CKA certification notes - CKA certification experience post

Recently CKA I passed the certification , Briefly summarize the examination experience , Hope to be helpful to students in need .

One . To sign up & make an appointment

1. To sign up

The registration address is https://www.cncf.io/certification/cka/, You can choose Chinese or English to sign up , I choose English .

There are several discount codes for English registration ：KUBERNETES15、DEVOPS15, Can play 85 fold , Close test available .

Enter the payment interface and pay .

2. make an appointment

After the payment is completed, you will receive an email , Get into

Click on 「View Your Portal」 Or visit directly https://trainingportal.linuxfoundation.org/learn/dashboard You can see the exam items .

Click the button on the right to enter the appointment interface , There will be a series of checklist
Including installing plug-ins , Agree to the agreement and other operations , In a few minutes after it's all finished 「 Appointment button 」 Will be available , Click to make an appointment , Note that the default time zone of the appointment is UTC, First choose Beijing time and then make an appointment .

You will receive an email after the appointment , The next step is to wait for the exam .

Two . Exam introduction & Suggestions for preparation

1. Introduction to examination outline

CKA The examination mainly includes the following items ：

For detailed examination outline, see CKA_Curriculum.

• notes ：2020 year 9 month 1 After number , Test cluster version changed to 1.19, And reduce safety related content , Moved it to the upcoming CKS In the exam , But I will still investigate RBAC Related content .

2. Examiner check items

Before the exam 15 There will be a remote examiner to do a series of examinations in minutes , If it's a morning exam, I suggest setting aside time , Avoid network problems or being disturbed when the exam starts too late .

The inspection mainly includes the following items ：

1. Turn on camera & Computer desktop sharing

First, the examiner will ask you to turn on the camera , Close irrelevant processes and share the computer desktop , If there is an external display, it also needs to be shared .

2. Check the desk & Room environment

After the camera is turned on , The examiner will guide us to do a series of operations , For example, check the computer process 、 Check the browser tab、 Check the room environment and office desktop 、 Under the table , Just do it , Pay attention to a few points :

• No one else can be in the middle of the exam , Therefore, try to choose a time not to be disturbed for the exam .
• There must be nothing irrelevant on the desktop , Like books 、 Glass etc. .
• You must always turn on the camera and desktop sharing during the exam , The camera needs to be able to see the whole face all the time , Don't drink water 、 Cover your mouth .

3. Introduction to the examination interface

After the examination, you can enter the examination interface . The examination interface is as follows ：

• picture source ：https://blog.csdn.net/fly910905/article/details/102966474

There is a time bar on the left 、 Language selection and topic description . The topic language can be English 、 Chinese and Japanese , The Chinese translation may be slightly dysfunctional , You can read it in both Chinese and English .

There are other tools in the upper right corner notepad, It can be used to save some commands .

4. Exam advice

Just how I feel after the exam ,CKA The problem is not difficult , But the examination covers a wide range , Will comprehensively investigate the lifecycle management of cluster applications , Dispatch , The Internet , Storage , Cluster operation and maintenance , Cluster troubleshooting and so on .

The length of the exam 2 Hours , Yes 15 ~ 20 questions . When I took the exam 17 Avenue . Each topic will give the required environment 、 Title Requirements and weight , The weight adds up to 100 branch , exceed 66 Even if it's divided . You can flexibly choose the order of doing questions according to the weight and familiarity of knowledge points .

Here are some exam suggestions ：

【1】 Get ready VPN

After all, foreign examinations , Network problems still need to be considered , It is recommended to take the exam in the morning or late at night , And get ready VPN. I took the exam at six in the morning , There is basically no dullness in tapping the command line with feed pin .

【2】 Quickly browse the topic

It is suggested to browse all the topics first , Aim at what you want . Some topics, such as revision deployment Of replica It takes only a few tens of seconds to count an order , The cluster upgrade needs to wait for the relevant software installation 、 Only after the upgrade of cluster components is completed , Therefore, you can flexibly adjust the order of doing questions according to the examination time .

【3】 Pay attention to the context required by the topic

The exam will be given to several clusters , I have 7 individual , Different topics will be required to be completed in different clusters ,

The corresponding cluster name and switching command will be given at the beginning of each topic , Therefore, you must implement it in advance to ensure that the environment for doing questions is correct .

