MetalLB hooks into your Kubernetes cluster, and provides a network load-balancer implementation. In short, it allows you to create Kubernetes services of typeLoadBalancerin clusters that don’t run on a cloud provider, and thus cannot simply hook into paid products to provide load balancers.
Installation
There are multiple ways to install MetalLB, for example
Through manifest
kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.12/config/manifests/metallb-native.yaml
or Helm
helm repo add metallb https://metallb.github.io/metallbhelm install metallb metallb/metallb
The related service, deployment, and pods are in the newly created namespace ‘metallb-system’
‘IPAddressPool’ defines the IP address range that will be allocated to ‘LoadBalancer’ type service. The pool of IPs must be dedicated to MetalLB’s use. You can’t reuse for example the Kubernetes node IPs or IPs controlled by other services.
MetalLB supports two types of traffic policies, Layer2 and BGP.In summary,Layer 2focuses on local network communication, whileBGPhandles routing between different networks and plays a critical role in global Internet connectivity.
apiVersion: metallb.io/v1beta1kind: IPAddressPoolmetadata: name: first-pool namespace: metallb-systemspec: addresses: - 192.168.9.10-192.168.9.20---apiVersion: metallb.io/v1beta1kind: L2Advertisementmetadata: name: example namespace: metallb-systemspec: ipAddressPools: - first-pool
Example
apiVersion: v1kind: Podmetadata: name: nginx labels: app: nginxspec: containers: – name: nginx image: nginx:1.18.0—apiVersion: v1kind: Servicemetadata: name: nginxspec: type: LoadBalancer ports: – port: 80 targetPort: 80 selector: app: nginx
Service ‘nginx’ will be allocated with an external-ip in192.168.9.10-192.168.9.20 defined inIPAddressPool first-pool above, check the assigned external-ip with the command below
kubectl get service/nginx
MetalLB supportsmetallb.universe.tf/loadBalancerIPsannotation to set up service with a specific address.
apiVersion: v1kind: Servicemetadata: name: nginx annotations: metallb.universe.tf/loadBalancerIPs: 192.168.9.35spec: type: LoadBalancer ports: - port: 80 targetPort: 80 selector: app: nginx
MetalLB also supports requesting a specific address pool, when you have multiple pools, for example, one for production public IPs, and one for development private IPs.
apiVersion: v1kind: Servicemetadata: name: nginx annotations: metallb.universe.tf/address-pool: second-poolspec: type: LoadBalancer ports: - port: 80 targetPort: 80 selector: app: nginx