The kubectl cluster-info returns URL where the Kubernetes control plane is running at. None of my droplets / load balancers have the public IP address returned by nslookup of that URL. My questions are: What is exactly running at the URL (some special service managed by DO that forwards the requests to the cluster) ? Is it possible to apply firewall rules so kubectl can be executed only from a specific IP address (VPN) ? I saw worker-node-firewalls but I think the public firewall only accepts / drops packets to the nodes.

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Question

Kubernetes control plane URL access

Posted on March 9, 2022

DigitalOcean Cloud Firewalls

DigitalOcean Managed Kubernetes

By rafalkawecki

The kubectl cluster-info returns URL where the Kubernetes control plane is running at. None of my droplets / load balancers have the public IP address returned by nslookup of that URL.

My questions are:

What is exactly running at the URL (some special service managed by DO that forwards the requests to the cluster) ?
Is it possible to apply firewall rules so kubectl can be executed only from a specific IP address (VPN) ? I saw worker-node-firewalls but I think the public firewall only accepts / drops packets to the nodes.

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Bobby

March 10, 2022

Hello,

The control plane configuration is fully managed by DigitalOcean. You cannot modify the control plane files, feature gates, or admission controllers.

For more information on the managed elements of DigitalOcean Kubernetes check out the documentation here:

https://docs.digitalocean.com/products/kubernetes/resources/managed/

Hope that this helps!

Best,

Bobby

July 8, 2024

Hi there,

A quick update here in case that anyone comes across this in the future.

DigitalOcean has just announced that Control plane firewalls are now available in Early Availability.

The feature improves security and traffic for your cluster. Once enabled, only configured IP addresses, cluster worker nodes and workloads, and internal systems that manage the cluster (such as cluster upgrades) can access the control plane.

Existing open connections continue to work until they terminate. However, for WATCH requests, the API server enforces a maximum of 30 minutes for terminating the open connection.

For more information, see How to Add a Control Plane Firewall.

- Bobby