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Step 1

Play a bit with the pod resource

  • Display a basic pod definition
cat single_pod_basic.yaml

Here you can see basic properties you should define to run a pod with a single container.

First there is the apiVersion which defines the version of the Kubernetes API for the current resource, in our case the Pod. Secondly, we specify the resource name to create kind. The all the metadata like name, namespace, annotations. The last field is spec and here is where the main configuration is done.

Now it is time to create a container for running inside our kubernetes cluster. We have a http server (I know it is not really revolutionary) in the app folder and we should create our image and push it into the registry before use it in the pod.

cd app
docker build -t docker.for.mac.registry:5000/my-awesome-app:0.0.0 .
docker push docker.for.mac.localhost:5000/my-awesome-app:0.0.0

Use localhost for Linux OS

Run the pod and observe the result

kubectl create -f single_pod_basic.yaml
kubectl get pods //Hopefully is should be Running
kubectl logs -f <pod_name> //You should see a message of server listening

Now we can try to test if it works running a pod to query the Node server pod We need to know the IP of the pod

kubectl get pod -o wide

And now we run the temporary pod and make a request to our single pod

kubectl run -i --tty busybox --image=busybox -- sh
wget -qO- <pod_ip>:8080 //You should see the incoming message

Clean our mess

kubectl delete pod,deploy single-pod busybox

Now let's make it more interesting

We build a new app version which it reads a ini configuration file from a volume. Why? because we will have another container with the same volume mounted which will write configuration text. Two containers will shared the volume because they are in the same pod living.

Let's create the new version

cd app_advanced
docker build -t docker.for.mac.localhost:5000/my-awesome-app:0.0.1 .
docker push docker.for.mac.localhost:5000/my-awesome-app:0.0.1
  • Display pod definition a bit more complex
cat single_pod.yaml

So we can observe there are three containers. One with our known app. Second one, which only echo a text and stops. And a curl container we will use to make a request checking the network sharing.

  • Create the pod resource with the three containers inside
kubectl create -f single_pod.yaml
  • List the pod created
kubectl get pod
  • See resource description
kubectl describe po/single-pod
  • Show app container logs
kubectl logs -f single-pod -c my-awesome-app
  • Ssh to curl container and make a request to app container
kubectl exec single-pod -c curl-container -ti sh
curl http://127.0.0.1:8080

Open localhost:8080

  • Delete pod
kubectl delete po single-pod