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
posted @ 2024-08-24 16:57  Jruing  阅读(5)  评论(0)  编辑  收藏  举报