What free in-depth video course, article series or book would you recommend to learn kubernetes?

The goal is to get to junior devops level of expertise, so I'm not talking about 'learn k8s in one hour crash course'.

Intro to k8s in the Linux foundation are good but pricy.

Udemy has some good courses for 1/10 the price.
There I have hear this guy is good.

That is if you specifically want courses. I like the tests so I can test my knowledge. Another option is of course the documentation and maybe Anki cards. There are decks already created based on the certification from the first link.

Lots of these around, been following this slowly

https://github.com/DevCloudNinjas/DevOps-Projects/tree/master/learning/kubernetes-learning-path

Dive in. Ubuntu has microk8s which is ridiculously easy to install and run. Don't use helm charts. Start with just understanding how to deploy pods and services. Searx can be very easy to get started with since it doesn't have any database or volume requirements - just the application itself.

https://kubernetes.io/docs/
Just start with the official docs (not joking).

Tutorials, Concepts, and Tasks sections are detailed enough for basic cluster deployment and management.

Also the API reference page (https://kubernetes.io/docs/reference/kubernetes-api/) contains a lot of valuable information.

https://training.play-with-kubernetes.com/

https://professionallinuxusersgroup.github.io/course-books/lac/u9intro/ — this course I like quite a lot, it's very in depth about Linux overall, covering containers and kubernetes.

There is also this site: https://killercoda.com/ , which has online interactive environments and tutorials.

For example: https://killercoda.com/het-tanis/course/Kubernetes-Labs

The first course, Introduction to Kubernetes, is free and I found it to be a good foundation to start with.

There are video segments and follow-along style elements.

Main advice I can give is to try and get a general instanding of how the system works rather than worrying about all thr resources types.

Kodekloud has been wonderful. They have all sorts of tiered material, and hands on labs. In my experience, they are second to none. Very affordable pricing as well.