kubernetes学习笔记

基础环境#

系统镜像版本

  • Centos 7.6 最小化

最低运行环境基本要求

  • 内存及CPU：512MB / CPU 1核

K3s版本

  • v1.30.0+k3s1

集群规划:

注意：需要对每台主机设置hostname,使用 hostnamectl set-hostname 主机名

  • K8s-master 192.168.200.129 1C/1G
  • K8s-worker1 192.168.200.130 2C/2G
  • K8s-worker2 192.168.200.131 2C/2G

准备工作#

  1. 关闭防火墙

    systemctl disable firewalld --now

  2. 设置Selinux(需要接入互联网)

    yum install -y container-selinux selinux-policy-base yum install -y https://rpm.rancher.io/k3s/latest/common/centos/7/noarch/k3s-selinux-0.2-1.el7_8.noarch.rpm

  3. 免密登录

    		ssh-keygen -t rsa
    		ssh-copy-id -i /root/.ssh/id_rsa.pub 192.168.200.130
    		ssh-copy-id -i /root/.ssh/id_rsa.pub 192.168.200.131

安装K3s集群#

K3s集群分为K3s server（控制平面） 及 k3s agent （工作节点）

  • 在k8s-master 节点安装k3s server

    		curl -sfL https://rancher-mirror.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -

卸载K3s集群#

k3s-uninstall.sh

验证安装#

  • 查看节点状态 kubectl get node

    		[root@localhost ~]# kubectl get node
    		NAME         STATUS   ROLES                  AGE   VERSION
    		k8s-master   Ready    control-plane,master   16s   v1.30.4+k3s1

  • 查看token cat /var/lib/rancher/k3s/server/node-token

    这个token用于K8s-worker1和K8s-worker2这两个节点加入集群

    		[root@localhost ~]# cat /var/lib/rancher/k3s/server/node-token
    		K103b59c9e5e4a8904ad2f4ba0dc2fc17079af59e8cd3f8f7c51f5a42d62a373eb0::server:e2b46796a195fe2a86de36c54855802e

节点加入集群#

分别在k8s-worker1 和 k8s-worker2 两台主机分别执行以下命令

curl -sfL https://rancher-mirror.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn K3S_URL=https://192.168.200.129:6443 K3S_TOKEN=K103b59c9e5e4a8904ad2f4ba0dc2fc17079af59e8cd3f8f7c51f5a42d62a373eb0::server:e2b46796a195fe2a86de36c54855802e sh -

在k8s-master节点执行kubectl get node，可以看到k8s-worker1 和 k8s-worker2 已经加入集群

[root@k8s-master ~]# kubectl get node
NAME          STATUS   ROLES                  AGE     VERSION
k8s-master    Ready    control-plane,master   57m     v1.30.4+k3s1
k8s-worker1   Ready    <none>                 4m46s   v1.30.4+k3s1
k8s-worker2   Ready    <none>                 3m33s   v1.30.4+k3s1

镜像加速#

  1. k8s-master节点添加镜像加速配置文件 /etc/rancher/k3s/registries.yaml

    		mirrors:
    		  docker.io:
    		    endpoint:
    		      - "https://hub.uuuadc.top"
    		      - "https://docker.anyhub.us.kg"
    		      - "https://dockerhub.jobcher.com"
    		      - "https://dockerhub.icu"
    		      - "https://docker.ckyl.me"
    		      - "https://docker.awsl9527.cn"

  2. 分发到k8s-worker1 和 k8s-worker2

    		scp /etc/rancher/k3s/registries.yaml root@192.168.200.130:/etc/rancher/k3s/registries.yaml
    		scp /etc/rancher/k3s/registries.yaml root@192.168.200.131:/etc/rancher/k3s/registries.yaml

