external-dns-netcup-webhook

External-DNS Webhook Provider to manage Netcup DNS Records

Note

This repository is not affiliated with Netcup.

Warning

Completely untested code. Might eat your DNS records. You have been warned.

Setting up external-dns for Netcup

This tutorial describes how to setup external-dns for usage within a Kubernetes cluster using Netcup as the domain provider.

Make sure to use external-dns version 0.14.0 or later for this tutorial.

Creating Netcup Credentials

A secret containing the a Netcup API token and an API Password is needed for this provider. You can get a token for your user here.

To create the API token secret you can run kubectl create secret generic netcup-api-key --from-literal=NETCUP_API_KEY=<replace-with-your-access-token>.

To create the API password secret you can run kubectl create secret generic netcup-api-password --from-literal=NETCUP_API_PASSWORD=<replace-with-your-access-token>.

Deploy external-dns

Connect your kubectl client to the cluster you want to test external-dns with.

Besides the API key and password, it is mandatory to provide a customer id as well as a list of DNS zones you want external-dns to manage. The hosted DNS zones will be provides via the --domain-filter.

Then apply one of the following manifests file to deploy external-dns.

$ kubectl create -f example/external-dns.yaml

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", "watch"]
---
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:v0.14.0
        args:
        - --log-level=debug
        - --source=ingress
        - --source=service
        - --provider=webhook
      - name: external-dns-webhook-provider
        image: ghcr.io/mrueg/external-dns-netcup-webhook:latest
        imagePullPolicy: Always
        args:
        - --log-level=debug
        - --domain-filter=YOUR_DOMAIN
        - --netcup-customer-id=YOUR_ID
        env:
        - name: NETCUP_API_KEY
          valueFrom:
            secretKeyRef:
              key: NETCUP_API_KEY
              name: netcup-api-key
        - name: NETCUP_API_PASSWORD
          valueFrom:
            secretKeyRef:
              key: NETCUP_API_PASSWORD
              name: netcup-api-password

Deploying an Nginx Service

Create the deployment and service:

$ kubectl create -f example/nginx.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
spec:
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - image: nginx
        name: nginx
        ports:
        - containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
  name: nginx
  annotations:
    external-dns.alpha.kubernetes.io/hostname: test.example.com
    external-dns.alpha.kubernetes.io/internal-hostname: internaltest.example.com
spec:
  selector:
    app: nginx
  type: LoadBalancer
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80

Note the annotation on the service; use the same hostname as the Netcup DNS zone created above. The annotation may also be a subdomain of the DNS zone (e.g. 'www.example.com').

By setting the TTL annotation on the service, you have to pass a valid TTL, which must be 120 or above. This annotation is optional, if you won't set it, it will be 1 (automatic) which is 300.

external-dns uses this annotation to determine what services should be registered with DNS. Removing the annotation will cause external-dns to remove the corresponding DNS records.

Depending where you run your service it can take a little while for your cloud provider to create an external IP for the service.

Once the service has an external IP assigned, external-dns will notice the new service IP address and synchronize the Netcup DNS records.

Verifying Netcup DNS records

Check your Netcup domain overview to view the domains associated with your Netcup account. There you can view the records for each domain.

The records should show the external IP address of the service as the A record for your domain.

Cleanup

Now that we have verified that external-dns will automatically manage Netcup DNS records, we can delete the tutorial's example:

$ kubectl delete -f example/nginx.yaml
$ kubectl delete -f example/external-dns.yaml

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