Load balancer

Metallb

For the load balancer we are using the metallb. Theoretically we could have used the integratetd one from the k3s, but the integrated one is not able to handle virtual IPs. Alternative we could have used the kube-vip but the provided controller from kube-vip is not mature enough. If we ever decide to use kube-vip then we will have to update the kube-vip daemon set and activate the --service parameter.

Metallb provides a helm chart. So the installation is quite simple:

helm repo add metallb https://metallb.github.io/metallb
kubectl create namespace load-balancer
helm install --namespace load-balancer load-balancer metallb/metallb -f values.yaml --version 0.14.3
# Wait for the full deployment of the services
kubectl apply -f IPAddressPool.yaml
kubectl apply -f vpa.yaml

The values.yaml I used is:

# https://github.com/metallb/metallb/blob/main/charts/metallb/values.yaml

prometheus:
  serviceAccount: "prometheus-k8s"
  namespace: "monitoring"
  podMonitor:
    enabled: true

controller:
  image:
    pullPolicy: IfNotPresent

speaker:
  image:
    pullPolicy: IfNotPresent

Note

Initially the prometheus monitoring should not be activate until we deploy the monitoring stack. Afterwards we can activate it.

Validation

To make sure that the assignment of the IPs is working, we will create a small testing service

kubectl create namespace kube-verify
kubectl apply -f verify.yaml

With verify.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: kube-verify
  namespace: kube-verify
  labels:
    app: kube-verify
spec:
  replicas: 3
  selector:
    matchLabels:
      app: kube-verify
  template:
    metadata:
      labels:
        app: kube-verify
    spec:
      containers:
      - name: nginx
        image: quay.io/clcollins/kube-verify:01
        ports:
        - containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: kube-verify
  namespace: kube-verify
spec:
  selector:
    app: kube-verify
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080
  type: LoadBalancer
  loadBalancerIP: 192.168.179.249

The test service should be now availalbe in the IP we specified in verify. Once we make certain that everything is working we can deleting the validation service:

kubectl delete -f verify.yaml
kubectl delete namespace kube-verify

Userfull commands:

To get all the assigned IPs we just execute:

kubectl get services -o wide --all-namespaces | grep --color=never -E 'LoadBalancer|NAMESPACE'

Resources:

• https://opensource.com/article/20/7/homelab-metallb
• https://www.devtech101.com/2019/02/23/using-metallb-and-traefik-load-balancing-for-your-bare-metal-kubernetes-cluster-part-1/
• https://metallb.universe.tf/configuration/
• https://github.com/metallb/metallb/issues/308
• https://opensource.com/article/20/7/homelab-metallb