【4】 Enable kubectl Automatic prompt

Many materials on the Internet say that the examination environment has been configured with automatic prompts , But I didn't have it in the exam , You need to set up your own ：
The document address is enabling-shell-autocompletio, You can collect it in advance and directly open it for copying .

【5】 Organize the document collection in advance

For some simple operations , Like upgrading Deployment Mirror image , Try to complete horizontal expansion with commands . If you need to write yaml The title of the document , Such as creating Ingress、Network Policy、PV/PC,RABC etc. , Hand tapping is too slow , You can first copy it from the official document to modify , To save time , You can organize the corresponding document address into favorites , Just open it when you need it .

3、 ... and . Short notes of exam questions

Here are the questions I sorted out after the exam , You can use it as a reference .

1 . establish ServiceAccount And create Deployment Authority .

• Reference documents ：Using RBAC Authorization
• Reference documents ：Certificate Signing Requests
  , CSR Maybe not

2 . etcd Data backup and recovery

• Reference documents : kubernetes-the-hard-way

3 . Deployment Horizontal expansion of

• Reference documents Scaling a Deployment

4 . be based on nodeSelector Dispatch Pod

• Reference documents ：Assigning Pods to Nodes

5. see log journal

The subject is very simple , Generally, it is to check a Pod And then output it to a file ：

kubectl logs -f PodNmae [containerName]| grep "" > file

6. see Pod Of CPU Use

Generally, it has been installed metric server, Direct use kubectl top Just check the command .

7 . Create a multi container as required Pod

8. by Pod establish NodeType Type of Service

• Reference documents ：Service

9. According to the specified path and Service establish Ingress

• Reference documents ：Ingress

10 . Create according to the specified rules NetworkPolicy

• Reference documents :NetworkPolicy

11. Create according to the specified conditions PV、PVC And mount Pod, After the modification PVC The capacity of

• Reference documents ：Configure a Pod to Use a PersistentVolume for Storage
• Reference documents ：Persistent Volumes

12 . To the existing Pod add to sidecar Container to collect logs

• Reference documents ：sing a sidecar container with the logging agent

13. Upgrade master

Visual inspection of cluster upgrade is a must , You need to see whether to upgrade the master node or worker node , The steps are generally ：

• View upgrade information :kubeadm upgrade plan

• Expel the corresponding node kubectl drain nodeName

• upgrade kubeadm apt-get install kubeadm=1.19.0-00

• Perform cluster upgrade

  • Upgrade master kubeadm upgrade apply v1.19.3
  • upgrade worker node ：kubeadm upgrade node

• upgrade kubelet: apt-get install kubeamd=1.19.0-00

• Re enable the node after completion kubectl uncordon nodeName

• Reference documents ：Upgrading kubeadm clusters

14. Evict a node and reschedule

15 . Together taint Related topics , I forgot the details

• Reference documents ：Taints and Tolerations

16. Cluster troubleshooting , Some worker The node is in NotReady, Find out the cause and recover

This is my last question in the exam , The weight 13%, But the topic is not difficult , as a result of worker Node kubelet Has not started ,ssh Log in to worker Node usage systemctl Just start up .

Here are some tip:

• Node problem ：
  • api-server、etcd、scheduler、controller Startup successful , Check /etc/kubernetes/manifests/ Under the yaml Is there a problem with the file .
  • Check whether the network plug-in is installed
  • Check kube-proxy Whether the configuration is correct
  • Check DNS Whether the configuration is correct
  • Check kubelet Whether it starts normally
• Application problems ：
  • Whether the application image is correct
  • Application configured Service、Ingress Whether etc is correct
  • CPU、 Whether the memory and other configurations

Four . Reference materials are recommended

If it's for the exam , Wall crack recommendation Udemy Curriculum Certified Kubernetes Administrator (CKA) with Practice Tests, This is aimed at CKA Certification of tailor-made courses , And with a large number of exercises , After finishing these exercises according to the knowledge points of the course, there is basically no problem in the exam . Here, we need to pay attention to the problem exercise, which requires Vivian , Be prepared in advance .

But my personal feeling CKA The difficulty of the exam is limited , It is not recommended to take an exam for the sake of exam , The important thing is to take advantage of the opportunity of examination to study systematically and deeply K8S, The following is my recent concentrated study K8S Some of the materials , You can use it as a learning reference ：

• 《Kubernetes In Action》
• 《Kubernetes Patterns》
• Geek hour 《 In depth analysis of Kubernetes》
• 《kubernetes-best-practices》

And, of course, the most important Official documents .

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