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406 lines
15 KiB
Markdown
406 lines
15 KiB
Markdown
---
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title: '基于 Kubernetes 部署 node.js APP'
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tag: 'Kubernetes'
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createTime: '2019-08-25'
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author: 'Leo Liu'
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snapshot: 'https://pek3b.qingstor.com/kubesphere-docs/png/20190930145646.png'
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---
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### 什么是 Kubernetes
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Kubernetes 是一个开源容器编排引擎，可以帮助开发者或运维人员部署和管理容器化的应用，能够轻松完成日常开发运维过程中诸如 滚动更新，横向自动扩容，服务发现，负载均衡等需求。[了解更多](https://kubernetes.io/docs/concepts/overview/what-is-kubernetes/)
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### 安装 Kubernetes
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可以通过快速安装 kubernetes 集群：
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- [KubeSphere Installer](https://github.com/kubesphere/kubesphere)
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- [minikube](https://kubernetes.io/docs/setup/learning-environment/minikube/)
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- [kubeadm](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/)
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### Kubernetes 术语介绍
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#### [Pod](https://kubernetes.io/docs/concepts/workloads/pods/pod/)
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Pod 是 Kubernetes 最小调度单位，是一个或一组容器的集合。
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#### [Deployment](https://kubernetes.io/docs/concepts/workloads/controllers/deployment/)
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提供对 Pod 的声明式副本控制。指定 Pod 模版，Pod 副本数量, 更新策略等。
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#### [Service](https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/)
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Service 定义了 Pod 的逻辑分组和一种可以访问它们的策略。借助Service，应用可以方便的实现服务发现与负载均衡。
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#### [Label & Selector](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/)
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Kubernetes 中使用 Label 去关联各个资源。
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1. 通过资源对象(Deployment, etc.)上定义的 Label Selector 来筛选 Pod 数量。
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2. 通过 Service 的 Label Selector 来选择对应的 Pod， 自动建立起每个 Service 到对应 Pod 的请求转发路由表。
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3. 通过对某些 Node 定义特定的 Label，并且在 Pod 中添加 NodeSelector 属性，可以实现 Pod 的定向调度(运行在哪些节点上)。
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### Nodejs 模板项目
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[node-express-realworld-example-app](https://github.com/gothinkster/node-express-realworld-example-app) 是一款 node.js 编写的后端示例应用。使用 Express 作为网络框架，使用 mongodb 持久化数据，使用 jwt 作用户认证等。
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#### 项目分析
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1. 分析 package.json, 将使用 ``npm start`` 作为容器启动命令，并依赖于一个 ``realworld-mongo`` 的容器服务。
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```json
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{
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"scripts": {
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"mongo:start": "docker run --name realworld-mongo -p 27017:27017 mongo & sleep 5",
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"start": "node ./app.js",
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"dev": "nodemon ./app.js",
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"test": "newman run ./tests/api-tests.postman.json -e ./tests/env-api-tests.postman.json",
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"stop": "lsof -ti :3000 | xargs kill",
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"mongo:stop": "docker stop realworld-mongo && docker rm realworld-mongo"
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},
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}
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```
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2. 全局搜索 ``process.env.``并分析代码, 生产环境需要 的环境变量有:
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```shell
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NODE_ENV # 应设置为 production
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MONGODB_URI # mondodb 服务路径
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PORT # nodejs 服务端口, 默认3000
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SECRET # jwt token 的私钥
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```
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#### 在项目根目录添加 Dockerfile:
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```Dockerfile
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FROM mhart/alpine-node:8
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WORKDIR /root/demo
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COPY ./package.json .
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RUN npm install
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COPY . .
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EXPOSE 3000
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CMD ["npm", "start"]
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```
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#### 打包镜像
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```shell
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docker build -t example-app .