  3. 重启k3s-server及k3s-agent

    		# 在k8s-master节点执行
    		systemctl restart k3s
    		# 在k8s-worker1和k8s-worker2节点执行
    		systemctl restart k3s-agent

  4. 验证

    		# 拉取mysql镜像
    		[root@k8s-master ~]# crictl pull mysql:5.7-debian
    		Image is up to date for sha256:6dca1336186922918678a49811059c4f6bfa1759d853a4e7cde904879d2e9b83
    		# 查看镜像列表
    		[root@k8s-master ~]# crictl  images
    		IMAGE                     TAG                 IMAGE ID            SIZE
    		docker.io/library/mysql   5.7-debian          6dca133618692       163MB

Pod#

  • 创建Pod资源 kubectl run

    		# 创建一个名称为 mynginx，镜像为 nginx 的Pod
    		[root@k8s-master ~]# kubectl run mynginx --image=nginx
    		pod/mynginx created

  • 查看Pod kubectl get pod

    		[root@k8s-master ~]# kubectl get pod
    		NAME      READY   STATUS    RESTARTS   AGE
    		mynginx   1/1     Running   0          11m
    		# 显示pod的IP和运行节点信息
    		[root@k8s-master ~]# kubectl get pod -owide
    		NAME      READY   STATUS    RESTARTS   AGE     IP          NODE          NOMINATED NODE   READINESS GATES
    		mynginx   1/1     Running   0          4m40s   10.42.2.3   k8s-worker2   <none>           <none>

  • 查看Pod运行日志 kubectl logs

    		[root@k8s-master ~]# kubectl logs mynginx
    		/docker-entrypoint.sh: /docker-entrypoint.d/ is not empty, will attempt to perform configuration
    		/docker-entrypoint.sh: Looking for shell scripts in /docker-entrypoint.d/
    		/docker-entrypoint.sh: Launching /docker-entrypoint.d/10-listen-on-ipv6-by-default.sh
    		10-listen-on-ipv6-by-default.sh: info: Getting the checksum of /etc/nginx/conf.d/default.conf
    		10-listen-on-ipv6-by-default.sh: info: Enabled listen on IPv6 in /etc/nginx/conf.d/default.conf
    		/docker-entrypoint.sh: Sourcing /docker-entrypoint.d/15-local-resolvers.envsh
    		/docker-entrypoint.sh: Launching /docker-entrypoint.d/20-envsubst-on-templates.sh
    		/docker-entrypoint.sh: Launching /docker-entrypoint.d/30-tune-worker-processes.sh
    		/docker-entrypoint.sh: Configuration complete; ready for start up
    		2024/08/24 05:50:48 [notice] 1#1: using the "epoll" event method
    		2024/08/24 05:50:48 [notice] 1#1: nginx/1.27.1
    		2024/08/24 05:50:48 [notice] 1#1: built by gcc 12.2.0 (Debian 12.2.0-14) 
    		2024/08/24 05:50:48 [notice] 1#1: OS: Linux 3.10.0-1160.el7.x86_64
    		2024/08/24 05:50:48 [notice] 1#1: getrlimit(RLIMIT_NOFILE): 1048576:1048576
    		2024/08/24 05:50:48 [notice] 1#1: start worker processes
    		2024/08/24 05:50:48 [notice] 1#1: start worker process 29
    		2024/08/24 05:50:48 [notice] 1#1: start worker process 30
    		2024/08/24 05:50:48 [notice] 1#1: start worker process 31
    		2024/08/24 05:50:48 [notice] 1#1: start worker process 32
    		10.42.0.0 - - [24/Aug/2024:05:51:59 +0000] "GET / HTTP/1.1" 200 615 "-" "curl/7.29.0" "-"

