云原生|kubernetes|CKA模拟测试-2022（1---10题）（一）

第一题：

Task weight: 1%

You have access to multiple clusters from your main terminal through kubectl contexts. Write all those context names into /opt/course/1/contexts.

Next write a command to display the current context into /opt/course/1/context_default_kubectl.sh, the command should use kubectl.

Finally write a second command doing the same thing into /opt/course/1/context_default_no_kubectl.sh, but without the use of kubectl.

解析：

题目要求是，你现在访问的是一个多集群，你需要通过kubeclt 命令获取到config的上下文，config的current-context以及不通过kubectl获取到config的上下文以及current-context。

答案：

1，kubectl config get-contexts

2，kubectl config current-context

3，cat $HOME/.kube/config |grep current

第二题：

Task weight: 3%

Use context: kubectl config use-context k8s-c1-H

Create a single Pod of image httpd:2.4.41-alpine in Namespace default. The Pod should be named pod1 and the container should be named pod1-container. This Pod should only be scheduled on a master node, do not add new labels any nodes.

解析：

这道题目要求的是创建一个pod，此pod的名称和镜像和镜像名称都规定了，并且规定是调度到master节点。由此得出需要四个条件才可完成此题。

此题考察的是对pod名称和容器名称的区分以及pod的节点调度。

1，

通过命令快速生成创建pod的模板文件

kubectl run pod1 --image=httpd:2.4.41-alpine  --dry-run=client -oyaml >pod1.yaml

模板文件大概是这个样子 

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - image: httpd:2.4.41-alpine
    name: pod1
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

2，

在模板文件的基础上按题意修改

根据题目来看，我们可以知道pod可以nodeselector，也可以直接nodename，这两种方式都是OK的，但很明显nodename更加的简单

nodeSelector方式：

这个方式是通用的方式，但编写的时候写的东西多一些，比较麻烦，要有亲和

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - image: httpd:2.4.41-alpine
    name: pod1-container                  # change
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  tolerations:                            # add
  - effect: NoSchedule                    # add
    key: node-role.kubernetes.io/master   # add
  nodeSelector:                           # add
    node-role.kubernetes.io/master: ""    # add
status: {}

节点标签如下；

因此，如果是二进制部署的集群，这种方式并不适用，因为没有role标签。

root@k8s-master:~# kubectl get no --show-labels 
NAME         STATUS   ROLES                  AGE     VERSION    LABELS
k8s-master   Ready    control-plane,master   372d    v1.22.10   beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-master,kubernetes.io/os=linux,node-role.kubernetes.io/control-plane=,node-role.kubernetes.io/master=,node.kubernetes.io/exclude-from-external-load-balancers=
k8s-node1    Ready    <none>                 2d17h   v1.22.2    beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node1,kubernetes.io/os=linux
k8s-node2    Ready    <none>                 2d17h   v1.22.2    beta.kubernetes.io/arch=amd64,beta.kubernetes.io/os=linux,kubernetes.io/arch=amd64,kubernetes.io/hostname=k8s-node2,kubernetes.io/os=linux

 

nodename方式：

需要先查询出master节点的名称，这个一定要准确查询

root@k8s-master:~# kubectl get no
NAME         STATUS   ROLES                  AGE     VERSION
k8s-master   Ready    control-plane,master   372d    v1.22.10
k8s-node1    Ready    <none>                 2d17h   v1.22.2
k8s-node2    Ready    <none>                 2d17h   v1.22.2

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: pod1
  name: pod1
spec:
  containers:
  - image: httpd:2.4.41-alpine
    name: pod1-container                  # change
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  nodeName: k8s-master

 

3，

应用模板文件，创建pod

kubectl apply -f pod1.yaml

 

 

第三题：

Task weight: 1%

Use context: kubectl config use-context k8s-c1-H

There are two Pods named o3db-* in Namespace project-c13. C13 management asked you to scale the Pods down to one replica to save resources.

解析：

这个题目比较简单，通过查询pod可以看到这些pod 的名称是有规律的编号，因此，可以推断出是StateFulSet方式部署的。

 

 因此，直接编辑这个sts即可

 

 再次查询pod，结果如上面第一图一样即可了。

第四题：

Task weight: 4%

Use context: kubectl config use-context k8s-c1-H

Do the following in Namespace default. Create a single Pod named ready-if-service-ready of image nginx:1.16.1-alpine. Configure a LivenessProbe which simply runs true. Also configure a ReadinessProbe which does check if the url http://service-am-i-ready:80 is reachable, you can use wget -T2 -O- http://service-am-i-ready:80 for this. Start the Pod and confirm it isn't ready because of the ReadinessProbe.

Create a second Pod named am-i-ready of image nginx:1.16.1-alpine with label id: cross-server-ready. The already existing Service service-am-i-ready should now have that second Pod as endpoint.

Now the first Pod should be in ready state, confirm that.

