cluster-proxy-addon

README

Cluster Proxy Addon

cluster-proxy-addon uses a reverse proxy server (anp) to send the request from hub to managed cluster. And it also contains e2e test for the overall cluster-proxy-addon case.

This feature has 7 relevant repos:

• cluster-proxy-addon
  • Contains the ANP image (currently version 0.0.24)
  • Contains the HTTP-User-Server image to support users using http way to access the cluster-proxy.
• cluster-proxy
  • The main body of the addon.
  • The repo has some differences in build and deploy part with the upstream repo: cluster-proxy to suit the downstream needs.
• backplane-operator
  • The lastest chart changes should be made in backplane-operator template.
• cluster-proxy-addon-chart
  • Only for release-2.5 and early version.
  • Using images from cluster-proxy-addon and cluster-proxy to deploy the addon.
  • The repo is leveraged by multiclusterhub-operator and multiclusterhub-repo.
• release
  • Contains the cicd steps of the addon.
• apiserver-network-proxy
  • The repo is a forked version to support the downstream needs.
• grpc-go
  • The repo is a forked version to support the proxy-in-middle cases.
  • Used in: https://github.com/stolostron/apiserver-network-proxy/blob/d562699c78201daef7dec97cd1847e5abffbe2ab/go.mod#L5C43-L5C72

The recommanded way for internal operator/controller/service to leverage the cluster-proxy-addon

The cluster-proxy-addon exposed a Route for the users in outside world to access the managed clusters. But for the internal operator/controller/service, it's recommanded to use the Service to access the managed clusters. The Service is also more efficient than the Route in the internal network.

Here is a piece of code to show how to use the cluster-proxy-addon Service to access the managed clusters' pod logs, the full example can be found in multicloud-operators-foundation:

    // There must be a managedserviceaccount with proper rolebinding in the managed cluster.
    logTokenSecret, err := c.KubeClient.CoreV1().Secrets(clusterName).Get(ctx, helpers.LogManagedServiceAccountName, v1.GetOptions{})
	if err != nil {
		return nil, fmt.Errorf("faield to get log token secret in cluster %s. %v", clusterName, err)
	}

    // Configure a kuberentes Config.
	clusterProxyCfg := &rest.Config{
        // The `ProxyServiceHost` normally is the service domain name of the cluster-proxy-addon user-server:
        // cluster-proxy-addon-user.<component namespace>.svc:9092
		Host: fmt.Sprintf("https://%s/%s", c.ProxyServiceHost, clusterName),
		TLSClientConfig: rest.TLSClientConfig{
            // The CAFile must be the openshift-service-ca.crt, because user-server using openshift service CA to sign the certificate.
            // You can mount the openshift-service-ca.crt to the pod, a configmap named `openshift-service-ca.crt` in the every namespace.
			CAFile: c.ProxyServiceCAFile,
		},
		BearerToken: string(logTokenSecret.Data["token"]),
	}
	clusterProxyKubeClient, err := kubernetes.NewForConfig(clusterProxyCfg)
	if err != nil {
		return nil, err
	}

The full example can be found in:

Q&A

The community version of cluster-proxy support grpc mode, does the cluster-proxy-addon support it?

No, the cluster-proxy-addon doesn't support grpc mode. The cluster-proxy-addon only support http mode. This is because for security reasons, cluster-proxy-addon using the flag --enable-kube-api-proxy. By setting the flag to false, the cluster-proxy won't use the managedcluster name as one of the agent-identifiers.

The reason why we don't want to use the managedcluster name as one of the agent-identifiers is that in some customer's environment, the managedcluster name begins with numbers, which is not a valid domain name. But the agent identifier is used as the domain name in the grpc mode.

Currently, all requests from the hub to the managed cluster follow pattern:

 client -> user-server -> proxy-server(ANP) -> proxy-agent(ANP) -> service-proxy -> target-service