  • 查看Pod详细信息

    		[root@k8s-master ~]# kubectl describe pod mynginx
    		Name:             mynginx
    		Namespace:        default
    		Priority:         0
    		Service Account:  default
    		Node:             k8s-worker2/192.168.200.131
    		Start Time:       Sat, 24 Aug 2024 13:46:18 +0800
    		Labels:           run=mynginx
    		Annotations:      <none>
    		Status:           Pending
    		IP:               
    		IPs:              <none>
    		Containers:
    		  mynginx:
    		    Container ID:   
    		    Image:          nginx
    		    Image ID:       
    		    Port:           <none>
    		    Host Port:      <none>
    		    State:          Waiting
    		      Reason:       ContainerCreating
    		    Ready:          False
    		    Restart Count:  0
    		    Environment:    <none>
    		    Mounts:
    		      /var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-w4xqw (ro)
    		Conditions:
    		  Type                        Status
    		  PodReadyToStartContainers   False 
    		  Initialized                 True 
    		  Ready                       False 
    		  ContainersReady             False 
    		  PodScheduled                True 
    		Volumes:
    		  kube-api-access-w4xqw:
    		    Type:                    Projected (a volume that contains injected data from multiple sources)
    		    TokenExpirationSeconds:  3607
    		    ConfigMapName:           kube-root-ca.crt
    		    ConfigMapOptional:       <nil>
    		    DownwardAPI:             true
    		QoS Class:                   BestEffort
    		Node-Selectors:              <none>
    		Tolerations:                 node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
    		                             node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
    		Events:
    		  Type    Reason     Age   From               Message
    		  ----    ------     ----  ----               -------
    		  Normal  Scheduled  13s   default-scheduler  Successfully assigned default/mynginx to k8s-worker2

  • 在容器中执行命令 kubectl exec

    		kubectl exec mynginx -it -- /bin/bash

  • 删除Pod kubectl delete

    		# 删除Pod
    		kubectl delete pod mynginx
    		# 强制删除
    		kubectl delete pod mynginx --force

Deployment与ReplicaSet#

  • Deployment使Pod具有自愈的能力，当我们删除Deployment中的一个或多个pod后，他会自动创建Pod直到与副本数量一致
  • Deployment使Pod具有滚动更新及版本回退的能力

  • 创建Deployment kubectl create deployment

    		# 创建一个deployment资源，名称为nginx-deployment，镜像为nginx:1.22 ，副本数量为3
    		[root@k8s-master ~]# kubectl create deployment nginx-deployment --image=nginx:1.22 --replicas=3
    		deployment.apps/nginx-deployment created

  • 查看Deployment

    		[root@k8s-master ~]# kubectl get deploy 
    		NAME               READY   UP-TO-DATE   AVAILABLE   AGE
    		nginx-deployment   3/3     3            3           5m9s

  • 查看Pod

    		[root@k8s-master ~]# kubectl get pod
    		NAME                                READY   STATUS    RESTARTS   AGE
    		mynginx                             1/1     Running   0          28m
    		nginx-deployment-645dcd4477-87twt   1/1     Running   0          5m58s
    		nginx-deployment-645dcd4477-9xb9p   1/1     Running   0          5m58s
    		nginx-deployment-645dcd4477-j9xt8   1/1     Running   0          5m58s

  • 查看Deployment的副本数量 kubectl get replicaSet

    		[root@k8s-master ~]# kubectl get replicaSet
    		NAME                          DESIRED   CURRENT   READY   AGE
    		nginx-deployment-645dcd4477   3         3         3       6m36s

  • 手动扩缩容 kubectl scale deploy 资源名称 --replicas=数量

    		# 将deployment/nginx-deployment的副本集扩充到5个
    		[root@k8s-master ~]# kubectl scale deployment/nginx-deployment --replicas=5
    		deployment.apps/nginx-deployment scaled
    		# 查看扩缩后的Pod
    		[root@k8s-master ~]# kubectl get pod
    		NAME                                READY   STATUS    RESTARTS   AGE
    		mynginx                             1/1     Running   0          36m
    		nginx-deployment-645dcd4477-87twt   1/1     Running   0          13m
    		nginx-deployment-645dcd4477-9xb9p   1/1     Running   0          13m
    		nginx-deployment-645dcd4477-df828   1/1     Running   0          19s
    		nginx-deployment-645dcd4477-j9xt8   1/1     Running   0          13m
    		nginx-deployment-645dcd4477-t4cw5   1/1     Running   0          19s

