MetalLB hooks into your Kubernetes cluster, and provides a network load-balancer implementation.
It allows you to create Kubernetes services of type "LoadBalancer" in clusters that don't run on a cloud provider, and thus cannot simply hook into 3rd party products to provide load-balancers.
The default operationg mode of MetalLB is in ["Layer2"](https://metallb.universe.tf/concepts/layer2/) but it can also operate in ["BGP"](https://metallb.universe.tf/concepts/bgp/) mode.
You have to explicitly enable the MetalLB extension and set an IP address range from which to allocate LoadBalancer IPs.
```yaml
metallb_enabled: true
metallb_speaker_enabled: true
metallb_ip_range:
- 10.5.0.0/16
```
By default only the MetalLB BGP speaker is allowed to run on control plane nodes. If you have a single node cluster or a cluster where control plane are also worker nodes you may need to enable tolerations for the MetalLB controller:
```yaml
metallb_controller_tolerations:
- key: "node-role.kubernetes.io/master"
operator: "Equal"
value: ""
effect: "NoSchedule"
- key: "node-role.kubernetes.io/control-plane"
operator: "Equal"
value: ""
effect: "NoSchedule"
```
## BGP Mode
When operating in BGP Mode MetalLB needs to have defined upstream peers:
```yaml
metallb_protocol: bgp
metallb_ip_range:
- 10.5.0.0/16
metallb_peers:
- peer_address: 192.0.2.1
peer_asn: 64512
my_asn: 4200000000
- peer_address: 192.0.2.2
peer_asn: 64513
my_asn: 4200000000
```
When using calico >= 3.18 you can replace MetalLB speaker by calico Service LoadBalancer IP advertisement.
See [calico service IPs advertisement documentation](https://docs.projectcalico.org/archive/v3.18/networking/advertise-service-ips#advertise-service-load-balancer-ip-addresses).
In this scenarion you should disable the MetalLB speaker and configure the `calico_advertise_service_loadbalancer_ips` to match your `metallb_ip_range`