Setting up External DNS with Contour

This tutorial describes how to configure External DNS to use either the Contour IngressRoute or HTTPProxy source. The IngressRoute CRD is deprecated but still in-use in many clusters however it's recommended that you migrate to the HTTPProxy resource. Using the HTTPProxy resource with External DNS requires Contour version 1.5 or greater.

Example manifests for External DNS

Without RBAC

Note that you don't need to enable both of the sources and if you don't enable contour-ingressroute you also don't need to configure the contour-load-balancer setting.

apiVersion: apps/v1
kind: Deployment
metadata:
  name: external-dns
spec:
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: external-dns
  template:
    metadata:
      labels:
        app: external-dns
    spec:
      containers:
      - name: external-dns
        image: registry.k8s.io/external-dns/external-dns:v0.13.1
        args:
        - --source=service
        - --source=ingress
        - --source=contour-ingressroute # To enable IngressRoute support
        - --source=contour-httpproxy # To enable HTTPProxy support
        - --contour-load-balancer=custom-contour-namespace/custom-contour-lb # For IngressRoute ONLY: load balancer service to be used. Omit to use the default (heptio-contour/contour) 
        - --domain-filter=external-dns-test.my-org.com # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
        - --provider=aws
        - --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
        - --aws-zone-type=public # only look at public hosted zones (valid values are public, private or no value for both)
        - --registry=txt
        - --txt-owner-id=my-identifier

With RBAC

apiVersion: v1
kind: ServiceAccount
metadata:
  name: external-dns
---
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: external-dns
rules:
- apiGroups: [""]
  resources: ["services","endpoints","pods"]
  verbs: ["get","watch","list"]
- apiGroups: ["extensions","networking.k8s.io"]
  resources: ["ingresses"] 
  verbs: ["get","watch","list"]
- apiGroups: [""]
  resources: ["nodes"]
  verbs: ["list"]
# This section is only for IngressRoute
- apiGroups: ["contour.heptio.com"]
  resources: ["ingressroutes"]
  verbs: ["get","watch","list"]
# This section is only for HTTPProxy
- apiGroups: ["projectcontour.io"]
  resources: ["httpproxies"]
  verbs: ["get","watch","list"]
---
apiVersion: rbac.authorization.k8s.io/v1
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: default
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: external-dns
spec:
  strategy:
    type: Recreate
  selector:
    matchLabels:
      app: external-dns
  template:
    metadata:
      labels:
        app: external-dns
    spec:
      serviceAccountName: external-dns
      containers:
      - name: external-dns
        image: registry.k8s.io/external-dns/external-dns:v0.13.1
        args:
        - --source=service
        - --source=ingress
        - --source=contour-ingressroute # To enable IngressRoute support
        - --source=contour-httpproxy # To enable HTTPProxy support
        - --contour-load-balancer=custom-contour-namespace/custom-contour-lb # For IngressRoute ONLY: load balancer service to be used. Omit to use the default (heptio-contour/contour) 
        - --domain-filter=external-dns-test.my-org.com # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
        - --provider=aws
        - --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
        - --aws-zone-type=public # only look at public hosted zones (valid values are public, private or no value for both)
        - --registry=txt
        - --txt-owner-id=my-identifier

Verify External DNS works

The following instructions are based on the Contour example workload.

Install a sample service

$ kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: kuard
  name: kuard
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kuard
  template:
    metadata:
      labels:
        app: kuard
    spec:
      containers:
      - image: gcr.io/kuar-demo/kuard-amd64:1
        name: kuard
---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: kuard
  name: kuard
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: kuard
  sessionAffinity: None
  type: ClusterIP
EOF

Then create either a HTTPProxy or an IngressRoute

HTTPProxy

$ kubectl apply -f - <<EOF
apiVersion: projectcontour.io/v1
kind: HTTPProxy
metadata:
  labels:
    app: kuard
  name: kuard
  namespace: default
spec:
  virtualhost:
    fqdn: kuard.example.com
  routes:
    - conditions:
      - prefix: /
      services:
        - name: kuard
          port: 80
EOF

IngressRoute

$ kubectl apply -f - <<EOF
apiVersion: contour.heptio.com/v1beta1
kind: IngressRoute
metadata: 
  labels:
    app: kuard
  name: kuard
  namespace: default
spec: 
  virtualhost:
    fqdn: kuard.example.com
  routes: 
  - match: /
    services: 
    - name: kuard
      port: 80
EOF

Access the sample service using `curl`

$ curl -i http://kuard.example.com/healthy
HTTP/1.1 200 OK
Content-Type: text/plain
Date: Thu, 27 Jun 2019 19:42:26 GMT
Content-Length: 2

ok

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