  • 自动扩缩容 kubectl autoscale 资源名称 --min=最小pod数 --max=最大pod数 扩缩容条件

    扩缩容条件参考：https://github.com/kubernetes-sigs/metrics-server#readme

    		#自动缩放，设置deployment/nginx-deployment为自动扩缩容，最小数量为3个pod，最大为10个pod，扩缩容的条件是所有pod的平均cpu使用率不超过75%
    		[root@k8s-master ~]# kubectl autoscale deployment/nginx-deployment --min=3 --max=10 --cpu-percent=75 
    		horizontalpodautoscaler.autoscaling/nginx-deployment autoscaled

  • 滚动更新

    注意：在滚动更新的过程中会出现新旧服务共存在的状态

    		# 设定deployment/nginx-deployment的镜像为nginx:1.23版本
    		[root@k8s-master ~]# kubectl set image deployment/nginx-deployment nginx=nginx:1.23
    		deployment.apps/nginx-deployment image updated
    		#滚动更新状态
    		kubectl rollout status deployment/nginx-deployment
    		#查看过程
    		kubectl get rs --watch

  • 查看历史版本 kubectl rollout history

    		[root@k8s-master ~]# kubectl rollout history deployment/nginx-deployment
    		deployment.apps/nginx-deployment 
    		REVISION  CHANGE-CAUSE
    		1         <none>
    		2         <none>

  • 查看指定版本 kubectl rollout history deployment资源名称 --revision=版本号

    		[root@k8s-master ~]# kubectl rollout history deployment/nginx-deployment --revision=2
    		deployment.apps/nginx-deployment with revision #2
    		Pod Template:
    		  Labels:	app=nginx-deployment
    			pod-template-hash=5cf4667cdb
    		  Containers:
    		   nginx:
    		    Image:	nginx:1.23
    		    Port:	<none>
    		    Host Port:	<none>
    		    Environment:	<none>
    		    Mounts:	<none>
    		  Volumes:	<none>
    		  Node-Selectors:	<none>
    		  Tolerations:	<none>

  • 回滚到历史版本 kubectl rollout undo deployment资源名称 --to-revision=版本号

    		[root@k8s-master ~]# kubectl rollout undo deployment/nginx-deployment --to-revision=1
    		deployment.apps/nginx-deployment rolled back

Service#

Service会将将运行在一组Pod上的应用公开为网络服务，并为该组Pod提供相同的DNS名称，进行负载均衡。Kubernetes 为 Pod 提供分配了IP 地址，但IP地址可能会发生变化。Service会使集群内的容器可以通过service名称访问服务，而不需要担心Pod的IP发生变化。

image.png

  • 创建Service资源

    ServiceType 取值

    • ClusterIP：将服务公开在集群内部。kubernetes会给服务分配一个集群内部的 IP，集群内的所有主机都可以通过这个Cluster-IP访问服务。集群内部的Pod可以通过service名称访问服务。
    • NodePort：通过每个节点的主机IP 和静态端口（NodePort）暴露服务。 集群的外部主机可以使用节点IP和NodePort访问服务。
    • ExternalName：将集群外部的网络引入集群内部。
    • LoadBalancer：使用云提供商的负载均衡器向外部暴露服务。
    		# 创建一个名称为nginx-service的Service，使用的资源为deployment/nginx-deployment，集群内部暴露的端口为8080，目标端口为80,这个服务只能在集群内部访问，无法在外部访问
    		[root@k8s-master ~]#  kubectl expose deployment/nginx-deployment --name nginx-service --port=8080 --target-port=80
    		service/nginx-service exposed
    		 
    		# 创建一个名称为nginx-service的Service，使用的资源为deployment/nginx-deployment，对外暴露的端口为8081，目标端口为80
    		[root@k8s-master ~]# kubectl expose deployment/nginx-deployment --name=nginx-outside --type=NodePort --port=8081 --target-port=80
    		service/nginx-outside exposed

