
  annotations:
    ingress.kubernetes.io/rewrite-target: /
    kubernetes.io/ingress.global-static-ip-name: projectip
spec:

  rules:
  - host: mycustomdomain.com
    http:
      paths:
      - path: /*
        backend:
          serviceName: frontend
          servicePort: 80
      - path: /api/*
        backend:
          serviceName: backend
          servicePort: 80

When I do curl mycustomdomain.com/api/something my backend is always receiving backend/api/something instead of backend/something. I'm really out of ideas and I could use some help.