4 使用Service暴露应用服务
4.1 概念
Kubernetes 中的服务(Service)是一种抽象概念,它定义了 Pod 的逻辑集和访问 Pod 的协议。
每个 Pod 都有唯一的 IP 地址,但是类似于内网IP,需要 Service进行对外暴露 。
Service 也可以用在 ServiceSpec 标记type有以下几种:
- ClusterIP(默认) :在集群的内部 IP 上公开 Service 。这种类型使得 Service 只能从集群内访问。
- NodePort:使用 NAT 在集群中每个选定 Node 的相同端口上公开 Service 。是 ClusterIP 的超集。
- LoadBalancer:在当前集群中创建一个外部负载均衡器,并为 Service 分配一个固定的外部IP。是 NodePort 的超集。
- ExternalName :通过返回带有该名称的 CNAME 记录,使用任意名称公开 Service。
4.2 演示
基本步骤:
- 根据Deployment,指定type和port生成Service
- 查看Service生成情况
- 进行服务测试
root@ymx-ubuntu:~# kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-65d5b99f84-9kll4 1/1 Running 0 18m root@ymx-ubuntu:~# kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 31m root@ymx-ubuntu:~# kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080 service/kubernetes-bootcamp exposed root@ymx-ubuntu:~# kubectl get services NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 31m kubernetes-bootcamp NodePort 10.104.163.225 <none> 8080:31209/TCP 1s root@ymx-ubuntu:~# kubectl describe services/kubernetes-bootcamp Name: kubernetes-bootcamp ...... Type: NodePort IP Family Policy: SingleStack IP Families: IPv4 IP: 10.104.163.225 IPs: 10.104.163.225 Port: <unset> 8080/TCP TargetPort: 8080/TCP NodePort: <unset> 31209/TCP Endpoints: 172.17.0.4:8080 ...... root@ymx-ubuntu:~# export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-template='{{(index .spec.ports 0).nodePort}}') root@ymx-ubuntu:~# echo NODE_PORT=$NODE_PORT NODE_PORT=31209 root@ymx-ubuntu:~# curl $(minikube ip):$NODE_PORT Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-65d5b99f84-9kll4 | v=1 复制代码
5 扩展和缩放应用
5.1 概念
扩展 Deployment 将创建新的 Pods,并将资源调度请求分配到有可用资源的节点上,收缩 会将 Pods 数量减少至所需的状态。扩缩是通过改变 Deployment 中的副本数量来实现的。 (Kubernetes 还支持 Pods 的自动缩放)
5.2 演示
基本步骤较为简单,最常用的两个命令:
- kubectl get rs:查看目前所有的replica set,显示了所有的pod的副本数,以及他们的可用数量以及状态等信息
- kubectl scale:扩容或缩容
Deployment
、ReplicaSet
、Replication Controller
或Job
中Pod
数量
root@ymx-ubuntu:~# kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 1/1 1 1 34m root@ymx-ubuntu:~# kubectl get rs NAME DESIRED CURRENT READY AGE kubernetes-bootcamp-65d5b99f84 1 1 1 35m 复制代码
扩展:
root@ymx-ubuntu:~# kubectl scale deployments/kubernetes-bootcamp --replicas=4 deployment.apps/kubernetes-bootcamp scaled root@ymx-ubuntu:~# kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 4/4 4 4 36m root@ymx-ubuntu:~# kubectl get rs NAME DESIRED CURRENT READY AGE kubernetes-bootcamp-65d5b99f84 4 4 4 36m root@ymx-ubuntu:~# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kubernetes-bootcamp-65d5b99f84-8knvl 1/1 Running 0 29s 172.17.0.6 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-9kll4 1/1 Running 0 36m 172.17.0.4 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-9vd7m 1/1 Running 0 29s 172.17.0.3 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-gp6jv 1/1 Running 0 29s 172.17.0.5 minikube <none> <none> root@ymx-ubuntu:~# kubectl describe deployments/kubernetes-bootcamp Name: kubernetes-bootcamp Namespace: default CreationTimestamp: Fri, 13 May 2022 19:42:01 +0800 Labels: app=kubernetes-bootcamp Annotations: deployment.kubernetes.io/revision: 1 Selector: app=kubernetes-bootcamp Replicas: 4 desired | 4 updated | 4 total | 4 available | 0 unavailable StrategyType: RollingUpdate ...... root@ymx-ubuntu:~# kubectl