  • 查看Service kubectl get service

    		# nginx-outside暴露了两个端口，8081是集群内部访问的端口，31606是外部访问的端口（http://192.168.200.129:31606）
    		[root@k8s-master ~]# kubectl get service
    		NAME            TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)    AGE
    		kubernetes      ClusterIP   10.43.0.1      <none>        443/TCP    178m
    		nginx-outside   NodePort    10.43.151.51   <none>        8081:31606/TCP   7s
    		nginx-service   ClusterIP   10.43.21.154   <none>        8080/TCP   2m41s
    		 
    		# 通过集群分配的ip+端口访问服务
    		[root@k8s-master ~]# curl 10.43.21.154:8080
    		<!DOCTYPE html>
    		<html>
    		<head>
    		<title>Welcome to nginx!</title>
    		<style>
    		html { color-scheme: light dark; }
    		body { width: 35em; margin: 0 auto;
    		font-family: Tahoma, Verdana, Arial, sans-serif; }
    		</style>
    		</head>
    		<body>
    		<h1>Welcome to nginx!</h1>
    		<p>If you see this page, the nginx web server is successfully installed and
    		working. Further configuration is required.</p>
    		 
    		<p>For online documentation and support please refer to
    		<a href="http://nginx.org/">nginx.org</a>.<br/>
    		Commercial support is available at
    		<a href="http://nginx.com/">nginx.com</a>.</p>
    		 
    		<p><em>Thank you for using nginx.</em></p>
    		</body>
    		</html>
    		 
    		# 通过--rm参数创建一个一次性的pod(退出pod后会自动销毁)
    		[root@k8s-master ~]# kubectl run test -it --image=nginx:1.22 --rm -- bash
    		If you don't see a command prompt, try pressing enter.
    		 
    		# 通过服务名称+端口进行访问
    		root@test:/# curl nginx-service:8080
    		<!DOCTYPE html>
    		<html>
    		<head>
    		<title>Welcome to nginx!</title>
    		<style>
    		html { color-scheme: light dark; }
    		body { width: 35em; margin: 0 auto;
    		font-family: Tahoma, Verdana, Arial, sans-serif; }
    		</style>
    		</head>
    		<body>
    		<h1>Welcome to nginx!</h1>
    		<p>If you see this page, the nginx web server is successfully installed and
    		working. Further configuration is required.</p>
    		 
    		<p>For online documentation and support please refer to
    		<a href="http://nginx.org/">nginx.org</a>.<br/>
    		Commercial support is available at
    		<a href="http://nginx.com/">nginx.com</a>.</p>
    		 
    		<p><em>Thank you for using nginx.</em></p>
    		</body>
    		</html>

  • 查看service详细信息 kubectl describe service 服务名称

    		[root@k8s-master ~]# kubectl describe service nginx-service
    		Name:              nginx-service
    		Namespace:         default
    		Labels:            app=nginx-deployment
    		Annotations:       <none>
    		Selector:          app=nginx-deployment
    		Type:              ClusterIP
    		IP Family Policy:  SingleStack
    		IP Families:       IPv4
    		IP:                10.43.21.154
    		IPs:               10.43.21.154
    		Port:              <unset>  8080/TCP
    		TargetPort:        80/TCP
    		Endpoints:         10.42.0.11:80,10.42.1.8:80,10.42.1.9:80 + 2 more... # 负载均衡端点
    		Session Affinity:  None
    		Events:            <none>

