Kubernetes in a Pod

KIND (Kuberntes in Docker) is very useful when you only need to create a cluster for testing or education purposes. If you provide them in a Pod, you can easily provide kubernetes clusters for many developers or operators for debugging/education/testing purposes.

Create following pod firstly:

kubectl apply -f https://raw.githubusercontent.com/uengine-oss/kubernetes-in-pod/master/kind-cluster.yaml

After creating the Pod, attach to the bash:

kubectl exec -it kind-cluster -- /bin/bash

Wait until the Kind cluster is up by trying to set the Kubectl context connect to the Kind:

root@kind-cluster:/# kubectl cluster-info --context kind-kind  # try this for about 2~3 minutes
error: context "kind-kind" does not exist

.... after 2~3 minutes .... 

root@kind-cluster:/# kubectl cluster-info --context kind-kind

Kubernetes master is running at https://10.36.10.137:30001
KubeDNS is running at https://10.36.10.137:30001/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To access the service outside the pod, you need to install NGINX Ingress Provider firstly:

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/main/deploy/static/provider/kind/deploy.yaml

Alternatively, Ambassador Ingress Provider can be used on behalf of the NGINX:

kubectl apply -f https://github.com/datawire/ambassador-operator/releases/latest/download/ambassador-operator-crds.yaml
kubectl apply -n ambassador -f https://github.com/datawire/ambassador-operator/releases/latest/download/ambassador-operator-kind.yaml
kubectl wait --timeout=180s -n ambassador --for=condition=deployed ambassadorinstallations/ambassador    # skippable

Create an Ingress for accessing the service:

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: example-ingress
spec:
  rules:
  - host: "www.service.com"
    http:
      paths:
      - path: "/"
        backend:
          serviceName: <service name>
          servicePort: 80

After that, we need to annotate the Ingress so that the Ambassador pick up the service to it's operator:

kubectl annotate ingress example-ingress kubernetes.io/ingress.class=ambassador

Make sure that you have to configure the hosts file before you access to the URL www.service.com:

# vi /etc/hosts

<the external ip obtained from kind-cluster service>   www.service.com   

You can get the external ip by hitting:

# kubectl get svc kind-cluster
NAME                                            TYPE           CLUSTER-IP      EXTERNAL-IP     PORT(S)                       AGE
kind-cluster                                    LoadBalancer   10.101.3.24     34.146.166.15   80:31357/TCP,3000:32749/TCP   16h

If you use Istio, you only need to expose the istio-ingressgateway:

To install istio, follow the instruction: https://istio.io/latest/docs/setup/getting-started/

apiVersion: networking.k8s.io/v1beta1
kind: Ingress
metadata:
  name: example-ingress
  namespace: istio-system
spec:
  rules:
  - host: "www.service.com"
    http:
      paths:
      - path: "/"
        backend:
          serviceName: istio-ingressgateway
          servicePort: 80

And annotate the ingress to make effect for Ambassador:

kubectl annotate ingress example-ingress kubernetes.io/ingress.class=ambassador -n istio-system      # for istio-system

Finally, go to following URL with a browser:

www.service.com/<service paths>

Example configuration for istio and istio-related telemetry services:

kubectl apply -f https://raw.githubusercontent.com/uengine-oss/kubernetes-in-pod/master/ingress-istio.yaml

• /etc/hosts file

34.146.166.15   www.service.com
34.146.166.15   tracing.service.com
34.146.166.15   grafana.service.com

RoadMap

Integration with Theia-IDE, for providing an integrated development environment for complete kubernetes development.