Load Balancer

5. Load Balancer (MetalLB)

MetalLB allows the use of LoadBalancer type services in a bare-metal environment like our K3s cluster.

5.1 Install MetalLB

# Create namespace
sudo kubectl create namespace metallb-system --kubeconfig /etc/rancher/k3s/k3s.yaml

# Install MetalLB using Helm
sudo helm repo add metallb https://metallb.github.io/metallb --kubeconfig /etc/rancher/k3s/k3s.yaml
sudo helm repo update --kubeconfig /etc/rancher/k3s/k3s.yaml
sudo helm install metallb metallb/metallb --namespace metallb-system --kubeconfig /etc/rancher/k3s/k3s.yaml

5.2 Configure the IP address pool

Create an ipaddresspool.yaml file with the following content (adjust the IP range according to your network):

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: first-pool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.1.200-192.168.1.220

Apply the configuration:

sudo kubectl apply -f ipaddresspool.yaml --kubeconfig /etc/rancher/k3s/k3s.yaml

5.3 Configure the advertisement mode

Create an l2advertisement.yaml file with the following content:

apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: l2-advert
  namespace: metallb-system
spec:
  ipAddressPools:
  - first-pool

Apply the configuration:

sudo kubectl apply -f l2advertisement.yaml --kubeconfig /etc/rancher/k3s/k3s.yaml

5.4 Test MetalLB

Create a test application:

# Create an NGINX deployment
sudo kubectl create deployment nginx --image=nginx --kubeconfig /etc/rancher/k3s/k3s.yaml

# Expose the deployment as a LoadBalancer type service
sudo kubectl expose deployment nginx --port=80 --type=LoadBalancer --kubeconfig /etc/rancher/k3s/k3s.yaml

# Verify that an external IP has been assigned
sudo kubectl get svc nginx --kubeconfig /etc/rancher/k3s/k3s.yaml

You should see an external IP address assigned from the pool you configured (192.168.1.200-192.168.1.220). You can access NGINX using this IP from any machine on your network.

You can also see which IP it is running on from OpenLens: