Kubernetes CKA真题解析-20200402真题

1.日志 kubectl logs监控 foobar Pod 的日志，提取 pod 相应的行’error’写入到/logs 文件中Set configuration context $ kubectl config use-context k8s Monitor the logs of Pod foobar andExtract log lines corresponding to er...

思想者0001

13848人浏览 · 2020-05-01 20:01:12

思想者0001 · 2020-05-01 20:01:12 发布

1.日志 kubectl logs

监控 foobar Pod 的日志，提取 pod 相应的行’error’写入到/logs 文件中

Set configuration context $ kubectl config use-context k8s Monitor the logs of Pod foobar and
	Extract log lines corresponding to error file-not-found
	Write them to /opt/KULM00201/foobar

  kubectl logs foobar | grep file-not-found > /logs

2.输出排序 --sort-by=.metadata.name

使用 name 排序列出所有的 PV，把输出内容存储到/opt/文件中使用 kubectl own 对输出进行排序，并且不再进一步操作它

List all PVs sorted by name saving the full kubectl output to /opt/KUCC0010/my_volumes . Use kubectl’s own functionally for sorting the output, and do not manipulate it any further.

  kubectl get pv --all-namespace --sort-by=.metadata.name > /opt/

3.ds部署

确保在 kubectl 集群的每个节点上运行一个 Nginx Pod。其中 Nginx Pod 必须使用 Nginx 镜像。不要覆盖当前环境中的任何 traints。使用 Daemonset 来完成这个任务，Daemonset 的名字使用 ds。

Ensure a single instance of Pod nginx is running on each node of the kubernetes cluster where nginx also represents the image name which has to be used. Do no override any taints currently in place.

Use Daemonsets to complete this task and use ds.kusc00201 as Daemonset name

题目对应文档：https://kubernetes.io/docs/concepts/workloads/controllers/daemonset/
删除tolerations字段，复制到image: gcr.io/fluentd-elasticsearch/fluentd:v2.5.1这里即可，再按题意更改yaml文件。
apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: ds
  namespace: kube-system
  labels:
	k8s-app: fluentd-logging
spec:
  selector:
	matchLabels:
	  name: fluentd-elasticsearch
  template:
	metadata:
	  labels:
		name: fluentd-elasticsearch
	spec:
	  containers:
	  - name: fluentd-elasticsearch
		image: nginx

4.initContainers

添加一个 initcontainer 到 lum(/etc/data)这个 initcontainer 应该创建一个名为/workdir/calm.txt 的空文件，如果/workdir/calm.txt 没有被检测到，这个 Pod 应该退出

	Add an init container to lumpy--koala (Which has been defined in spec file /opt/kucc00100/pod-spec-KUCC00100.yaml)
	The init container should create an empty file named /workdir/calm.txt
	If /workdir/calm.txt is not detected, the Pod should exit
	Once the spec file has been updated with the init container definition, the Pod shou
ld be created.

- 题目中yaml文件已经给出，只需要增加initcontainers部分，以及emptyDir: {} 即可
  init文档位置：https://kubernetes.io/docs/concepts/workloads/pods/init-containers/
  在最后加上
```
initContainers:
- name: init-poda
  image: busybox
  command: ['sh','-c','touch /workdir/clam.txt']
volumeMounts:
- name: workdir
  mountPath: "/workdir"
```

5.多容器

创建一个名为 kucc 的 Pod,其中内部运行着 nginx+redis+memcached+consul 4 个容器

Create a pod named kucc4 with a single container for each of the following images running inside (there may be between 1 and 4 images specified): nginx + redis + memcached + consul

参考链接：
https://v1-14.docs.kubernetes.io/docs/concepts/workloads/pods/pod-overview/

	apiVersion: v1
	kind: Pod
	metadata:
	  name: kucc
	spec:
	  containers:
	  - name: nginx
		image: nginx
	  - name: redis
		image: redis
	  - name: memcached
		image: memcached
	  - name: consul
		image: consul

6.nodeSelector

创建 Pod，名字为 nginx，镜像为 nginx，部署到 label disk=ssd的node上

Schedule a Pod as follows:
	Name: nginx-kusc00101
	Image: nginx
	Node selector: disk=ssd

https://kubernetes.io/docs/concepts/configuration/assign-pod-node/
apiVersion: v1
	kind: Pod
	metadata:
	  name: nginx
	  labels:
		env: test
	spec:
	  containers:
	  - name: nginx
		image: nginx
		imagePullPolicy: IfNotPresent
	  nodeSelector:
		disk: ssd

7.deployment升级和回退（set image --record rollout undo）

创建 deployment 名字为 nginx-app 容器采用 1.11.9 版本的 nginx 这个 deployment 包含 3 个副本,接下来通过滚动升级的方式更新镜像版本为 1.12.0，并记录这个更新，最后，回滚这个更新到之前的 1.11.9 版本

Create a deployment as follows
	Name: nginx-app
	Using container nginx with version 1.10.2-alpine
	The deployment should contain 3 replicas
Next, deploy the app with new version 1.13.0-alpine by performing a rolling update and record that update.
Finally, rollback that update to the previous version 1.10.2-alpine

kubectl run deployment nginx-app --image=nginx:1.11.9 --replicas=3
kubectl set image deployment nginx-app nginx-app=nginx:1.12.0 --record  (nginx-app container名字)
kubectl rollout history deployment nginx-app
kubectl rollout undo deployment nginx-app

8.NodePort

创建和配置 service，名字为 front-end-service。可以通过 NodePort/ClusterIp 开访问，并且路由到 front-end 的 Pod 上

Create and configure the service front-end-service so it’s accessible through NodePort and routes to the existing pod named front-end

kubectl expose pod fron-end --name=front-end-service --port=80  --type=NodePort

9.namespace

创建一个 Pod，名字为 Jenkins，镜像使用 Jenkins。在新的 namespace website-frontend 上创建Pod

 Create a Pod as follows:
	Name: jenkins
	Using image: jenkins
	In a new Kubenetes namespace named website-frontend

kubectl create ns website-frontend

apiVersion: v1
kind: Pod
metadata:
  name: Jenkins
  namespace: website-frontend
spec:
  containers:
  - name: Jenkins
	image: Jenkins
	
kubectl apply -f ./xxx.yaml

10.kubectl run ${deploy-name} --image=’’ --lables=’’ --dry-run -o yaml

创建 deployment 的 spec 文件: 使用 redis 镜像，7 个副本，label 为 app_enb_stage=dev deployment 名字为 kual00201 保存这个 spec 文件到/opt/KUAL00201/deploy_spec.yaml完成后，清理(删除)在此任务期间生成的任何新的 k8s API 对象

Create a deployment spec file that will:
	Launch 7 replicas of the redis image with the label: app_env_stage=dev
	Deployment name: kual0020
Save a copy of this spec file to /opt/KUAL00201/deploy_spec.yaml (or .json)
When you are done, clean up (delete) any new k8s API objects that you produced during this task

kubectl run kual00201 --image=redis --labels=app_enb_stage=dev --dry-run -oyaml > /opt/KUAL00201/deploy_spec.yaml

11.根据service的selector查询pod

创建一个文件/opt/kucc.txt ，这个文件列出所有的 service 为 foo ,在 namespace 为 production 的 Pod,这个文件的格式是每行一个 Pod的名字

Create a file /opt/KUCC00302/kucc00302.txt that lists all pods that implement Service foo in Namespace production.
The format of the file should be one pod name per line

kubectl get svc -n production --show-labels | grep foo

kubectl get pods -l app=foo(label标签)  | grep -v NAME | awk '{print $1}' >> /opt/KUCC00302/kucc00302.txt

12.secret挂载

创建一个secret,名字为super-secret包含用户名bob,创建pod1挂载该secret，路径为/secret，创建pod2，使用环境变量引用该secret，该变量的环境变量名为ABC

Create a Kubernetes Secret as follows:
	Name: super-secret
	Credential: alice  or username:bob 
Create a Pod named pod-secrets-via-file using the redis image which mounts a secret named super-secret at /secrets
Create a second Pod named pod-secrets-via-env using the redis image, which exports credential as TOPSECRET

https://kubernetes.io/zh/docs/concepts/configuration/secret/#%E8%AF%A6%E7%BB%86
echo -n "bob" | base64

apiVersion: v1
kind: Secret
metadata:
  name: super-secret
type: Opaque
data:
  username: Ym9i
  
apiVersion: v1
kind: Pod
metadata:
  name: pod1
spec:
containers:
- name: mypod
  image: redis
  volumeMounts:
- name: foo
  mountPath: "/secret"
  readOnly: true
volumes: secret
- name: foo
  secret:
    secretName: super-secret


apiVersion: v1
kind: Pod
metadata:
  name: pod-evn-eee
spec:
containers:
- name: mycontainer
image: redis
env:
- name: ABC
    valueFrom:
      secretKeyRef:
        name: super-secret
        key: username
restartPolicy: Never

13.emptyDir

创建一个pod，名为non-presistent-redis,挂载存储卷，卷名为：cache-control，挂载到本地的：/data/redis目录下，在名称空间pre-prod里做，不要以持久卷方式挂载。

Create a pod as follows:
	Name: non-persistent-redis
	Container image: redis
	Named-volume with name: cache-control
	Mount path: /data/redis
It should launch in the pre-prod namespace and the volume MUST NOT be persistent.

答案：   没有明确要求挂载在node主机上的具体位置，使用随机位置emptyDir:{} ,如果明确挂载到主机的指定位置和地址，则使用hostPath.
1。创建pre-prod名称空间
kubectl create ns pre-prod
2.创建yaml文件，如下：
apiVersion: v1
kind: Pod
metadata:
  name: non-presistent-redis
  namespace: pre-prod
spec:
  containers:
  - image: redis
    name: redis
    volumeMounts:
    - mountPath: /data/redis
      name: cache-control
  volumes:
  - name: cache-control
    emptyDir: {}

14.deploy scale

为给定deploy 副本扩容到6

 kubectl scale deployment website --replicas=6

15.统计可调度node数

查看给定集群ready的node个数(不包含NoSchedule)

Check to see how many nodes are ready (not including nodes tainted NoSchedule) and write the number to /opt/nodenum

1.kubectl get node | grep -w  Ready | wc -l          ####grep -w是精确匹配
通过上面命令取得一个数N
2.通过下面命令取得一个数M
kubectl describe nodes | grep Taints | grep -I noschedule | wc -l
3.答案填写N减去M得到的值

16.kubectl top

找出指定ns中使用cup最高的pod名写出到指定文件

From the Pod label name=cpu-utilizer, find pods running high CPU workloads and write the name of the Pod consuming most CPU to the file /opt/cpu.txt (which already exists)

kubectc top pod -l name=cpu-utilizer --namespace=xxx

17.svc dns

创建一个 deployment 名字为:nginx-dns 路由服务名为：nginx-dns 确保服务和 pod 可以通过各自的 DNS 记录访问容器使用 nginx 镜像，使用 nslookup 工具来解析 service 和 pod 的记录并写入相应的/opt/service.dns 和/opt/pod.dns 文件中，确保你使用 busybox:1.28 的镜像用来测试。

 Create a deployment as follows
	Name: nginx-dns
	Exposed via a service: nginx-dns
	Ensure that the service & pod are accessible via their respective DNS records
	The container(s) within any Pod(s) running as a part of this deployment should use the nginx image
Next, use the utility nslookup to look up the DNS records of the service & pod and write the output to /opt/service.dns and /opt/pod.dns respectively.
Ensure you use the busybox:1.28 image(or earlier) for any testing, an the latest release has an unpstream bug which impacts thd use of nslookup.

