Issuing a Virtual IP to a Service Using MetalLB on Kubernetes

MetalLB is a load balancer implementation for bare metal Kubernetes clusters, using L2 advertisements. This tutorial will guide you through the process of setting up MetalLB in your Kubernetes cluster and assigning a virtual IP to a service.

Step 1: Install MetalLB

MetalLB can be installed via a manifest or using Helm. We'll use the manifest method here.

1. Apply the MetalLB manifest:

kubectl apply -f
https://raw.githubusercontent.com/metallb/metallb/v0.13.12/con
fig/manifests/metallb-native.yaml

Note: Ensure you're using the latest version of MetalLB.

2. Verify the Installation.

kubectl get pods -n metallb-system

You should see the MetalLB pods running.

Step 2: Configure MetalLB

MetalLB can operate in either Layer 2 mode or BGP mode. We'll use Layer 2 mode for simplicity.

1. Create a ConfigMap for MetalLB: Define a range of IP addresses that MetalLB will manage. Create a file named metallb-pool.yaml with the following content:

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
name: ippool
  namespace: metallb-system
spec:
  addresses:
  - 192.168.1.200/32
  - 192.168.1.240-192.168.1.250

Replace 192.168.1.240-192.168.1.250 with your desired IP range.

Apply the Pool:

kubectl apply -f metallb-pool.yaml

2. Create a L2 Advertisement: When additional IP ranges are defined in the config- map, they need to be advertised on to the network. Create a file named L2add.yaml with the following content:

apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: example
  namespace: metallb-system
spec:
  ipAddressPools:
  - ippool

Apply the advertisement:

kubectl apply -f L2add.yaml

Step 3: Create a Service with a Virtual IP

Let’s expose the wordpress application: Edit the service of type LoadBalancer on wordpress-service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: wordpress
spec:
  selector:
    app: wordpress
  ports:
    - protocol: TCP
port: 80
      targetPort: 80
  type: LoadBalancer

Save and apply it:

kubectl apply -f wordpress-service.yaml

Check the Service:

kubectl get svc wordpress-service

3. MetalLB will assign an external IP from the defined range to your service.

Step 4: Access the Service

• You can now access the wordpress server using the external IP provided by MetalLB. This IP is accessible within your network.

Troubleshoot

On a different VM than the master do the testing for ARP advertisements.

Remove MetalLB (Only for the reference)

arp -a
ping 192.168.1.200
sudo apt install iputils-arping
arping 192.168.1.200

Remove MetalLB (Only for the reference)

kubectl delete -f
https://raw.githubusercontent.com/metallb/metallb/v0.13.12/con
fig/manifests/metallb-native.yaml
kubectl delete -f metallb-pool.yaml
kubectl delete -f L2add.yaml
kubectl get all -n metallb-system

Kubernetes Ingress. (Optional)

In a Kubernetes environment, if you want to use an Ingress resource to direct traffic to a service that's exposed via NodePort, while still allowing users to access the service using a standard port (like port 80) without specifying the NodePort, you can set it up as follows:

Step 1: Expose Your Service Using NodePort

1. Create a Service of Type NodePort for Your Web Application: Suppose you have a deployment named webapp. You'll need to create a service for it. Here's an example YAML for the service:

apiVersion: v1
kind: Service
metadata:
  name: webapp-nodeport-service
spec:
  type: NodePort
  selector:
    app: webapp
  ports:
    - port: 80
      targetPort: 80
      protocol: TCP