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```
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#### 推送镜像到 [Docker Hub](https://hub.docker.com/)
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```shell
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docker login -u $DOCKERHUB_USER -p $DOCKERHUB_PASSWORD
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docker tag example-app $DOCKERHUB_USER/example-app:v0.1.0
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docker push $DOCKERHUB_USER/example-app:v0.1.0
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```
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### 部署 MongoDB
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此应用将分为两个服务部署，一个是包含 Nodejs 主程序的 example-app 服务，一个提供存储的 mognodb 服务。
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mongodb 使用 https://hub.docker.com/_/mongo 作为镜像，因为有持久化数据，在单节点模式下可以使用 HostPath 挂载存储（多节点模式或挂载 PVC 存储形式推荐使用 [KubeSphere](https://kubesphere.io/) 部署集群, 省去繁琐的配置），通过 Service 将服务暴露到 k8s 内部。
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mongodb.yaml
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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namespace: default
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labels: &ref_0
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app: mongodb
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name: mongodb
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spec:
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replicas: 1
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selector:
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matchLabels: *ref_0
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template:
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metadata:
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labels: *ref_0
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spec:
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containers:
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- name: container-ur9rxw
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image: mongo
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imagePullPolicy: IfNotPresent
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ports:
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- name: http-mongo
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protocol: TCP
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containerPort: 27017
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volumeMounts:
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- readOnly: false
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mountPath: /data/db
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name: mongodb
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serviceAccount: default
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volumes:
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- hostPath:
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path: /data/db
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type: DirectoryOrCreate
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name: mongodb-pvc
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strategy:
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rollingUpdate:
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maxSurge: 1
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maxUnavailable: 1
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type: RollingUpdate
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```
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配置文件中主要包含：
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1. 定义了 Pod 运行时的镜像 ``mongo``，
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2. 暴露 mognodb 服务到 27017 端口
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3. 声明了一个 hostPath，将主机上的 /data/db 路径挂载到容器的 /data/db 路径上(mongodb 默认数据存放路径)。
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在 kubernetes 集群中执行 kubectl 部署
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```shell
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kubectl apply -f mongodb.yaml
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```
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查看 pod 运行情况：
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```shell
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root@i-auleonob:/home/ubuntu# kubectl get pods
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NAME READY STATUS RESTARTS AGE
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mongodb-54f949cb5c-r48bj 1/1 Running 0 42s
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```
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pod 已成功运行起来
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查看 mongodb 服务日志:
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```shell
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root@i-auleonob:/home/ubuntu# kubectl logs mongodb-54f949cb5c-r48bj
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2019-09-09T14:05:05.127+0000 I CONTROL [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'
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2019-09-09T14:05:05.132+0000 I CONTROL [initandlisten] MongoDB starting : pid=1 port=27017 dbpath=/data/db 64-bit host=mongodb-54f949cb5c-r48bj
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2019-09-09T14:05:05.132+0000 I CONTROL [initandlisten] db version v4.2.0
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2019-09-09T14:05:05.132+0000 I CONTROL [initandlisten] git version: a4b751dcf51dd249c5865812b390cfd1c0129c30
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2019-09-09T14:05:05.132+0000 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.1.1 11 Sep 2018
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...
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2019-09-09T14:05:06.180+0000 I NETWORK [initandlisten] Listening on 0.0.0.0
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2019-09-09T14:05:06.180+0000 I NETWORK [initandlisten] waiting for connections on port 27017
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...
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```
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从日志可以看到 mongodb 已成功启动，并监听 27017 端口, 但此时在集群中还无法访问该端口，需要创建一个服务将端口映射到集群。
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### 创建 MongoDB 服务
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mongodb-service.yaml
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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namespace: default
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labels: &ref_0
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app: mongodb
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name: mongodb-service
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spec:
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type: ClusterIP
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sessionAffinity: None
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selector: *ref_0
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ports:
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- name: http-mongo
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protocol: TCP
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port: 27017
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targetPort: 27017
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```
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在 kubernetes 集群中执行 kubectl 创建服务
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```shell
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kubectl apply -f mongodb-service.yaml
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```
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查看服务详情
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```shell
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root@i-auleonob:/home/ubuntu# kubectl describe svc/mongodb-service
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Name: mongodb-service
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Namespace: default
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Labels: app=mongodb
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Annotations: kubectl.kubernetes.io/last-applied-configuration:
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{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"mongodb"},"name":"mongodb-service","namespace":"default"...
