Locally Visit Services Running in Child Clusters

How to visit services running in child clusters as locally

For services/pods running in child clusters, we can use port-forward to visit them locally.

First please make sure kubectl clusternet must be at or later than version v0.7.0. Please follow how to upgrade clusternet plugin with krew.

$ kubectl clusternet version
  "gitVersion": "0.7.0",
  "gitCommit": "42ce8b65d04d838563a411a61706a21349431b8b",
  "buildDate": "2022-08-22T03:27:19Z",
  "platform": "darwin/arm64"

1. Get the cluster ID

We list all the ManagedClusters to get the cluster id we want.

$ kubectl get mcls -A
NAMESPACE          NAME                       CLUSTER ID                             SYNC MODE   KUBERNETES   STATUS   AGE
clusternet-jjz75   clusternet-cluster-9gc5d   c1a5e75c-9e38-4279-b1c9-2345e612b9e5   Dual        v1.23.8      True     11m

2. View the services running in child cluster

Now we list services in default namespace of managed cluster with ID c1a5e75c-9e38-4279-b1c9-2345e612b9e5.

$ kubectl clusternet get svc --cluster-id=c1a5e75c-9e38-4279-b1c9-2345e612b9e5 --child-kubeconfig=./child-kubeconfig
kubernetes      ClusterIP    <none>        443/TCP   27m
my-nginx-test   ClusterIP    <none>        80/TCP    4m46s

3. Forward a local port to a port on the service

kubectl clusternet port-forward allows using resource name, such as a service name, to select a matching service to port forward to. It follows the same usage as kubectl port-forward, but appending two extra arguments --cluster-id and --child-kubeconfig.

$ kubectl clusternet port-forward --namespace default \
  --cluster-id=c1a5e75c-9e38-4279-b1c9-2345e612b9e5 \
  --child-kubeconfig=./child-kubeconfig \
  svc/my-nginx-test 8080:80
Forwarding from -> 80
Forwarding from [::1]:8080 -> 80
Handling connection for 8080

Now in another terminal, we can locally visit the services running in child cluster (cluster ID: c1a5e75c-9e38-4279-b1c9-2345e612b9e5) now. The output is similar to:

$ curl http://localhost:8080
<!DOCTYPE html>
<title>Welcome to nginx!</title>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
<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>