This tutorial describes how to setup ExternalDNS for usage within a Kubernetes cluster using Linode DNS Manager.
Make sure to use >=0.5.5 version of ExternalDNS for this tutorial.
If you want to learn about how to use Linode DNS Manager read the following tutorials:
An Introduction to Managing DNS, and general documentation
Generate a new oauth token by following the instructions at Access-and-Authentication
The environment variable LINODE_TOKEN
will be needed to run ExternalDNS with Linode.
Connect your kubectl
client to the cluster you want to test ExternalDNS with.
Then apply one of the following manifests file to deploy ExternalDNS.
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:v0.13.4
args:
- --source=service # ingress is also possible
- --domain-filter=example.com # (optional) limit to only example.com domains; change to match the zone created above.
- --provider=linode
env:
- name: LINODE_TOKEN
value: "YOUR_LINODE_API_KEY"
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:v0.13.4
args:
- --source=service # ingress is also possible
- --domain-filter=example.com # (optional) limit to only example.com domains; change to match the zone created above.
- --provider=linode
env:
- name: LINODE_TOKEN
value: "YOUR_LINODE_API_KEY"
Create a service file called 'nginx.yaml' with the following contents:
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: my-app.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 Linode DNS zone created above.
ExternalDNS uses this annotation to determine what services should be registered with DNS. Removing the annotation will cause ExternalDNS to remove the corresponding DNS records.
Create the deployment and service:
$ kubectl create -f nginx.yaml
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, ExternalDNS will notice the new service IP address and synchronize the Linode DNS records.
Check your Linode UI to view the records for your Linode DNS zone.
Click on the zone for the one created above if a different domain was used.
This should show the external IP address of the service as the A record for your domain.
Now that we have verified that ExternalDNS will automatically manage Linode DNS records, we can delete the tutorial's example:
$ kubectl delete service -f nginx.yaml
$ kubectl delete service -f externaldns.yaml