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
-
关闭防火墙
systemctl disable firewalld --now -
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 -
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 servercurl -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
-
k8s-master节点添加镜像加速配置文件/etc/rancher/k3s/registries.yamlmirrors: 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" -
分发到
k8s-worker1和k8s-worker2scp /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 -
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 -
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 execkubectl 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。
-
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[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 namespacespec- 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
本文来自博客园，作者：Jruing，转载请注明原文链接：https://www.cnblogs.com/jruing/p/18377941