describe services/kubernetes-bootcamp Name: kubernetes-bootcamp ...... NodePort: <unset> 31209/TCP Endpoints: 172.17.0.3:8080,172.17.0.4:8080,172.17.0.5:8080 + 1 more... ...... root@ymx-ubuntu:~# export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-template='{{(index .spec.ports 0).nodePort}}') root@ymx-ubuntu:~# echo NODE_PORT=$NODE_PORT NODE_PORT=31209 root@ymx-ubuntu:~# root@ymx-ubuntu:~# curl $(minikube ip):$NODE_PORT Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-65d5b99f84-9vd7m | v=1 复制代码
收缩:
root@ymx-ubuntu:~# kubectl scale deployments/kubernetes-bootcamp --replicas=2 deployment.apps/kubernetes-bootcamp scaled root@ymx-ubuntu:~# kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 2/2 2 2 14h root@ymx-ubuntu:~# kubectl get pods -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES kubernetes-bootcamp-65d5b99f84-8knvl 1/1 Terminating 0 13h 172.17.0.6 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-9kll4 1/1 Running 0 14h 172.17.0.4 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-9vd7m 1/1 Terminating 0 13h 172.17.0.3 minikube <none> <none> kubernetes-bootcamp-65d5b99f84-gp6jv 1/1 Running 0 13h 172.17.0.5 minikube <none> <none> 复制代码
6 更新和滚动更新应用
6.1 概念
用户希望应用程序始终可用,而开发人员则需要每天多次部署它们的新版本。在 Kubernetes 中,这些是通过滚动更新(Rolling Updates)完成的。 滚动更新 允许通过使用新的实例逐步更新 Pod 实例,零停机进行 Deployment 更新。新的 Pod 将在具有可用资源的节点上进行调度。
在 Kubernetes 中,更新是经过版本控制的,任何 Deployment 更新都可以恢复到以前的(稳定)版本。
如果公开了 Deployment,服务将在更新期间仅对可用的 pod 进行负载均衡。
滚动更新允许以下操作:
- 将应用程序从一个环境提升到另一个环境(通过容器镜像更新)
- 回滚到以前的版本
- 持续集成和持续交付应用程序,无需停机
如果 Deployment 是公开的,则服务将仅在更新期间对可用的 pod 进行负载均衡。
6.2 演示
基本步骤:
- 获取将要更新的镜像
- 使用新镜像进行对Deployment的替换(回滚)
- 查看更新详情
root@ymx-ubuntu:~# kubectl get deployments NAME READY UP-TO-DATE AVAILABLE AGE kubernetes-bootcamp 2/2 2 2 14h root@ymx-ubuntu:~# kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-65d5b99f84-9kll4 1/1 Running 0 14h kubernetes-bootcamp-65d5b99f84-gp6jv 1/1 Running 0 13h root@ymx-ubuntu:~# kubectl describe pods Name: kubernetes-bootcamp-65d5b99f84-9kll4 Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Fri, 13 May 2022 19:42:01 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=65d5b99f84 Annotations: <none> Status: Running IP: 172.17.0.4 IPs: IP: 172.17.0.4 Controlled By: ReplicaSet/kubernetes-bootcamp-65d5b99f84 ...... Name: kubernetes-bootcamp-65d5b99f84-gp6jv Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Fri, 13 May 2022 20:17:57 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=65d5b99f84 Annotations: <none> Status: Running IP: 172.17.0.5 IPs: IP: 172.17.0.5 Controlled By: ReplicaSet/kubernetes-bootcamp-65d5b99f84 ...... root@ymx-ubuntu:~# docker images REPOSITORY TAG IMAGE ID CREATED SIZE gcr.io/k8s-minikube/kicbase v0.0.30 1312ccd2422d 3 months ago 1.14GB gcr.io/google-samples/kubernetes-bootcamp v1 8fafd8af70e9 5 years ago 211MB root@ymx-ubuntu:~# docker pull jocatalin/kubernetes-bootcamp:v2 ...... docker.io/jocatalin/kubernetes-bootcamp:v2 root@ymx-ubuntu:~# docker images REPOSITORY TAG IMAGE ID CREATED SIZE gcr.io/k8s-minikube/kicbase v0.0.30 1312ccd2422d 3 months ago 1.14GB jocatalin/kubernetes-bootcamp v2 b6556396ebd4 5 years ago 211MB gcr.io/google-samples/kubernetes-bootcamp v1 8fafd8af70e9 5 years ago 211MB root@ymx-ubuntu:~# kubectl set