Kubernetes at Home on Raspberry Pi 4, Part 3

Continue from part 2, this is mostly about installing ingress controller. In short, an ingress controller is like a single entry point for all ingress connections into the cluster.

The reason I chose Flannel over other CNIs is that it’s lightweight and not bloated with features. I would like to keep the Pi 4s easy before they are tasked with anything. Same reason I’ll install nginx-ingress-controller to have control with ingress. MetalLB looks a good fit for A Raspberry Pi cluster but I’ll pass at this moment, because this is more like a hobby project, if the load is really high and redundancy is necessary I’ll probably use AWS or GCP which has decent load balancers.

The official nginx-ingress-controller image at quay.io doesn’t seem to support armhf/armv7 architecture, so I built one myself here. To deploy the ingress controller schema but using my own container image, I chose kustomize for the little tweak. (Also kustomize has been integrated into kubectl v1.14+).

First I downloaded the official nginx-ingress-controller schema:

$ wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/mandatory.yaml
$ wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/static/provider/baremetal/service-nodeport.yaml

Then I use kustomize to replace the container image with my own:

$ cat <<EOF >kustomization.yaml
apiVersion: kustomize.config.k8s.io/v1beta1
kind: Kustomization
resources:
  - mandatory.yaml
  - service-nodeport.yaml 
images:
  - name: quay.io/kubernetes-ingress-controller/nginx-ingress-controller
    newName: raynix/nginx-ingress-controller-arm
    newTag: 0.25.1
EOF
# then there should be 3 files in current directory
$ ls
kustomization.yaml  mandatory.yaml  service-nodeport.yaml
# install with kubectl
$ kubectl apply -k .

To see the node port for this ingress controller, do

$ k get --namespace ingress-nginx svc
 NAME            TYPE       CLUSTER-IP     EXTERNAL-IP   PORT(S)                      AGE
 ingress-nginx   NodePort   10.100.0.246           80:32283/TCP,443:30841/TCP   7d14h

In the upstream nginx or HAProxy box, a static route can be set to route traffic to ingress controller:

$ sudo ip route add 10.100.0.0/24 \
  nexthop via <node1 LAN IP> dev <LAN interface> weight 1 \
  nexthop via <node2 LAN IP> dev <LAN interface> weight 1
$ sudo ip route
...
10.100.0.0/24 
     nexthop via 192.168.1.101 dev enp0xxx weight 1 
     nexthop via 192.168.1.102 dev enp0xxx weight 1  
...

To test if the ingress controller is visible from the upstream box, do

$ curl -H "Host: nonexist.com" http://10.100.0.246
<html>
<head><title>404 Not Found</title></head>
<body>
<center><h1>404 Not Found</h1></center>
<hr><center>openresty/1.15.8.1</center>
</body>
</html>

Now the ingress controller works 🙂

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