title: DNS records are not created for ingress resources
body: <p>My config:</p>
  
  <pre><code>apiVersion: v1
  kind: ServiceAccount
  metadata:
    name: external-dns
    namespace: kube-system
  ---
  apiVersion: rbac.authorization.k8s.io/v1beta1
  kind: ClusterRole
  metadata:
    name: external-dns
  rules:
  - apiGroups: [""]
    resources: ["services"]
    verbs: ["get","watch","list"]
  - apiGroups: [""]
    resources: ["pods"]
    verbs: ["get","watch","list"]
  - apiGroups: ["extensions"] 
    resources: ["ingresses"] 
    verbs: ["get","watch","list"]
  - apiGroups: [""]
    resources: ["nodes"]
    verbs: ["list"]
  - apiGroups: ["networking.istio.io"]
    resources: ["gateways"]
    verbs: ["get","watch","list"]
  ---
  apiVersion: rbac.authorization.k8s.io/v1beta1
  kind: ClusterRoleBinding
  metadata:
    name: external-dns-viewer
  roleRef:
    apiGroup: rbac.authorization.k8s.io
    kind: ClusterRole
    name: external-dns
  subjects:
  - kind: ServiceAccount
    name: external-dns
    namespace: kube-system
  ---
  apiVersion: extensions/v1beta1
  kind: Deployment
  metadata:
    name: external-dns
    namespace: kube-system
  spec:
    strategy:
      type: Recreate
    template:
      metadata:
        labels:
          app: external-dns
      spec:
        serviceAccountName: external-dns
        containers:
        - name: external-dns
          image: registry.opensource.zalan.do/teapot/external-dns:latest
          args:
          - --source=ingress
          - --source=istio-gateway
          - --domain-filter=xxx
          - --policy=upsert-only
          - --provider=azure
          volumeMounts:
          - name: azure-config-file
            mountPath: /etc/kubernetes
            readOnly: true
        volumes:
        - name: azure-config-file
          secret:
            secretName: azuredns-config
  </code></pre>
  
  <p>Istio gateway objects are being parsed and DNS records are being created (this happened a while back, I dont see anything in the log right now). Ingress records are not being parsed, for some reason. I've tried adding <code>--source=service</code> and annotating service with: <code>external-dns.alpha.kubernetes.io/hostname: my.host.name</code>, no effect either. </p>
  
  <p>Any ideas? This looks fine, but somehow doesn't work. Ingress works, cert-manager creates cert, if I manually create DNS record ingress works fine.</p>