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Selector: app=mongodb
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Type: ClusterIP
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IP: 10.102.156.99
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Port: http-mongo 27017/TCP
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TargetPort: 27017/TCP
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Endpoints: 192.168.219.10:27017
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Session Affinity: None
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Events: <none>
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```
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透过 [Kubernetes DNS](https://kubernetes.io/docs/concepts/services-networking/service/#dns)，在集群内部可以使用 ``mongodb-service.default:27017`` 访问到 mongodb 服务。
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### 部署 Example App
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example-app 无需挂载存储卷，但容器的启动时需要必要的环境变量。在 env 中填入必要的环境变量，通过 mongodb-service.default 来访问 mongodb 服务。该端口无需暴露到主机上，service 类型选择使用 [ClusterIP](https://kubernetes.io/docs/concepts/services-networking/service/#publishing-services-service-types)。
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example-app.yaml
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```yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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namespace: default
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labels:
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version: v1
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app: example-app
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name: example-app-v1
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spec:
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replicas: 1
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selector:
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matchLabels:
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version: v1
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app: example-app
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template:
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metadata:
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labels:
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version: v1
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app: example-app
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spec:
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containers:
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- name: container-l6cx0m
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image: leoendlessx/example-app:v0.1.0
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imagePullPolicy: IfNotPresent
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ports:
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- name: http-app
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protocol: TCP
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containerPort: 3000
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env:
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- name: NODE_ENV
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value: production
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- name: MONGODB_URI
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value: mongodb-service.default # 使 用kubernetes 内部 DNS 来访问 mongodb 服务
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- name: SECRET
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value: asecretkey
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serviceAccount: default
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strategy:
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type: RollingUpdate
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rollingUpdate:
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maxUnavailable: 25%
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maxSurge: 25%
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```
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在 kubernetes 集群中执行 kubectl 部署
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```shell
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kubectl apply -f example-app.yaml
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```
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查看 Pod 状态及日志
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```shell
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root@i-auleonob:/home/ubuntu# kubectl get pods
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NAME READY STATUS RESTARTS AGE
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example-app-v1-5678d8db79-7nhkd 1/1 Running 0 26s
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mongodb-54f949cb5c-r48bj 1/1 Running 0 71m
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root@i-auleonob:/home/ubuntu# kubectl logs example-app-v1-5678d8db79-7nhkd
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> conduit-node@1.0.0 start /root/demo
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> node ./app.js
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Warning: connect.session() MemoryStore is not
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designed for a production environment, as it will leak
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memory, and will not scale past a single process.
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Listening on port 3000
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```
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example-app 程序已成功启动，现在需将服务暴露主机节点上访问，以便主机网络将端口映射到外网。service 类型选择 [NodePort](https://kubernetes.io/docs/concepts/services-networking/service/#nodeport)
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### 创建 Example App 服务到并暴露到主机
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```yaml
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apiVersion: v1
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kind: Service
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metadata:
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namespace: default
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labels: &ref_0
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version: v1
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app: example-app
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name: example-app
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spec:
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type: NodePort
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sessionAffinity: ClientIP
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selector: *ref_0
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ports:
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- name: http-app
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protocol: TCP
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port: 3000
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targetPort: 3000
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```
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在 kubernetes 集群中执行 kubectl 创建服务
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```shell
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kubectl apply -f example-app-service.yaml
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```
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查看服务详情
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```shell
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root@i-auleonob:/home/ubuntu# kubectl describe svc/example-app
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Name: example-app
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Namespace: default
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Labels: app=example-app
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version=v1
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Annotations: kubectl.kubernetes.io/last-applied-configuration:
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{"apiVersion":"v1","kind":"Service","metadata":{"annotations":{},"labels":{"app":"example-app","version":"v1"},"name":"example-app","names...
