LAB 5

This lab assumes your K8S can spin up a LoadBalancer. When you’re using a managed K8S cluster, this should work as explained. Self-managed clusters do not have an integrated external load balancer configured by default. If you feel up to it, you can use the instructions to configure MetalLB with Kind. You need to carefullty check the Docker IPAM range and update the MetalLB configmap.

Setting up MetalLB

Create the metallb namespace

kubectl apply -fhttps://raw.githubusercontent.com/metallb/metallb/main/config/manifests/metallb-native.yaml

Wait for metallb pods to have a status of Running

kubectl get pods -n metallb-system --watch

Check the Docker IPAM range in use

docker network inspect -f '' kind 

Create the MetalLB configmap and match the addresses with the docker IPAM range network.

kubectl apply -f - <<EOF
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: example
  namespace: metallb-system
spec:
  addresses:
  - 172.18.255.200-172.18.255.250
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: empty
  namespace: metallb-system
EOF

You can access the LoadBalancer IP from your lab host.
If you want to make it accissible to the outside world on a KIND cluster, you must add some IPtables rules.

sudo iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 80 -j DNAT --to-destination 172.18.255.200:80
sudo iptables -A FORWARD -p tcp -d 172.18.255.200 --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

Create a service of type LoadBalancer

kubectl apply -f - <<EOF
apiVersion: v1
kind: Service
metadata:
  name: my-nginx-lb
  namespace: prod-nginx
spec:
  type: LoadBalancer
  ports:
  - port: 80
    protocol: TCP
  selector:
    app: nginx
EOF

kubectl get svc -n prod-nginx -o wide
NAME                 TYPE          CLUSTER-IP      EXTERNAL-IP   PORT(S)        AGE    SELECTOR
my-nginx-clusterip   ClusterIP     10.99.180.103   <none>        80/TCP         13m    app=nginx
my-nginx-lb          LoadBalancer  10.107.221.36   <Pending>     80:31062/TCP   105s   app=nginx

Try to reach the NodePort and the LB external ip.

curl http:///127.0.0.1:31062
...
curl http://$NODE:31062
...
curl http:///<external-ip>:80
...