Metal Lb : A Kubernetes Load balancer for non cloud environments

In this post I will show how to install a load balancer for non-cloud environment and depends on premises.

Metal LB provides a load balancer for non cloud environment and allow to create the “LoadBalancer” service type in Kubernetes clusters that don’t run on a cloud provider.

Project site : https://metallb.universe.tf/concepts/

1. Network Modes

There are two types for network mode :

• layer 2: In layer 2 mode, one machine in the cluster takes ownership of the service, and uses standard address discovery protocols (ARP for IPv4, NDP for IPv6) to make those IPs reachable on the local network.
• layer 3 by BGP: In BGP mode, all machines in the cluster establish BGP peering sessions with nearby routers that you control, and tell those routers how to forward traffic to the service IPs. Using BGP allows for true load balancing across multiple nodes

In this article, the overlay network for the pods is done with Calico. You can also use Flannel,Weavenet or Romana.

So, I would like to create a simple lab with layer 2 with this post and I recommend to read the documentation before any deployment.

2. Laboratory

I wrote a post with all details for Kubernetes deployment with Ansible.

My lab :

[root@master1 ~]# kubectl get nodes 
NAME      STATUS   ROLES    AGE   VERSION
master1   Ready    master   9d    v1.17.4
master2   Ready    master   9d    v1.17.4
master3   Ready    master   9d    v1.17.4
worker1   Ready    <none>   9d    v1.17.4
worker2   Ready    <none>   9d    v1.17.4
worker3   Ready    <none>   9d    v1.17.4

3. Metal LB configuration

Always check the last version from official repository.

Install the metal lb :

# Create the metal lb namespace
$ kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.9.3/manifests/namespace.yaml
# Create a secret on first install only
$ kubectl create secret generic -n metallb-system memberlist --from-literal=secretkey="$(openssl rand -base64 128)"

# Install metal lb 
$ https://raw.githubusercontent.com/google/metallb/v0.9.3/manifests/metallb.yaml

• The metallb-system/controller deployment. This is the cluster-wide controller that handles IP address assignments.
• The metallb-system/speaker daemonset. This is the component that speaks the protocol(s) of your choice to make the services reachable.
• Service accounts for the controller and speaker, along with the RBAC permissions that the components need to function.

Create a metallb-configmap.yaml file to configure the IP for network . So , in my scenario my layer 2 range is 192.168.15.0/24 .

$ vi  metallb-config.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  namespace: metallb-system
  name: config
data:
  config: |
    address-pools:
    - name: my-ip-space
      protocol: layer2
      addresses:
      - 192.168.15.11-192.168.15.15

I reserve 5 ips from range in the config map above, then apply this config map configuration :

$ kubectl apply -f metallb-config.yml

Create a Nginx pod for validate the configution :

vi nginx-pod.yaml 

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:latest
        ports:
        - containerPort: 80

Apply the pod yaml :

$  kubectl apply -f  nginx-pod.yml

Create a service with Loadbalancer service type :

vi nginx-service.yaml 

apiVersion: v1
kind: Service
metadata:
  name: nginx
spec:
  type: LoadBalancer
  selector:
    app: nginx
  ports:
  - port: 80
    name: http

Apply the service yaml :

$  kubectl apply -f  nginx-service.yml

Check the services on cluster :

$ kubectl get svc 
NAME                        TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)        AGE
kubernetes                  ClusterIP      10.233.0.1      <none>          443/TCP        46h
nginx                       LoadBalancer   10.233.50.165   192.168.15.11   80:30651/TCP   5m41s

We can access my web pod Nginx with ip 192.168.15.11 as showed above :

$ curl  192.168.15.11

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>