Exposing Services¶
1. via Ingress (recommended)¶
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.
-
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 havek3s
‘s API-Server listening on port 6550 with that port mapped to the host system.- the port-mapping construct
8081:80@loadbalancer
means:
“map port8081
from the host to port80
on the container which matches the nodefilterloadbalancer
“- the
loadbalancer
nodefilter matches only theserverlb
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
- all ports exposed on the
- the
-
Get the kubeconfig file (redundant, as
k3d cluster create
already merges it into your default kubeconfig file)export KUBECONFIG="$(k3d kubeconfig write k3s-default)"
-
Create a nginx deployment
kubectl create deployment nginx --image=nginx
-
Create a ClusterIP service for it
kubectl create service clusterip nginx --tcp=80:80
-
Create an ingress object for it by copying the following manifest to a file and applying with
kubectl apply -f thatfile.yaml
Note:
k3s
deploystraefik
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
-
Curl it via localhost
curl localhost:8081/
2. via NodePort¶
-
Create a cluster, mapping the port
30080
fromagent-0
tolocalhost:8082
k3d cluster create mycluster -p "8082:30080@agent[0]" --agents 2
- Note 1: Kubernetes’ default NodePort range is
30000-32767
-
Note 2: 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)- Warning: Docker creates iptable entries and a new proxy process per port-mapping, so this may take a very long time or even freeze your system!
… (Steps 2 and 3 like above) …
- Note 1: Kubernetes’ default NodePort range is
-
Create a NodePort service for it by copying the following manifest to a file and applying 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
-
Curl it via localhost
curl localhost:8082/