Validate IPv4/IPv6 dual-stack [page]deterministic
This document shares how to validate IPv4/IPv6 dual-stack enabled Kubernetes clusters.
##
* Provider support for dual-stack networking (Cloud provider or otherwise must be able to provide Kubernetes nodes with routable IPv4/IPv6 network interfaces) * A [network plugin](/docs/concepts/extend-kubernetes/compute-storage-net/network-plugins/) that supports dual-stack networking. * [Dual-stack enabled](/docs/concepts/services-networking/dual-stack/) cluster
> Note: While you can validate with an earlier version, the feature is only GA and officially supported since v1.23.
## Validate addressing
### Validate node addressing
Each dual-stack Node should have a single IPv4 block and a single IPv6 block allocated. Validate that IPv4/IPv6 Pod address ranges are configured by running the following command. Replace the sample node name with a valid dual-stack Node from your cluster. In this example, the Node's name is `k8s-linuxpool1-34450317-0`:
```shell kubectl get nodes k8s-linuxpool1-34450317-0 -o go-template --template='{{range .spec.podCIDRs}}{{printf "%s\n" .}}{{end}}' ```
``` 10.244.1.0/24 2001:db8::/64 ```
There should be one IPv4 block and one IPv6 block allocated.
Validate that the node has an IPv4 and IPv6 interface detected. Replace node name with a valid node from the cluster. In this example the node name is `k8s-linuxpool1-34450317-0`:
```shell kubectl get nodes k8s-linuxpool1-34450317-0 -o go-template --template='{{range .status.addresses}}{{printf "%s: %s\n" .type .address}}{{end}}' ```
``` Hostname: k8s-linuxpool1-34450317-0 InternalIP: 10.0.0.5 InternalIP: 2001:db8:10::5 ```
### Validate Pod addressing
Validate that a Pod has an IPv4 and IPv6 address assigned. Replace the Pod name with a valid Pod in your cluster. In this example the Pod name is `pod01`:
```shell kubectl get pods pod01 -o go-template --template='{{range .status.podIPs}}{{printf "%s\n" .ip}}{{end}}' ```
``` 10.244.1.4 2001:db8::4 ```
You can also validate Pod IPs using the Downward API via the `status.podIPs` fieldPath. The following snippet demonstrates how you can expose the Pod IPs via an environment variable called `MY_POD_IPS` within a container.
```yaml env: - name: MY_POD_IPS valueFrom: fieldRef: fieldPath: status.podIPs ```
The following command prints the value of the `MY_POD_IPS` environment variable from within a container. The value is a comma separated list that corresponds to the Pod's IPv4 and IPv6 addresses.
```shell kubectl exec -it pod01 -- set | grep MY_POD_IPS ```
``` MY_POD_IPS=10.244.1.4,2001:db8::4 ```
The Pod's IP addresses will also be written to `/etc/hosts` within a container. The following command executes a cat on `/etc/hosts` on a dual stack Pod. From the output you can verify both the IPv4 and IPv6 IP address for the Pod.
```shell kubectl exec -it pod01 -- cat /etc/hosts ```
``` # Kubernetes-managed hosts file. 127.0.0.1 localhost ::1 localhost ip6-localhost ip6-loopback fe00::0 ip6-localnet fe00::0 ip6-mcastprefix fe00::1 ip6-allnodes fe00::2 ip6-allrouters 10.244.1.4 pod01 2001:db8::4 pod01 ```
## Validate Services
Create the following Service that does not explicitly define `.spec.ipFamilyPolicy`. Kubernetes will assign a cluster IP for the Service from the first configured `service-cluster-ip-range` and set the `.spec.ipFamilyPolicy` to `SingleStack`.
Use `kubectl` to view the YAML for the Service.
```shell kubectl get svc my-service -o yaml ```
The Service has `.spec.ipFamilyPolicy` set to `SingleStack` and `.spec.clusterIP` set to an IPv4 address from the first configured range set via `--service-cluster-ip-range` flag on kube-controller-manager.
```yaml apiVersion: v1 kind: Service metadata: name: my-service namespace: default spec: clusterIP: 10.0.217.164 clusterIPs: - 10.0.217.164 ipFamilies: - IPv4 ipFamilyPolicy: SingleStack ports: - port: 80 protocol: TCP targetP …(trimmed)