Review of Kubernetes Practice Labs
While studying for the Certified Kubernetes Administrator certification last year, I wanted to take a deep dive into Kubernetes topics, both those covered by the certification and beyond.
As a develeap employee, I had access to all of develeap’s courses which I used to learn more about Kubernetes. Alongside that, I wanted to supplement my learning with books and practice labs. After I earned the CKA certification, I decided to review the field of Kubernetes books and practice labs. In part one of this article series, I reviewed several of the books and written materials that I have read while learning about Kubernetes “The Ultimate Guide to Kubernetes Books: From Beginner to Certified Expert”. In this part, I reviewed Kubernetes practice labs and mock exams.
Killercoda
Link: Killercoda CKA Area
CKAD Equivalent: Killercoda CKAD Area
Killercoda offers free labs! Although Killercoda does offer subscriptions, the paid features which are currently included are not major. I’d say the main reason to consider a subscription is if you are using Killercoda frequently and want to support what they are doing. Honestly, what they are doing is excellent and worth supporting.
With a free account you can access various different environments and scenarios. The ones offered are very good and worth doing. I especially like the CKA Playground environment, designed to be similar to the current environment used by the CKA exam. You can use the Killecoda playgrounds to freely play around with Kubernetes, without being constrained to a specific scenario. This is really useful, for example if you just want to try out some commands to see what they do.
In addition, the environments load fast. This is impressive considering this is all available on the free tier.
Killer Shell
Link: Killer Shell CKA Simulator
CKAD Equivalent: Killer Shell CKAD Simulator
Killer Shell is created and maintained by the same team as Killercoda (led by Kim Wüstkamp), however they have notable differences. You can read their own comparison here; to summarize, while Killercoda allows you to practice exam topics, it is not an exam simulator.
Killer Shell is an exam simulator. In fact, it is the official exam simulator for the CKA, CKAD and CKS certifications (and soon the LFCT certification as well). Although using Killer Shell on its own is not free, you get two sessions included when signing up for any of these certifications.
Each session lasts 36 hours and includes an exam simulation that is designed to closely mirror the real exam environment. This means you get not only a terminal, but also a full XFCE desktop to work in. You get to work on 25 questions (plus a few extra questions) across several different Kubernetes clusters. You have a two-hour timer. However, after the two hours pass, you can continue to answer the questions at your own pace (up to the 36-hour time limit of the session).
To be honest, it’s very hard to answer all 25 questions within the two-hour limit… The questions in the Killer Shell exam are designed to be slightly harder than in the real exam. In addition, in the real exam, you are likely to get less than 25 questions to answer within the two-hour limit. My advice is not to focus too heavily on the time limit. However, do make sure you can answer all questions, even if it takes you longer than two hours. Nevertheless, you should be trying to find ways in which you can work fast and most efficiently; for example setting aliases and environment variables, and learning Vim shortcuts. These tricks will help you in the real exam, and the exam simulation is the best place to practice.
After the two-hour timer passes (which you can also end early), you get to see an automated scoring system that checks which questions you answered correctly. The exam, however, still continues in the background, and you can go back to questions and fix your answers. I noticed the automated scoring system sometimes takes a few minutes to update, which led to some confusing situations where I tried to fix an answer but had to wait a few minutes to confirm I answered correctly. Another nitpick is the automated scoring system is a bit overly strict in the way it likes its answers. For example, in one of the early questions, you have to write a shell script to do a simple task; this can be done in several ways, but in practice, the script has to be written in the exact way that the automated scoring system expects (you can’t even use a shebang, as a friend of mine found out while trying out Killer Shell). I don’t know if the real exam is as strict with its scoring as Killer Shell. ^2
In the real CKA exam you don’t get to see which questions you answered correctly, that’s why you should practice checking your own answers. After answering questions, you should verify that you did things correctly using different commands. Again this is something which of course can be practiced within the Killer Shell environment.
As I mentioned, you get two Killer Shell sessions after signing up for a certification. It’s worth noting that both sessions will have the same questions. In my case I found that one session was sufficient for preparing for the real exam. However if you didn’t do well in the first session, then that’s a good sign you should go back to practice and learn the concepts that you struggled with. Once you are able to get a good score at Killer Shell, you will know you are ready for the exam.
As for when to take the Killer Shell exam, it is often recommended to take it relatively close to the real exam (say within one week), after you have thoroughly learned using other resources. If you are already experienced in using Kubernetes and wondering if you need to spend time on courses, you could test yourself by doing a Killer Shell simulation session first and see how well you do.