解析：

本题考查livnessPorbe和readnessProbe，也就是存活探针和运行探针

存活探针使用true，题目中要求的运行探针没有明确规定，它建议使用命令 wget -T2 -O- http://service-am-i-ready:80，但我们使用端口检测也是OK的，

service是环境里已经建立好的，绑定的pod是第二个创建的pod，因此，创建的第二个pod一定要准确：

service的创建文件（已经创建好的，现在只是查看一下，确定是和第二个pod有关而已）：

# Please edit the object below. Lines beginning with a '#' will be ignored,
# and an empty file will abort the edit. If an error occurs while saving this file will be
# reopened with the relevant failures.
#
apiVersion: v1
kind: Service
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"creationTimestamp":null,"labels":{"id":"cross-server-ready"},"name":"service-am-i-ready","namespace":"default"},"spec":{"ports":[{"port":80,"protocol":"TCP","targetPort":80}],"selector":{"id":"cross-server-ready"}},"status":{"loadBalancer":{}}}
  creationTimestamp: "2022-09-29T14:30:58Z"
  labels:
    id: cross-server-ready
  name: service-am-i-ready
  namespace: default
  resourceVersion: "4761"
  uid: 03981930-13d9-4133-8e23-9704c2a24807
spec:
  clusterIP: 10.109.238.68
  clusterIPs:
  - 10.109.238.68
  internalTrafficPolicy: Cluster
  ipFamilies:
  - IPv4
  ipFamilyPolicy: SingleStack
  ports:
  - port: 80
    protocol: TCP
    targetPort: 80
  selector:
    id: cross-server-ready
  sessionAffinity: None
  type: ClusterIP
status:
  loadBalancer: {}

 存活探针的第二种写法：

    readinessProbe:
      exec:
        command:
        - sh
        - -c
        - 'wget -T2 -O- http://service-am-i-ready:80'  

第一个pod： 

apiVersion: v1
kind: Pod
metadata:
  labels:
    run: ready-if-service-ready
  name: ready-if-service-ready
spec:
  containers:
  - image: nginx:1.16.1-alpine
    name: ready-if-service-ready
    ports:
    - containerPort: 80
    readinessProbe:
      tcpSocket:
        port: 80
      initialDelaySeconds: 5
      periodSeconds: 5
    livenessProbe:
      exec:
        command:
        - 'true'
      initialDelaySeconds: 5
      periodSeconds: 5
  dnsPolicy: ClusterFirst
  restartPolicy: Always

apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    id: cross-server-ready
  name: am-i-ready
spec:
  containers:
  - image: nginx:1.16.1-alpine
    name: am-i-ready
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
status: {}

第五题：

Task weight: 1%

Use context: kubectl config use-context k8s-c1-H

There are various Pods in all namespaces. Write a command into /opt/course/5/find_pods.sh which lists all Pods sorted by their AGE (metadata.creationTimestamp).

Write a second command into /opt/course/5/find_pods_uid.sh which lists all Pods sorted by field metadata.uid. Use kubectl sorting for both commands.

解析：

这一题比较的简单，只是要求把查询命令写入文件内即可。

第一个命令是查询所有pod，按创建时间排序的功能，将查询命令写入/opt/course/5/find_pods.sh

第二个命令是查询所有pod，按pod的uid排序，将查询命令写入/opt/course/5/find_pods_uid.sh

cat /opt/course/5/find_pods.sh
kubectl get po --sort-by {.metadata.creationTimestamp} -A

cat /opt/course/5/find_pods_uid.sh
kubectl get po --sort-by {.metadata.uid} -A

 

第六题：

Task weight: 8%

Use context: kubectl config use-context k8s-c1-H

Create a new PersistentVolume named safari-pv. It should have a capacity of 2Gi, accessMode ReadWriteOnce, hostPath /Volumes/Data and no storageClassName defined.

Next create a new PersistentVolumeClaim in Namespace project-tiger named safari-pvc . It should request 2Gi storage, accessMode ReadWriteOnce and should not define a storageClassName. The PVC should bound to the PV correctly.

Finally create a new Deployment safari in Namespace project-tiger which mounts that volume at /tmp/safari-data. The Pods of that Deployment should be of image httpd:2.4.41-alpine.

解析：

这题难度中等，相关代码都得从官网查询，pvc建立后，pvc会自己寻找合适的pv，这里要理解pv设置的是2G，pvc设置的是2G，因此只有这个pv是适合的，也就是通过storage两者建立的联系

pv的创建：

cat safari-pv.yaml 
apiVersion: v1
kind: PersistentVolume
metadata:
  name: safari-pv
spec:
  capacity:
    storage: 2Gi
  volumeMode: Filesystem
  accessModes:
  - ReadWriteOnce
  persistentVolumeReclaimPolicy: Delete
  hostPath:
    path: /Volumes/Data

pvc的创建： 

 cat safari-pvc.yaml 
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: safari-pvc
  namespace: project-tiger
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2Gi

 pv和pvc创建好后就可以看它们的状态了，两个bond才是正确的哦：

k8s@terminal:~$ kubectl get pv,pvc -A
NAME                         CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM                      STORAGECLASS   REASON   AGE
persistentvolume/safari-pv   2Gi        RWO            Delete           Bound    project-tiger/safari-pvc                           4h2m