busybox这里找：https://kubernetes.io/docs/concepts/services-networking/dns-pod-service/

第一步：创建deployment
kubectl run nginx-dns --image=nginx
第二步：发布服务
kubectl expose deployment nginx-dns --name=nginx-dns --port=80 --type=NodePort
第三步：查询podIP
kubectl  get pods -o wide (获取pod的ip)  比如Ip是：10.244.1.37 
第四步：使用busybox1.28版本进行测试
kubectl run busybox -it --rm --image=busybox:1.28 sh
\#:/ nslookup nginx-dns     #####查询nginx-dns的记录
\#:/ nslookup 10.244.1.37  #####查询pod的记录
第五步：
把查询到的记录，写到题目要求的文件内，/opt/service.dns和/opt/pod.dns
\####这题有疑义，干脆把查到的结果都写进去，给不给分靠天收，写全一点。
1。nginx-dns的
echo 'Name: nginx-dns' >> /opt/service.dns
echo 'Address 1: 10.96.0.10 kube-dns.kube-system.svc.cluster.local' >> /opt/service.dns
2。pod的
echo 'Name:      10.244.1.37' >> /opt/pod.dns
echo 'Address 1: 10.244.1.37 10-244-1-37.nginx-dns.default.svc.cluster.local' >> /opt/pod.dns

18.etcd备份

etcd，给定https地址，ca，cert证书，key备份数据到指定目录

Create a snapshot of the etcd instance running at https://127.0.0.1:2379 saving the snapshot to the file path /data/backup/etcd-snapshot.db
The etcd instance is running etcd version 3.1.10
The following TLS certificates/key are supplied for connecting to the server with etcdctl
	CA certificate: /opt/KUCM00302/ca.crt
	Client certificate: /opt/KUCM00302/etcd-client.crt
	Clientkey:/opt/KUCM00302/etcd-client.key

ETCDCTL_API=3 etcdctl --endpoints=https://127.0.0.1:2379  --cacert=ca.pem --cert=server.pem --key=server-key.pem  snapshot save 给的路径

有些题目会报错，记得看etcdctl -h 里的字段怎么要求的

19.node维护（drain、cordon、uncordon）

在ek8s集群中使name=ek8s-node-1节点不能被调度，并使已被调度的pod重新调度

Set the node labelled with name=ek8s-node-1 as unavailable and reschedule all the pods running on it.

先切换集群到ek8
kubectl get nodes -l name=ek8s-node-1
kubectl drain wk8s-node-1  
#当目标node上有daementSet时需要加以下参数，所以建议加上
#--ignore-daemonsets=true --delete-local-data=true --force=true

错误类似：
error: DaemonSet-managed pods (use --ignore-daemonsets to ignore): ds.kusc00201-cqcpl, node-exporter-fk7pg

20.node notReady

给定集群中的一个node未处于ready状态，解决该问题并具有持久性

A Kubernetes worker node, labelled with name=wk8s-node-0 is in state NotReady . Investigate why this is the case, and perform any appropriate steps to bring the node to a Ready state, ensuring that any changes are made permanent.

进入集群
kubectl get nodes | grep NotReady
ssh node  
systemctl status kubelet
systemctl start kubelet   
systemctl enable kubelet

21.static pod --pod-manifest-path

题目很绕，大致是在k8s的集群中的node1节点配置kubelet的service服务，去拉起一个由kubelet直接管理的pod(说明了是静态pod)

Configure the kubelet systemd managed service, on the node labelled with name=wk8s-node-1, to launch a Pod containing a single container of image nginx named myservice automatically. Any spec files required should be placed in the /etc/kubernetes/manifests directory on the node.