image deployments/kubernetes-bootcamp kubernetes-bootcamp=jocatalin/kubernetes-bootcamp:v2 deployment.apps/kubernetes-bootcamp image updated root@ymx-ubuntu:~# kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-65d5b99f84-9kll4 1/1 Terminating 0 14h kubernetes-bootcamp-65d5b99f84-gp6jv 1/1 Terminating 0 14h kubernetes-bootcamp-684bd555bb-hfkk7 1/1 Running 0 24s kubernetes-bootcamp-684bd555bb-sxsg9 1/1 Running 0 10s root@ymx-ubuntu:~# kubectl describe services/kubernetes-bootcamp Name: kubernetes-bootcamp Namespace: default Labels: app=kubernetes-bootcamp Annotations: <none> Selector: app=kubernetes-bootcamp Type: NodePort IP Family Policy: SingleStack IP Families: IPv4 IP: 10.104.163.225 IPs: 10.104.163.225 Port: <unset> 8080/TCP TargetPort: 8080/TCP NodePort: <unset> 31209/TCP Endpoints: 172.17.0.3:8080,172.17.0.6:8080 Session Affinity: None ...... root@ymx-ubuntu:~# export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-template='{{(index .spec.ports 0).nodePort}}') root@ymx-ubuntu:~# echo NODE_PORT=$NODE_PORT NODE_PORT=31209 root@ymx-ubuntu:~# curl $(minikube ip):$NODE_PORT Hello Kubernetes bootcamp! | Running on: kubernetes-bootcamp-684bd555bb-sxsg9 | v=2 root@ymx-ubuntu:~# kubectl rollout status deployments/kubernetes-bootcamp deployment "kubernetes-bootcamp" successfully rolled out root@ymx-ubuntu:~# kubectl describe pods Name: kubernetes-bootcamp-684bd555bb-hfkk7 Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Sat, 14 May 2022 10:18:39 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=684bd555bb Annotations: <none> Status: Running IP: 172.17.0.3 IPs: IP: 172.17.0.3 Controlled By: ReplicaSet/kubernetes-bootcamp-684bd555bb ...... Name: kubernetes-bootcamp-684bd555bb-sxsg9 Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Sat, 14 May 2022 10:18:53 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=684bd555bb Annotations: <none> Status: Running IP: 172.17.0.6 IPs: IP: 172.17.0.6 Controlled By: ReplicaSet/kubernetes-bootcamp-684bd555bb ...... 复制代码
回滚:
root@ymx-ubuntu:~# kubectl rollout undo deployments/kubernetes-bootcampdeployment.apps/kubernetes-bootcamp rolled back root@ymx-ubuntu:~# kubectl get pods NAME READY STATUS RESTARTS AGE kubernetes-bootcamp-684bd555bb-hfkk7 1/1 Running 0 3m22s kubernetes-bootcamp-684bd555bb-sxsg9 1/1 Running 0 3m8s root@ymx-ubuntu:~# kubectl describe pods Name: kubernetes-bootcamp-684bd555bb-hfkk7 Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Sat, 14 May 2022 10:18:39 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=684bd555bb Annotations: <none> Status: Running IP: 172.17.0.3 IPs: IP: 172.17.0.3 Controlled By: ReplicaSet/kubernetes-bootcamp-684bd555bb ...... Name: kubernetes-bootcamp-684bd555bb-sxsg9 Namespace: default Priority: 0 Node: minikube/192.168.49.2 Start Time: Sat, 14 May 2022 10:18:53 +0800 Labels: app=kubernetes-bootcamp pod-template-hash=684bd555bb Annotations: <none> Status: Running IP: 172.17.0.6 IPs: IP: 172.17.0.6 Controlled By: ReplicaSet/kubernetes-bootcamp-684bd555bb ...... 复制代码
7 小总结下吧
经过了实际的操作,我们终于知道了在Kubernetes集群中是如何将自己的应用,也可以说是打包好的Docker镜像在集群中进行灵活运用的,这种方式无论是相比虚拟机部署还是容器部署都更加的灵活高效,当然这种方式是基于容器部署的,在此基础上能够让我们更好的对容器进行集成和管理。
当然本文是基于Kubernetes官方文档(kubernetes.io/zh/docs)进行的…
参考:
本文图片均来自:kubernetes.io/zh/docs/tut…