Exposing Services

1. via Ingress

In this example, we will deploy a simple nginx webserver deployment and make it accessible via ingress. Therefore, we have to create the cluster in a way, that the internal port 80 (where the traefik ingress controller is listening on) is exposed on the host system.

1. Create a cluster, mapping the ingress port 80 to localhost:8081

   k3d cluster create --api-port 6550 -p "8081:80@loadbalancer" --agents 2

   Good to know

   • --api-port 6550 is not required for the example to work. It’s used to have k3s‘s API-Server listening on port 6550 with that port mapped to the host system.
   • the port-mapping construct 8081:80@loadbalancer means
     • map port 8081 from the host to port 80 on the container which matches the nodefilter loadbalancer
   • the loadbalancer nodefilter matches only the serverlb that’s deployed in front of a cluster’s server nodes
     • all ports exposed on the serverlb will be proxied to the same ports on all server nodes in the cluster

2. Get the kubeconfig file

   export KUBECONFIG="$(k3d kubeconfig write k3s-default)"

3. Create a nginx deployment

   kubectl create deployment nginx --image=nginx

4. Create a ClusterIP service for it

   kubectl create service clusterip nginx --tcp=80:80

5. Create an ingress object for it with kubectl apply -f Note: k3s deploys traefik as the default ingress controller

   # apiVersion: networking.k8s.io/v1beta1 # for k3s < v1.19
   apiVersion: networking.k8s.io/v1
   kind: Ingress
   metadata:
     name: nginx
     annotations:
       ingress.kubernetes.io/ssl-redirect: "false"
   spec:
     rules:
     - http:
         paths:
         - path: /
           pathType: Prefix
           backend:
             service:
               name: nginx
               port:
                 number: 80
   

6. Curl it via localhost

   curl localhost:8081/

2. via NodePort

1. Create a cluster, mapping the port 30080 from agent-0 to localhost:8082

   k3d cluster create mycluster -p "8082:30080@agent[0]" --agents 2

   • Note: Kubernetes’ default NodePort range is 30000-32767

   • Note: You may as well expose the whole NodePort range from the very beginning, e.g. via k3d cluster create mycluster --agents 3 -p "30000-32767:30000-32767@server[0]" (See this video from @portainer)

… (Steps 2 and 3 like above) …

1. Create a NodePort service for it with kubectl apply -f

   apiVersion: v1
   kind: Service
   metadata:
     labels:
       app: nginx
     name: nginx
   spec:
     ports:
     - name: 80-80
       nodePort: 30080
       port: 80
       protocol: TCP
       targetPort: 80
     selector:
       app: nginx
     type: NodePort
   

2. Curl it via localhost

   curl localhost:8082/

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Last update: November 10, 2020