该文件应该放置在/etc/kubernetes/manifest目录下(给出了pod路径)
	  1.vi /etc/kubernetes/manifest/static-pod.yaml
		定义一个POD
      2.systemctl status kubelet   查找kubelet.service路径  
	  3.vi /etc/systemd/system/kubernetes.service   
	  	观察有没有 --pod-manifest-path=/etc/kubernetes/manifest 
	  	没有就加上
	  4.ssh node  sudo -i
	  5.systemctl daemon-reload            systemctl restart kubelet.service
	  6.systemctl enable kubelet
      7.检查  kubectl get pods -n kube-system | grep static-pod 
      	pod名字是service name + node ip
 
#注意kubelet.service路径，可能不是上面路径，可根据命令查看，但是有可能如下：
Drop-In: /lib/systemd/system/rc-local.service.d
           └─debian.conf
这里定义了配置文件，所以如果直接在/etc/systemd/system/kubernetes.service里面添加属性并不生效。
#这部分内容请学习systemctl进行确认

22.集群问题排查

给出了指定的集群，该集群中kubelet.service服务无法正常启动，解决该问题，并具有持久性

 Determine the node, the failing service and take actions to bring up the failed service and restore the health of the cluster. Ensure that any changes are made permanently.
The worker node in this cluster is labelled with name=bk8s-node-0

情形一：kubectl 命令能用 
kubectl get cs 健康检查  看manager-controller  是否ready   
如果不ready   systemctl start kube-manager-controller.service   
情形二：kubectl 命令不能用
2，ssh登陆到bk8 -master-0上检查服务，如master上的4大服务，
api-server/schedule/controllor-manager/etcd
systemctl list-utils-files | grep controller-manager    没有服务
systemctl list-utils-files | grep api-server       没有服务
3,此刻进入/etc/kubernetes/manifest  文件夹中，可以看到api-server.yaml  controller-manager.yaml等4个文件，说明这几个服务是以pod方式提供服务的。
4, systemctl status kubelet     看到是正常启动的，
说明api-server   controlloer-manager    etcd    schedule  这几个pod 没启动，
检查静态pod配置,在/var/lib/systemd/system/kubelet.service 这个文件里检查配置看到静态配置路径错误
考试环境把正确的/etc/kubernetes/manifest  换成了/etc/kubernetes/DODKSIYF 路径，此路径并不存在，把这个错误的路径换成到存放api/controller-manager/etcd/schedule这几个yaml文件存放的路径，重启Kubelet，排错完成。
再查看node啥的，就OK了

23.TLS问题（一道很长的题目，建议放弃，难度特别大）

24.pv创建

创建指定大小和路径的pv mode ReadWriteOnce

Creae a persistent volume with name app-config of capacity 1Gi and access mode ReadWriteOnce. The type of volume is hostPath and its location is /srv/app-config

https://kubernetes.io/docs/tasks/configure-pod-container/configure-persistent-volume-storage/#create-a-persistentvolume

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv0003
spec
  capacity:
    storage: 1Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: slow
  hostPath:
    path: /data

25、单主集群搭建

要求在ubuntu上使用kubeadm搭建一主一从集群，两个node节点已给出，并且docker apt-get已安装。

注意题目会提示执行kubeadm 命令时要添加参数 --ignore-preflight-errors=xxx

# master和node上:安装kubeam kubelet kubectl

cat <<EOF > /etc/sysctl.d/k8s.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
EOF

sysctl --system

sudo apt-get install -y kubelet kubeadm kubectl
sudo apt-mark hold kubelet kubeadm kubectl

#master初始化
kubeadm init   --ignore-preflight-errors=xxx

#master安装网络
kubectl apply -f https://docs.projectcalico.org/v3.11/manifests/calico.yaml

#node加入集群
kubeadm join  *** --ignore-preflight-errors=xxx

以上命令并不完整，仅仅提供思路，请使用kubeadm搭建集群进行理解。

以上命令均在官方文档中，链接如下：

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/install-kubeadm/

https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/

可在考试过程中进行copy