In this article we will look how we can configure extra port mappings and IPv6 networking
Extra Port Mappings
Can be used to port forward to the kind nodes, an option to get traffic into the cluster
Useful if we are using NodePort services or DaemonSets exposing host ports
To use port mappings with NodePort, the kind node containerPort and the service nodePort needs to be equal
In the below configuration file containerPort is set as 30080, so we need to set nodePort in Kubernetes service as 30080
$ cat kind.yml
apiVersion: kind.x-k8s.io/v1alpha4
kind: Cluster
name: dev
nodes:
- role: control-plane
extraPortMappings:
- containerPort: 30080
hostPort: 30080
listenAddress: "0.0.0.0"
protocol: TCP
- role: worker
- role: worker
Create the cluster using the above configuration file
$ kind create cluster --config kind.yml
Creating cluster "dev" ...
✓ Ensuring node image (kindest/node:v1.26.3) 🖼
✓ Preparing nodes 📦 📦 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
✓ Joining worker nodes 🚜
Set kubectl context to "kind-dev"
You can now use your cluster with:
kubectl cluster-info --context kind-dev
$ kubectl get nodes
NAME STATUS ROLES AGE VERSION
dev-control-plane Ready control-plane 93s v1.26.3
dev-worker Ready <none> 62s v1.26.3
dev-worker2 Ready <none> 62s v1.26.3
Generate a manifest file for creating an Nginx pod
$ kubectl run nginx --image=nginx --port=80 --dry-run=client -o yaml > nginx.yml
$ cat nginx.yml
apiVersion: v1
kind: Pod
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx
spec:
containers:
- image: nginx
name: nginx
ports:
- containerPort: 80
resources: {}
dnsPolicy: ClusterFirst
restartPolicy: Always
status: {}
Apply the nginx.yml manifest file
$ kubectl apply -f nginx.yml
pod/nginx created
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
nginx 1/1 Running 0 19s
Generate a manifest file for exposing the Nginx service as NodePort
$ kubectl expose pod nginx --name=nginx-nodeport --type=NodePort --port=80 --target-port=80 --dry-run=client -o yaml > nginx-nodeport.yml
Update the manifest file with nodePort value as 30080, which is equal to the kind node containerPort
$ cat nginx-nodeport.yml
apiVersion: v1
kind: Service
metadata:
creationTimestamp: null
labels:
run: nginx
name: nginx-nodeport
spec:
ports:
- port: 80
protocol: TCP
targetPort: 80
nodePort: 30080
selector:
run: nginx
type: NodePort
status:
loadBalancer: {}
Apply the nginx-nodeport.yml manifest file
$ kubectl apply -f nginx-nodeport.yml
service/nginx-nodeport created
$ kubectl get svc nginx-nodeport
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx-nodeport NodePort 10.96.152.109 <none> 80:30080/TCP 43s
Verify the Nginx default webpage from your local machine
$ curl http://localhost:30080
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
IPv6 Networking
kind has support for IPv4, IPv6 and dual-stack networking
By default it uses IPv4
Most OS has IPv6 enabled by default but we can check it using the below command
sudo sysctl net.ipv6.conf.all.disable_ipv6
Create a cluster using the below configuration file which uses IPv6 networking
$ cat kind.yml
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: dev
networking:
ipFamily: ipv6
nodes:
- role: control-plane
- role: worker
- role: worker
$ kind create cluster --config kind.yml
Creating cluster "dev" ...
✓ Ensuring node image (kindest/node:v1.26.3) 🖼
✓ Preparing nodes 📦 📦 📦
✓ Writing configuration 📜
✓ Starting control-plane 🕹️
✓ Installing CNI 🔌
✓ Installing StorageClass 💾
✓ Joining worker nodes 🚜
Set kubectl context to "kind-dev"
You can now use your cluster with:
kubectl cluster-info --context kind-dev
Once the cluster is up and running, we can see that the nodes have an IPv6 address
$ kubectl get nodes -o wide
NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME
dev-control-plane Ready control-plane 10m v1.26.3 fc00:f853:ccd:e793::4 <none> Ubuntu 22.04.2 LTS 5.15.0-69-generic containerd://1.6.19-46-g941215f49
dev-worker Ready <none> 10m v1.26.3 fc00:f853:ccd:e793::2 <none> Ubuntu 22.04.2 LTS 5.15.0-69-generic containerd://1.6.19-46-g941215f49
dev-worker2 Ready <none> 9m58s v1.26.3 fc00:f853:ccd:e793::3 <none> Ubuntu 22.04.2 LTS 5.15.0-69-generic containerd://1.6.19-46-g941215f49
Now let’s check it by creating an Nginx pod and exposing it as ClusterIP
$ kubectl run nginx --image=nginx --port=80 --expose
service/nginx created
pod/nginx created
$ kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx 1/1 Running 0 18s fd00:10:244:1::2 dev-worker <none> <none>
$ kubectl get svc nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx ClusterIP fd00:10:96::ca5a <none> 80/TCP 3m23s
Cleanup
Delete the cluster after use
$ kind delete cluster --name dev
Deleting cluster "dev" ...
Deleted nodes: ["dev-worker2" "dev-control-plane" "dev-worker"]
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