DataStax Academy FAQ

DataStax Academy migrated to a new learning management system (LMS) in July 2020. We are also moving to a new Cassandra Certification process so there are changes to exam bookings, voucher system and issuing of certificates.

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question

natrajan.rajasekaran_191958 avatar image
natrajan.rajasekaran_191958 asked ·

Why can't I run "kubectl get nodes" in the week 5 exercise setup?

I worked on the exercises for Cassandra on Kubernetes exercises at https://github.com/DataStax-Academy/cassandra-workshop-series/tree/master/week5-Cass-in-k8s

I tried do it in the cloud environment provided by datastax as well as on my laptop.

1. With cws-week5-k8s set up: I was unable to execute step 6d. It came out with invalid login credentials. I was unable to proceed after that. When I started again the next day, the environme nt was broken. Is it possible to reset the set up? I like to redo all steps till the end. Please provide the steps to reset.

[Second question posted in #7287]

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

workshopcass-operator
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1 Answer

Erick Ramirez avatar image
Erick Ramirez answered ·

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:

Cheers!

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