⚠️ This software is experimental and NOT FIT FOR PRODUCTION USE!

🛈 NOTE: This Webhook was forked and modified from the IONOS Webhook to work with Hetzner. It also contains huge parts from DrBu7cher's Hetzner provider.

ExternalDNS is a Kubernetes add-on for automatically managing Domain Name System (DNS) records for Kubernetes services by using different DNS providers. By default, Kubernetes manages DNS records internally, but ExternalDNS takes this functionality a step further by delegating the management of DNS records to an external DNS provider such as Hetzner. Therefore, the Hetzner webhook allows to manage your Hetzner domains inside your kubernetes cluster with ExternalDNS.

To use ExternalDNS with Hetzner, you need your Hetzner API token of the account managing your domains. For detailed technical instructions on how the Hetzner webhook is deployed using the Bitnami Helm charts for ExternalDNS, seedeployment instructions.

The Hetzner webhook is provided as a regular Open Container Initiative (OCI) image released in the GitHub container registry. The deployment can be performed in every way Kubernetes supports. The following example shows the deployment as a sidecar container in the ExternalDNS pod using the Bitnami Helm charts for ExternalDNS.

⚠️ This webhook requires at least ExternalDNS v0.14.0.

helm repo add bitnami https://charts.bitnami.com/bitnami
kubectl create secret generic hetzner-credentials --from-literal=api-key='<EXAMPLE_PLEASE_REPLACE>'

You can then create the helm values file, for example external-dns-hetzner-values.yaml:

image:
  registry: registry.k8s.io
  repository: external-dns/external-dns
  tag: v0.14.0

provider: webhook

extraArgs:
  webhook-provider-url: http://localhost:8888
  txt-prefix: reg-

sidecars:
  - name: hetzner-webhook
    image: ghcr.io/mconfalonieri/external-dns-hetzner-webhook:v0.5.1
    ports:
      - containerPort: 8888
        name: webhook
      - containerPort: 8080
        name: http
    livenessProbe:
      httpGet:
        path: /health
        port: http
      initialDelaySeconds: 10
      timeoutSeconds: 5
    readinessProbe:
      httpGet:
        path: /ready
        port: http
      initialDelaySeconds: 10
      timeoutSeconds: 5
    env:
      - name: HETZNER_API_KEY
        valueFrom:
          secretKeyRef:
            name: hetzner-credentials
            key: api-key

And then:

# install external-dns with helm
helm install external-dns-hetzner bitnami/external-dns -f external-dns-hetzner-values.yaml

The following environment variables are available:

Additional environment variables for domain filtering:

If the REGEXP_DOMAIN_FILTER is set, the following variables will be used to build the filter:

• REGEXP_DOMAIN_FILTER
• REGEXP_DOMAIN_FILTER_EXCLUSION

otherwise, the filter will be built using:

• DOMAIN_FILTER
• EXCLUDE_DOMAIN_FILTER

While tweaking the configuration, there are some points to take into consideration:

• if WEBHOOK_HOST and HEALTH_HOST are set to the same address/hostname or one of them is set to 0.0.0.0 remember to use different ports.

• if your records don't get deleted when applications are uninstalled, you might want to verify the policy in use for ExternalDNS: if it's upsert-only no deletion will occur. It must be set to sync for deletions to be processed. Please add the following to external-dns-hetzner-values.yaml if you want this strategy:

  policy: sync

The basic development tasks are provided by make. Run make help to see the available targets.