question

It's likely that you haven't managed to successfully created a KiND cluster. For a bit of background information, KiND (kind) is a tool that allows you to run "local" Kubernetes clusters using Docker container "nodes". It is another Kubernetes project that lets you easily create k8s clusters without having to provision multiple VM instances.

You haven't provided sufficient information above so the best I can do is speculate that when you attempted create a k8s cluster in step 6a, it failed.

You can figure out if one was in fact created with the following command:

$ kind get clusters

If you were successful in creating the k8s cluster, you should see the following output:

$ kind get clusters
kind-cassandra

Note too that you won't be able to run kubectl commands if the Kubernetes master is not running. A quick way to test this is by checking if a Docker process is listening on the master port 45451. In the example below, the process docker-proxy (process ID 2097) is listening the port 45451:

$ sudo lsof -nPi -sTCP:LISTEN
COMMAND    PID            USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
...
docker-pr 2097            root    4u  IPv4 635858      0t0  TCP 127.0.0.1:45451 (LISTEN)

If you want to start over, you can delete your KiND cluster with the following command:

$ kind delete cluster --name kind-cassandra

In relation to this:

Also, please provide some materials/references to get a good insight into dockers and k8s. Something that we can grasp in two hours.

There is no such thing -- Docker on its own is a huge topic, and so is Kubernetes. This workshop is our attempt to give you the basics. For what it's worth, we don't "own" Docker or Kubernetes so you will need to source information on the internet.

Here are some references to get you started:

• Docker - https://www.docker.com/get-started
• Kubernetes - https://kubernetes.io/docs/home/
• KiND - https://kind.sigs.k8s.io/docs/user/quick-start/

Cheers!