Get pods/events in all child clusters through clusternet-hub

[byliu]

What type of PR is this?

Now we can get pods/events in all child clusters through clusternet-hub.

What this PR does / why we need it:

Get pods/events directly through clusternet-hub.

clusternet-hub

# kubectl clusternet -n test052601-prj-hx2t8pc2 get pod -o wide
NAME                 READY   STATUS    RESTARTS   AGE   IP           NODE         NOMINATED NODE   READINESS GATES
basic-template-0     1/1     Running   0          63d   9.xxx.0.xx   9.xxx.0.xx   <none>           2/2
basic-template11-0   1/1     Running   0          63d   9.xxx.0.xx    9.xxx.0.xx   <none>           2/2
basic-template3-0    1/1     Running   0          91d   9.xxx.0.xx    9.xxx.0.xx   <none>           1/1

the details of child clusters:
child-cluster-1

# kubectl -n test052601-prj-hx2t8pc2 get pod -o wide
NAME                 READY   STATUS    RESTARTS   AGE   IP           NODE         NOMINATED NODE   READINESS GATES
basic-template-0     1/1     Running   0          63d   9.xxx.0.xx   9.xxx.0.   <none>           2/2
basic-template3-0    1/1     Running   0          91d   9.xxx.0.xx    9.xxx.0.xx   <none>           1/1

child-cluster-2

# kubectl -n test052601-prj-hx2t8pc2 get pod -o wide
NAME                 READY   STATUS    RESTARTS   AGE   IP           NODE         NOMINATED NODE   READINESS GATES
basic-template11-0   1/1     Running   0          63d   9.xxx.0.xx    9.xxx.0.xx   <none>           2/2

What we need to do?

add flag --cluster-server-url-out-cls for clusternet-agent if it's running in-cluster
egg

      - command:
        - /usr/local/bin/clusternet-agent
        - --cluster-reg-token=$(REG_TOKEN)
        - --cluster-reg-parent-url=$(PARENT_URL)
        - --cluster-sync-mode=Dual
        - --feature-gates=SocketConnection=true,AppPusher=true,Recovery=true
        - --leader-elect-resource-namespace=$(AGENT_NAMESPACE)
        - --cluster-server-url-out-cls=https://{ClusterServerURLOutCluster}

replace {ClusterServerURLOutCluster} with your child cluster's apiserverURL

[dixudx]

Thanks for your contribution.

Some extra changes are needed.

[dixudx]

We do have this in childKubeConfig.Host.

[dixudx]

No need. There are already a secret in the dedicated namespace, which can be used as the kubeconfig for child clusters.

And it is NOT safe to put kubeconfig in ManagedCluster.

[dixudx]

Need more considerations for security, extensibility, and maintainability.

[dixudx]

Currently only pods and events are allowed, but what if users want to list CRs in child clusters in the future?

[dixudx]

This seems to be wrong. I do NOT see any objects concentration here.

Here it just returns results from the last cluster.

[dixudx]

A big shout out to how the RABC rules should be set for this up-to-bottom GET operations to child clusters.
It seems admin account from child cluster is used here for listing operations.