'''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
}}}