Kubernetes
Self-hosted Kubernetes
Following this handbook in Chinese.
Install kubeadm
Required ports
When running Kubernetes in an environment with strict network boundaries, such as on-premises datacenter with physical network firewalls or Virtual Networks in Public Cloud, it is useful to be aware of the ports and protocols used by Kubernetes components.
Control plane (Master)
| Protocol | Direction | Port Range | Purpose | Used By |
|---|---|---|---|---|
| TCP | Inbound | 6443 | Kubernetes API server | All |
| TCP | Inbound | 2379-2380 | etcd server client API | kube-apiserver, etcd |
| TCP | Inbound | 10250 | Kubelet API | Self, Control plane |
| TCP | Inbound | 10259 | kube-scheduler | Self |
| TCP | Inbound | 10257 | kube-controller-manager | Self |
Although etcd ports are included in control plane section, you can also host your own. etcd cluster externally or on custom ports.
On Ubuntu, you should configure the ufw(Ubuntu firewall) to allow the ports.
for p in "6443/tcp" "2379:2380/tcp" "10250/tcp" "10259/tcp" "10257/tcp"; do sudo ufw allow "$p"; done
Worker node(s)
| Protocol | Direction | Port Range | Purpose | Used By |
|---|---|---|---|---|
| TCP | Inbound | 10250 | Kubelet API | Self, Control plane |
| TCP | Inbound | 10256 | kube-proxy | Self, Load balancers |
| TCP | Inbound | 30000-32767 | NodePort Services | All |
† Default port range for NodePort Services.
All default port numbers can be overridden. When custom ports are used those ports need to be open instead of defaults mentioned here.
On Ubuntu, you should configure the ufw(Ubuntu firewall) to allow the ports.
for p in "10250/tcp" "10256/tcp" "30000:32767/tcp"; do sudo ufw allow "$p"; done
One common example is API server port that is sometimes switched to 443. Alternatively, the default port is kept as is and API server is put behind a load balancer that listens on 443 and routes the requests to API server on the default port.