In modern Kubernetes environments, managing network resources efficiently is crucial for ensuring the seamless operation of applications. Load balancing is a fundamental aspect of distributing incoming network traffic across multiple instances of an application, enhancing performance and ensuring high availability. MetalLB, a widely-used service for Kubernetes, provides a solution for load balancing within the cluster. One of its operational modes, Layer 2 mode, dynamically assigns Layer 2 IP addresses to services, making it suitable for network environments that require Layer 2 functionality.

In this blog post, we will delve into the process of deploying MetalLB in Layer 2 mode. We will walk through the essential steps to set up MetalLB within your Kubernetes cluster and configure it to work efficiently in Layer 2 mode. By the end of this guide, you will have a solid understanding of how to harness MetalLB's capabilities to optimize load balancing in your Kubernetes environment. So, let's begin the journey of exploring MetalLB and its Layer 2 deployment mode to enhance the networking aspects of your Kubernetes applications.

Deploy

1. If you’re using kube-proxy in IPVS mode, since Kubernetes v1.14.2 you have to enable strict ARP mode.

    kubectl get configmap kube-proxy -n kube-system -o yaml | \
    sed -e "s/strictARP: false/strictARP: true/" | \
    kubectl apply -f - -n kube-system
   

   Note, you don’t need this if you’re using kube-router as service-proxy because it is enabling strict ARP by default.

2. Apply the MetalLB manifest from the metallb-native.yaml file

     kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.10/config/manifests/metallb-native.yaml
   

   This will deploy MetalLB to your cluster, under the metallb-system namespace. The components in the manifest are:

   • 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.

3. Create metallb ip pool and L2Advertisement, change address with range ip in your network subnet.

    vim metallb-config.yaml
   
    apiVersion: metallb.io/v1beta1
    kind: IPAddressPool
    metadata:
      name: default
      namespace: metallb-system
    spec:
      addresses:
      - 20.20.20.30-20.20.20.50
   
    ---
    apiVersion: metallb.io/v1beta1
    kind: L2Advertisement
    metadata:
      name: l2adv
      namespace: metallb-system
    spec:
      ipAddressPools:
      - default
   

4. Apply manifest

   kubectl apply -f metallb-config.yaml
   

5. Test create deployment with lb service

    vim nginx-lb.yaml
   
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: nginx-loadbalancer-deployment
    spec:
      replicas: 3
      selector:
        matchLabels:
          app: nginx
      template:
        metadata:
          labels:
            app: nginx
        spec:
          containers:
          - name: nginx
            image: nginx:latest
            ports:
            - containerPort: 80
   
    ---
   
    apiVersion: v1
    kind: Service
    metadata:
      name: nginx-loadbalancer-service
    spec:
      selector:
        app: nginx
      type: LoadBalancer
      ports:
      - name: http
        port: 80
        targetPort: 80
        protocol: TCP
   

6. Apply manifest

    kubectl apply -f nginx-lb.yaml
   

7. Monitor the resources, now the lb service should be getting an IP.

   

8. Try to reach assigned ip with arping and curl the service