Cluster Networking

Set up reliable networking for your Raspberry Pi K3s cluster, including static IPs, hostnames, and local DNS options.

Before installing K3s, it’s important to ensure that all nodes can communicate consistently over the network.

In this lesson, you’ll configure static IP addresses, hostnames, and optionally set up a local DNS or hosts file for easier management.

🌐 Why Networking Matters in Kubernetes

K3s (and Kubernetes) rely heavily on:

• IP-based communication between control-plane and worker nodes
• Internal container networking (via CNI plugins)
• External access for load balancing and services

Without stable networking, your cluster will be unreliable or fail to form properly.

✅ Step 1: Assign Static IPs

🛠 Option A: DHCP Reservation (Recommended)

• Login to your home router or DHCP server
• Reserve a static IP for each Pi based on its MAC address

🧠 This is the easiest and most router-friendly method.

🛠 Option B: Static IP on the Device

If your router doesn’t support reservations, configure static IPs directly:

Edit netplan config (Ubuntu):

sudo nano /etc/netplan/00-installer-config.yaml

Example:

network:
  ethernets:
    eth0:
      dhcp4: no
      addresses: [192.168.1.100/24]
      gateway4: 192.168.1.1
      nameservers:
        addresses: [1.1.1.1, 8.8.8.8]
  version: 2

Apply changes:

sudo netplan apply

🧩 Step 2: Set Consistent Hostnames

Each Pi should have a unique, meaningful hostname:

sudo hostnamectl set-hostname pi-master

Also update /etc/hosts:

127.0.0.1   localhost
127.0.1.1   pi-master

Repeat on all nodes (e.g., pi-node1, pi-node2).

🧰 Step 3: Test Network Connectivity

On each Pi, ping the others:

ping pi-node1.local
ping 192.168.1.101

If .local doesn’t work, use IPs or set up a shared /etc/hosts file on all nodes:

192.168.1.100 pi-master
192.168.1.101 pi-node1
192.168.1.102 pi-node2

🔧 Optional: Set Up Local DNS with Pi-hole or dnsmasq

If you’re managing a home lab or multiple clusters, consider setting up Pi-hole or dnsmasq to provide:

• DNS-based hostnames (e.g. pi-master.localdomain)
• Automatic IP resolution
• Blocklists and ad filtering (bonus!)

🧪 Test Summary

You’re ready to move forward when:

• ✅ All nodes have static IPs
• ✅ Each node has a unique hostname
• ✅ You can SSH and ping all nodes from each other

Next up: Installing K3s

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