NameSpace#

  • 查看命名空间 kubectl get namespace

    • default 默认的命名空间，不可删除，未指定命名空间的对象都会被分配到default中。
    • kube-system Kubernetes 系统对象(控制平面和Node组件)所使用的命名空间。
    • kube-public 自动创建的公共命名空间，所有用户（包括未经过身份验证的用户）都可以读取它。通常我们约定，将整个集群中公用的可见和可读的资源放在这个空间中。
    • kube-node-lease 租约（Lease）对象使用的命名空间。每个节点都有一个关联的 lease 对象，lease 是一种轻量级资源。lease对象通过发送心跳，检测集群中的每个节点是否发生故障。
    		[root@k8s-master ~]# kubectl get namespace
    		NAME              STATUS   AGE
    		default           Active   3h19m
    		kube-node-lease   Active   3h19m
    		kube-public       Active   3h19m
    		kube-system       Active   3h19m

  • 创建命名空间 kubectl create namespace dev

    在创建Pod的时候可以使用 -n 参数指定命名空间

    		[root@k8s-master ~]# kubectl create namespace dev
    		namespace/dev created

  • 删除命名空间

    删除命名空间时会同步删除该命名空间下的资源

    		[root@k8s-master ~]# kubectl delete namespace dev
    		namespace "dev" deleted

  • 将dev设为当前命名空间，后续所有操作都在此命名空间下执行。

    		kubectl config set-context $(kubectl config current-context) --namespace=dev

通过声明式对象配置#

  • 配置对象

    在创建的 Kubernetes 对象所对应的 yaml文件中，需要配置的字段如下：

    • apiVersion - Kubernetes API 的版本
    • kind - 对象类别，例如Pod、Deployment、Service、ReplicaSet等
    • metadata - 描述对象的元数据，包括一个 name 字符串、UID 和可选的 namespace
    • spec - 对象的配置

  • 栗子

    这个配置文件中的Pod资源通常不需要单独定义，因为Pod将由Deployment自动创建和管理。Pod资源在这里是为了演示配置文件的结构，但在实际使用中，Deployment足以管理Pod的生命周期。

    		apiVersion: v1 # api版本信息
    		kind: Pod # 资源类型
    		metadata:
    		  name: nginx
    		  labels:
    		    app.kubernetes.io/name: proxy # 定义一个key为name，value为proxy的标签
    		spec:
    		  containers: # 下面为运行的容器列表
    		  - name: nginx # 容器名称
    		    image: nginx:1.22 # 镜像名称及版本号
    		    ports:
    		      - containerPort: 80 # 容器内部监听的端口
    		---
    		apiVersion: apps/v1
    		kind: Deployment
    		metadata:
    		  name: nginx-deployment-demo # deployment资源名称
    		  labels:
    		    app: nginx  # 定义一个key为app，value为nginx的标签
    		spec:
    		  replicas: 3 # 指定副本数量为3个
    		  selector:
    		    matchLabels:
    		      app: nginx # 匹配标签key为app，value为nginx的所有资源
    		  template:
    		    metadata:
    		      labels:
    		        app: nginx # 定义一个key为app，value为nginx的标签
    		    spec:
    		      containers: # 下面为运行的容器列表
    		      - name: nginx # 容器名称
    		        image: nginx:1.22 # 镜像名称及版本号
    		        ports:
    		        - containerPort: 80 # 容器内部监听的端口
    		---
    		apiVersion: v1
    		kind: Service # 资源类型
    		metadata:
    		  name: nginx-service-demo # 定义服务名称
    		spec:
    		  selector:
    		    app: nginx # 匹配标签key为app，value为nginx的所有资源
    		  ports:
    		    - name: nginx-out-side 
    		      port: 80 # 集群内部暴露的端口
    		      nodePort: 31009 # 对外暴露的端口
    		      targetPort: 80 # 目标端口
    		  type: NodePort # 指定服务类型

  • 通过配置文件创建Pod

    		kubectl apply -f my-nginx.yaml

  • 通过配置文件删除Pod

    		kubectl delete -f my-nginx.yaml

作者：jruing

出处：https://www.cnblogs.com/jruing/p/18377941

版权：本作品采用「署名-非商业性使用-相同方式共享 4.0 国际」许可协议进行许可。

posted @   Jruing  阅读(13)  评论(0)  编辑  收藏  举报
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