The MetalLB Operator offers a software network load balancing implementation that allows for LoadBalancing services in Kubernetes.

This Operator deploys a charm bundle to a Juju K8s model. The bundle is composed of the charm metallb-controller and the charm metallb-speaker. These individual charms can be found under the charms/ directory.

Upstream documentation can be found here : https://metallb.universe.tf/

MetalLB has two modes of operation: Layer 2 or BGP. Both concepts are explained here https://ubuntu.com/kubernetes/docs/metallb. This charm currently supports only the layer 2 mode.

Setting up this bundle requires a Kubernetes cluster, either on public cloud, on-premises cloud, or even on a MicroK8s single-node deployment.

You will need to install these snaps to get started: sudo snap install juju --classic sudo snap install microk8s --classic

Next, you will need to add yourself to the microk8s group:

sudo usermod -aG microk8s $USER
newgrp microk8s

Once MicroK8s is installed, you can verify that it is running adequately with: microk8s.status

For Juju to bootstrap a microk8s controller, two addons need to be enabled: microk8s.enable dns storage

Once that is done, you can bootstrap a juju controller: juju bootstrap microk8s

The charm is by default using a layer 2 configuration, and the ip range "192.168.1.240-192.168.1.250". You can use a bundle.yaml config to edit these, or use the juju config command line to edit it post-deployment.

juju add-model metallb-system
juju deploy cs:~charmed-kubernetes/metallb-bundle

juju config metallb-controller iprange=<IPRANGE>

A bundle.yaml would look like this:

description: A charm bundle to deploy MetalLB in Kubernetes
bundle: kubernetes
applications:
  metallb-controller:
    charm: cs:~charmed-kubernetes/metallb-controller
    scale: 1
    options:
      iprange: "192.168.1.88-192.168.1.89" #Change this!
  metallb-speaker:
    charm: cs:~charmed-kubernetes/metallb-speaker
    scale: 1

You would then deploy the bundle by calling this local file: juju deploy ./bundle.yaml

Once deployed, metallb will automatically assign ips from the range given to it to services of type Load Balancer. When the services are deleted, the ips are available again. MetalLB will only use the ips allocated in the pool(s) given to it, and more than one pool can be assigned as well.

To test the usage of metallb, a simple webapp can be deployed. An example manifest is included in this bundle, under docs/example-microbot-lb.yaml. You can use it by copying it locally: #TO-DO: change link once merged under charmed-kubernetes wget https://raw.githubusercontent.com/camille-rodriguez/metallb-bundle/master/docs/example-microbot-lb.yaml microk8s.kubectl apply -f example-microbot-lb.yaml microk8s.kubectl get service microbot-lb

The EXTERNAL-IP is the ip assigned to the microbot service by the MetalLB controller. If you reach this IP with a browser, you should see the image of a microbot. If you cannot, most probably the ip range is not correctly chosen. The ip range needs to be a reserved pool uniquely for metallb, to avoid ip conflicts.

To remove the example, simply delete the manifest with kubectl: microk8s.kubectl delete -f example-microbot-lb.yaml

To remove metallb from the cluster, you can remove each application separately:

juju remove-application metallb-controller
juju remove-application metallb-speaker

or alternatively, you can delete the model itself (be careful, if you deployed additional things in this model, then these things would be deleted as well):

juju remove-model metallb-system

(Valid while this charm is still under Camille Rodriguez's repo) To edit this charm and run it locally to test changes, pull this repo: git clone https://github.com/camille-rodriguez/metallb-bundle.git

To build the charm, simply use tox in the base folder: cd metallb-bundle tox -e build

Edit the bundle.yaml to point to local charms instead of the charmhub. metallb-controller: charm: ./charms/metallb-controller/.build/metallb-controller.charm metallb-speaker: charm: ./charms/metallb-speaker/.build/metallb-speaker.charm

Make sure you have juju bootstrapped to some k8s cluster, and go for it: juju add-model metallb-system juju deploy .