Simple ingress from host with microk8s?

问题:

I would like to do two things with MicroK8s:

1. Route the host machine (Ubuntu 18.04) ports 80/443 to Microk8s
2. Use something like the simple ingress defined in the kubernetes.io docs

My end goal is to create a single node Kubernetes cluster that sits on the Ubuntu host, then using ingress to route different domains to their respective pods inside the service.

I've been attempting to do this with Microk8s for the past couple of days but can't wrap my head around it.

• The best I've gotten so far is using MetalLB to create a load balancer. But this required me to use a free IP address available on my local network rather than the host machines IP address.

• I've also enabled the default-http-backend and attempted to export and edit these config files with no success.

As an example this will work on Minikube once the ingress add on is enabled, This example shows the base Nginx server image at port 80 on the cluster IP:

# ingress-service.yaml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-service
  annotations:
    kubernetes.io/ingress.class: nginx
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
    # - host: nginx.ioo
    - http:
        paths:
          - path: /
            backend:
              serviceName: nginx-cluster-ip-service
              servicePort: 80

# nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  replicas: 1
  selector:
    matchLabels:
      component: nginx
  template:
    metadata:
      labels:
        component: nginx
    spec:
      containers:
        - name: nginx
          image: nginx
          ports:
            - containerPort: 80

# nginx-cluster-ip-service

apiVersion: v1
kind: Service
metadata:
  name: nginx-cluster-ip-service
spec:
  type: ClusterIP
  selector:
    component: nginx
  ports:
    - port: 80
      targetPort: 80

回答1:

If I understood you correctly, there are a few ways you might be looking at.

One would be MetalLB which you already mentioned.

MetalLB provides a network load-balancer implementation for Kubernetes clusters that do not run on a supported cloud provider, effectively allowing the usage of LoadBalancer Services within any cluster.

You can read the detailed implementation A pure software solution: MetalLB

Another way would be Over a NodePort Service

This approach has a few other limitations one ought to be aware of:

• Source IP address

Services of type NodePort perform source address translation by default. This means the source IP of a HTTP request is always the IP address of the Kubernetes node that received the requestfrom the perspective of NGINX.

You can also use host network

In a setup where there is no external load balancer available but using NodePorts is not an option, one can configure ingress-nginx Pods to use the network of the host they run on instead of a dedicated network namespace. The benefit of this approach is that the NGINX Ingress controller can bind ports 80 and 443 directly to Kubernetes nodes' network interfaces, without the extra network translation imposed by NodePort Services.

You have to also remember that if you edit the configuration inside the POD, it will be gone if the Pod is restarted or it crashes.

I hope this helps you to determine which way to go with your idea.

回答2:

When using a LoadBalancer (aka metallb) there is an important step missing in almost all docs:

The ingress-controller needs to be exposed to the metallb LoadBalancer.

kubectl expose deploy nginx-deployment --port 80 --type LoadBalancer

This can be done by a yaml as well but its way easier to use the cli.

After days of googling i finally came across this tutorial video that opened my eyes.

https://www.youtube.com/watch?v=xYiYIjlAgHY