NAMESPACE       NAME                               STATUS   VOLUME      CAPACITY   ACCESS MODES   STORAGECLASS   AGE
project-tiger   persistentvolumeclaim/safari-pvc   Bound    safari-pv   2Gi        RWO                           3h55m

pvc的使用，这里按题目的要求做即可

 cat safari-dep.yaml 
apiVersion: apps/v1
kind: Deployment
metadata:
  labels:
    app: safari
  name: safari
  namespace: project-tiger
spec:
  replicas: 1
  selector:
    matchLabels:
      app: safari
  strategy: {}
  template:
    metadata:
      labels:
        app: safari
    spec:
      containers:
      - image: httpd:2.4.41-alpine
        name: safari
        resources: {}
        volumeMounts: #这里定义pod中要挂载的路径
        - name: safari
          mountPath: /tmp/safari-data
      volumes:
        - name: safari #和上面的挂载目录一致
          persistentVolumeClaim:
            claimName: safari-pvc #

第七题：

Task weight: 1%

Use context: kubectl config use-context k8s-c1-H

The metrics-server has been installed in the cluster. Your college would like to know the kubectl commands to:

1. show Nodes resource usage
2. show Pods and their containers resource usage

Please write the commands into /opt/course/7/node.sh and /opt/course/7/pod.sh.

解析：

Metrics server 环境是已经安装好的，因此不需要关注，只需要把这两个命令写到对应的文件内即可。

cat /opt/course/7/node.sh
kubectl top nodes -A

cat  /opt/course/7/pod.sh
kubectl top pod --containers=true

 

第八题：

Task weight: 2%

Use context: kubectl config use-context k8s-c1-H

Ssh into the master node with ssh cluster1-master1. Check how the master components kubelet, kube-apiserver, kube-scheduler, kube-controller-manager and etcd are started/installed on the master node. Also find out the name of the DNS application and how it's started/installed on the master node.

Write your findings into file /opt/course/8/master-components.txt. The file should be structured like:

# /opt/course/8/master-components.txt
kubelet: [TYPE]
kube-apiserver: [TYPE]
kube-scheduler: [TYPE]
kube-controller-manager: [TYPE]
etcd: [TYPE]
dns: [TYPE] [NAME]

Choices of [TYPE] are: not-installed, process, static-pod, pod

解析：

先登录cluster1-master1，也就是ssh cluster1-master1，然后使用命令kubectl get po -A 查看pod的状态，确认pod是如何部署的即可，题目内已经给了选项了，按顺序填写进文件内即可，答案在下面

答案：

cat /opt/course/8/master-components.txt
# /opt/course/8/master-components.txt
kubelet:process
kube-apiserver: static-pod
kube-scheduler: static-pod
kube-controller-manager:static-pod
etcd: static-pod
dns: pod coredns

第九题：

Task weight: 5%

Use context: kubectl config use-context k8s-c2-AC

Ssh into the master node with ssh cluster2-master1. Temporarily stop the kube-scheduler, this means in a way that you can start it again afterwards.

Create a single Pod named manual-schedule of image httpd:2.4-alpine, confirm its created but not scheduled on any node.

Now you're the scheduler and have all its power, manually schedule that Pod on node cluster2-master1. Make sure it's running.

Start the kube-scheduler again and confirm its running correctly by creating a second Pod named manual-schedule2 of image httpd:2.4-alpine and check if it's running on cluster2-worker1.

解析：

此题考察了静态pod的重启，也就是最后一步，需要来回移动一次/etc/kubernetes/manifests/kube-scheduler.yaml这个文件，同时考察节点选择策略，

cat manual-schedule.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: manual-schedule
  name: manual-schedule
spec:
  containers:
  - image: httpd:2.4-alpine
    name: manual-schedule
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  nodeName: cluster2-master1
status: {}

 

cat manual-schedule2.yaml 
apiVersion: v1
kind: Pod
metadata:
  creationTimestamp: null
  labels:
    run: manual-schedule2
  name: manual-schedule2
spec:
  containers:
  - image: httpd:2.4-alpine
    name: manual-schedule2
    resources: {}
  dnsPolicy: ClusterFirst
  restartPolicy: Always
  nodeName: cluster2-worker1
status: {}

第十题：

Task weight: 6%

Use context: kubectl config use-context k8s-c1-H

Create a new ServiceAccount processor in Namespace project-hamster. Create a Role and RoleBinding, both named processor as well. These should allow the new SA to only create Secrets and ConfigMaps in that Namespace.

解析：

这一题是RBAC

建立role

kubectl -n project-hamster create role processor --verb=create --resource=secret --resource=configmap

apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: processor
  namespace: project-hamster
rules:
- apiGroups:
  - ""
  resources:
  - secrets
  - configmaps
  verbs:
  - create

 建立rolebinding

k -n project-hamster create rolebinding processor
–role processor
–serviceaccount project-hamster:processor

apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: processor
  namespace: project-hamster
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: processor
subjects:
- kind: ServiceAccount
  name: processor
  namespace: project-hamster