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Setting up ExternalDNS for Oracle Cloud Infrastructure (OCI)

This tutorial describes how to setup ExternalDNS for usage within a Kubernetes cluster using OCI DNS.

Make sure to use the latest version of ExternalDNS for this tutorial.

Creating an OCI DNS Zone

Create a DNS zone which will contain the managed DNS records. Let's use example.com as an reference here.

For more information about OCI DNS see the documentation here.

Deploy ExternalDNS

Connect your kubectl client to the cluster you want to test ExternalDNS with. We first need to create a config file containing the information needed to connect with the OCI API.

Create a new file (oci.yaml) and modify the contents to match the example below. Be sure to adjust the values to match your own credentials:

auth:
  region: us-phoenix-1
  tenancy: ocid1.tenancy.oc1...
  user: ocid1.user.oc1...
  key: |
    -----BEGIN RSA PRIVATE KEY-----
    -----END RSA PRIVATE KEY-----
  fingerprint: af:81:71:8e...
  # Omit if there is not a password for the key
  passphrase: Tx1jRk...
compartment: ocid1.compartment.oc1...

Create a secret using the config file above:

$ kubectl create secret generic external-dns-config --from-file=oci.yaml

Manifest (for clusters with RBAC enabled)

Apply the following manifest to deploy ExternalDNS.

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"]
---
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
        - --provider=oci
        - --policy=upsert-only # prevent ExternalDNS from deleting any records, omit to enable full synchronization
        - --txt-owner-id=my-identifier
        volumeMounts:
          - name: config
            mountPath: /etc/kubernetes/
      volumes:
      - name: config
        secret:
          secretName: external-dns-config

Verify ExternalDNS works (Service example)

Create the following sample application to test that ExternalDNS works.

For services ExternalDNS will look for the annotation external-dns.alpha.kubernetes.io/hostname on the service and use the corresponding value.

apiVersion: v1
kind: Service
metadata:
  name: nginx
  annotations:
    external-dns.alpha.kubernetes.io/hostname: example.com
spec:
  type: LoadBalancer
  ports:
  - port: 80
    name: http
    targetPort: 80
  selector:
    app: nginx
---
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
          name: http

Apply the manifest above and wait roughly two minutes and check that a corresponding DNS record for your service was created.

$ kubectl apply -f nginx.yaml