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Selector: app=example-app,version=v1
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Type: NodePort
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IP: 10.106.109.178
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Port: http-app 3000/TCP
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TargetPort: 3000/TCP
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NodePort: http-app 30375/TCP
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Endpoints: 192.168.219.48:3000
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Session Affinity: ClientIP
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External Traffic Policy: Cluster
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Events: <none>
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```
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在节点上访问：
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```shell
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root@i-auleonob:/home/ubuntu# curl 127.0.0.1:30375
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{"errors":{"message":"Not Found","error":{}}}
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```
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可见 example-app 可以正常访问，不过仍需要确认是否能正常访问 mongodb。
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> example-app 容器需要等待 mongodb service 可用时, 才可以正常启动。在 mongodb service 可用后, 手动删除旧的 example-app Pod 即可。
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### 测试 Example App 服务
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#### 注册用户
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```shell
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curl -X POST \
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'http://127.0.0.1:30375/api/users' \
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-H 'Content-Type: application/json' \
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-H 'X-Requested-With: XMLHttpRequest' \
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-H 'cache-control: no-cache' \
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-d '{"user":{"email":"john@jacob.com", "password":"johnnyjacob", "username":"johnjacob"}}'
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{"user":{"username":"johnjacob","email":"john@jacob.com","token":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjVkNzY3MmMzMzdjNGI5MTAwMGVhZmIzYyIsInVzZXJuYW1lIjoiam9obmphY29iIiwiZXhwIjoxNTczMjI3NzE1LCJpYXQiOjE1NjgwNDM3MTV9.24OGisacl8-n4SooYr8kdcAOYTBvz27sC1mUyU3VkKM"}}
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```
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#### 登录
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```shell
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curl -X POST \
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'http://127.0.0.1:30375/api/users/login' \
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-H 'Content-Type: application/json' \
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-H 'X-Requested-With: XMLHttpRequest' \
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-H 'cache-control: no-cache' \
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-d '{"user":{"email":"john@jacob.com", "password":"johnnyjacob"}}'
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{"user":{"username":"johnjacob","email":"john@jacob.com","token":"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjVkNzY3MmMzMzdjNGI5MTAwMGVhZmIzYyIsInVzZXJuYW1lIjoiam9obmphY29iIiwiZXhwIjoxNTczMjI3ODcwLCJpYXQiOjE1NjgwNDM4NzB9.a5p0mCLZLSNbTCECjK9j-5hrgg-tA7mI5iENKdik5Xc"}}
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```
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#### 创建 Article
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```shell
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curl -X POST \
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'http://127.0.0.1:30375/api/articles' \
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-H 'Authorization: Token eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjVkNzY3MmMzMzdjNGI5MTAwMGVhZmIzYyIsInVzZXJuYW1lIjoiam9obmphY29iIiwiZXhwIjoxNTczMjI3ODcwLCJpYXQiOjE1NjgwNDM4NzB9.a5p0mCLZLSNbTCECjK9j-5hrgg-tA7mI5iENKdik5Xc' \
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-H 'Content-Type: application/json' \
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-H 'X-Requested-With: XMLHttpRequest' \
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-H 'cache-control: no-cache' \
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-d '{"article":{"title":"How to train your dragon", "description":"Ever wonder how?", "body":"Very carefully.", "tagList":["dragons","training"]}}'
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{"article":{"slug":"how-to-train-your-dragon-estl69","title":"How to train your dragon","description":"Ever wonder how?","body":"Very carefully.","createdAt":"2019-09-09T15:46:26.935Z","updatedAt":"2019-09-09T15:46:26.935Z","tagList":["dragons","training"],"favorited":false,"favoritesCount":0,"author":{"username":"johnjacob","image":"https://static.productionready.io/images/smiley-cyrus.jpg","following":false}}}
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```
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#### 获取所有 Articles
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```shell
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curl -X GET \
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'http://127.0.0.1:30375/api/articles' \
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-H 'Authorization: Token eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjVkNzY3MmMzMzdjNGI5MTAwMGVhZmIzYyIsInVzZXJuYW1lIjoiam9obmphY29iIiwiZXhwIjoxNTczMjI3ODcwLCJpYXQiOjE1NjgwNDM4NzB9.a5p0mCLZLSNbTCECjK9j-5hrgg-tA7mI5iENKdik5Xc' \
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-H 'Content-Type: application/json' \
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-H 'X-Requested-With: XMLHttpRequest' \
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-H 'cache-control: no-cache'
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{"articles":[{"slug":"how-to-train-your-dragon-estl69","title":"How to train your dragon","description":"Ever wonder how?","body":"Very carefully.","createdAt":"2019-09-09T15:46:26.935Z","updatedAt":"2019-09-09T15:46:26.935Z","tagList":["dragons","training"],"favorited":false,"favoritesCount":0,"author":{"username":"johnjacob","image":"https://static.productionready.io/images/smiley-cyrus.jpg","following":false}}],"articlesCount":1}
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```
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通过测试可发现 example-app 与 mongodb 服务运行正常。
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<!-- ### 使用 KubeSphere UI 部署服务
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[KubeSphere](https://kubesphere.io/) 是一款简单易用的 kubernetes 开源发行版, 可视化的部署操作大大降低运维难度。 -->
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