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Networking

Networking is a very important part of any cluster.
For our purposes, we will be configuring K3s with a load balancer thats distributed across the nodes, instead of relying on an external load balancer, which isn't as common in a home setting.

Key concept​

Deployment -> Service -> Ingress Rule.

Deployment​

A deployment, pod or container is what you application is.

Service​

Your service is what points at that object (we'll go over the config for this later), and allows you to spin up/down the deployment without reconfiguring. Think of it like another load balancer, just for your application.
This will be 'pointed' at your deployment selectors.

Ingress​

This is what tells your ingress-controller, in this case Traefik, what to point DNS names at.
This will be 'pointed' at your service.

Step 1 - Install MetalLB​

We need to install MetalLB, which will be our Kubernetes hosted load balancer.
Run the following commands from your admin workstation - 

kubectl apply -f https://raw.githubusercontent.com/metallb/metallb/v0.13.7/config/manifests/metallb-native.yaml

Configure MetalLB Secrets (Optional)​

We can also configure MetalLB to secure its communications behind a secret.
You can run the following command to set this - 

kubectl create secret generic -n metallb-system memberlist --from-literal=secretkey="$(openssl rand -base64 128)"

Configure MetalLb IP Range​

Next we need to tell MetalLB what IPs from your local LAN it can use and allocated.

Create a new file called metallb_config.yaml, and copy the below into it. 

---
apiVersion: metallb.io/v1beta1
kind: IPAddressPool
metadata:
  name: default
  namespace: metallb-system
spec:
  addresses:
  - 192.168.0.230/32

At the bottom, adjust your address range, or ranges if you want, that MetalLB can use. Next, apply it to MetalLB - 

kubectl apply -f metallb_config.yaml
tip

We can add additional address-pools to this configuration for MetalLB, giving us the ability to 'point' different load balancers at different pools, dependant on what we want them to do/their use. Just add in another - name block, and give it a unique name.
You can also specify individual IPs by using its CIDR notation.

Next Step​

Next, go to the next step, Storage.
Or,
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