MetalLB load balancer#

MetalLB is a load balancer designed for bare metal Kubernetes clusters that uses standard routing protocols.

Prerequisites#

An MKE 4k cluster that does not already have load-balancing functionality.
A MetalLB-compatible cluster network configuration.
kube-proxy running in iptables mode.
The absence of any cloud provider configuration.

Configuration#

MetalLB is configured through the spec.metallb.enabled section of the mke4.yaml configuration file. The function is disabled by default, and thus to use MetalLB you must set the enabled parameter to true.

MetalLB example configuration:

spec:
  metallb:
    enabled: true

Info

that is deployed by a Helm chart within the cluster. Free Range Routing (FRR) mode is disabled by default.

To configure MetalLB:

Obtain the default mke4.yaml configuration file:
```
mkectl init
```
In the mke4.yaml configuration file, add the metallb section under spec and set the enabled parameter to true, as metallb is disabled by default.
```
spec:
  metallb:
    enabled: true
```
Apply the configuration:
```
mkectl apply -f mke4.yaml
```

Verify the successful deployment of MetalLB in the cluster:

kubectl get pods,services,deployments -n metallb-system -l app.kubernetes.io/name=metallb

Example output:

NAME                                      READY   STATUS    RESTARTS   AGE
pod/metallb-controller-79d6b8bb85-c2hrm   1/1     Running   0          17m
pod/metallb-speaker-ccpdf                 1/1     Running   0          17m
pod/metallb-speaker-x2pgf                 1/1     Running   0          17m
NAME                              TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/metallb-webhook-service   ClusterIP   10.96.8.155   none          443/TCP   17m
NAME                                 READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/metallb-controller   1/1     1            1           17m

Configuration parameters#

An MKE version comparison for MetalLB configuration parameters is offered in the following table:

MKE 3	MKE 4k
`[cluster_config.metallb_config.enabled]`	`addons.metallb.enabled`
`[[cluster_config.metallb_config.metallb_ip_addr_pool]]`	`Deprecated`

IP address pool configuration#

Support for IP address pool configuration is deprecated in MKE 4k, and as such the configuration must now be managed independently.

Create IP address pools in a fresh installation#

For information on how to create IP address pools, refer to the official MetalLB documentation, Layer 2 configuration.

The following example configuration gives MetalLB control over IPs from 192.168.1.240 to 192.168.1.250, and configures Layer 2 mode.

---
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: cheap
  namespace: metallb-system
spec:
  addresses:
  - 192.168.10.0/24
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: empty
  namespace: metallb-system

As necessary, refer to the official MetalLB documentation, Advanced AddressPool.

Managing IP address pools during upgrade#

During an upgrade from MKE 3 to MKE 4k, if metalLB is enabled in the former the configured IP address pool details display in the upgrade summary.

The following example configuration presents MetalLB enabled in MKE 3:

[cluster_config.metallb_config]
  enabled = true
  [[cluster_config.metallb_config.metallb_ip_addr_pool]]
    name = "example1"
    external_ip = ["192.168.10.0/24", "192.168.1.0/24"]
  [[cluster_config.metallb_config.metallb_ip_addr_pool]]
    name = "example2"
    external_ip = ["192.155.10.0/24"]

The upgrade summary presents as follows:

MetalLB IP address pools
---------------
name: example1
ipaddress: [192.168.10.0/24 192.168.1.0/24]
name: example2
ipaddress: [192.155.10.0/24]
Please make sure that you create these pools after MKE4 installation is complete.

Refer to the upgrade summary for guidance in the creation of IP address pools. To create the pools, you can use the template that follows or consult the official MetalLB documentation Layer 2 configuration for assistance.

apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: example1
  namespace: metallb-system
spec:
  addresses:
  - 192.168.10.0/24
  - 192.168.1.0/24
---
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: example2
  namespace: metallb-system
spec:
  addresses:
  - 192.155.10.0/24
---
apiVersion: metallb.io/v1beta1
kind: L2Advertisement
metadata:
  name: empty
  namespace: metallb-system

Request specific IP address pools#

With MetalLB, you can request assignment from a specific address pool, if you prefer a particular IP address type but do not require an exact address. To do this, add metallb.universe.tf/address-pool to your service, setting the annotation value to the name of your chosen address pool.

MetalLB example configuration:

apiVersion: v1
kind: Service
metadata:
  name: nginx
  annotations:
    metallb.universe.tf/address-pool: production-public-ips
spec:
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: nginx
  type: LoadBalancer

For more information, refer to the official MetalLB documentation Requesting specific IPs.

Uninstall MetalLB#

Obtain the mke4.yaml configuration file.
Set the enabled field to false to disable MetalLB.
```
mkectl mke4.yaml
```
Apply the configuration:
```
mkectl apply -f mke4.yaml
```