websocket 2 rest api

需要开发一个prometheus 的exporter 使用jmespath 获取对应metrics的数据，并进行转换处理，但是因为那个服务
提供的接口是通过websoket 的实时api，所以基于node 进行了简单的包装处理，暴露为一个直接可以使用的rest api
同时保留了数据的实效性

实现技术

很简单，通过express 暴露一个rest api，通过websocket client 连接已有websocket 服务，并使用全局变量存储数据即可
后边对应的exporter 直接获取数据进行处理就可以了

项目结构

代码结构

├── Dockerfile

├── README.md

├── app.env

├── docker-compose.yaml

├── index.js

├── package.json

代码说明
Dockerfile

FROM node:alpine

WORKDIR /app

COPY . /app

LABEL NORE="ws 2 rest"

ENV NODE_ENV=production

ENV WSADDRESS=ws://localhost:7890/

LABEL AUTHOR="1141591465@qq.com"

EXPOSE 3000

RUN yarn

CMD [ "yarn", "start"]

index.js: 核心处理代码，和简单，就是包装了websocket 服务

const express = require('express')

const app = express()

var realtimeMetrics ={};

const WebSocketClient = require('websocket').client;

// 通过环境变量配置websocket 服务的地址

const wsAddress = process.env.WSADDRESS || "ws://localhost:7890/"

const client = new WebSocketClient();

client.on('connectFailed', function(error) {

    console.log('Connect Error: ' + error.toString());

});

client.on('connect', function(connection) {

    console.log('WebSocket Client Connected');

    connection.on('error', function(error) {

        console.log("Connection Error: " + error.toString());

    });

    connection.on('close', function() {

        console.log('echo-protocol Connection Closed');

    });

    client.onopen = function() {

        console.log('WebSocket Client Connected');

        function sendNumber() {

            if (client.readyState === client.OPEN) {

                var number = Math.round(Math.random() * 0xFFFFFF);

                client.send(number.toString());

                setTimeout(sendNumber, 1000);

            }

        }

        sendNumber();

    };

    connection.on('message', function(message) {

        if (message.type === 'utf8') {

            console.log("Received: '" + message.utf8Data + "'");

            realtimeMetrics = message.utf8Data;

        }

    });

});

client.connect(wsAddress);

app.get('/', function (req, res) {

    res.contentType("application/json")

    res.send(realtimeMetrics)

})

app.listen(3000)

pacakge.json 内容: 主要是npn 包的引用以及npm script 配置，这个包含了几个多余的依赖，但是不影响使用
可以直接删除

{

  "dependencies": {

    "express": "^4.16.4",

    "jmespath": "^0.15.0",

    "node-fetch": "^2.3.0",

    "websocket": "^1.0.28"

  },

  "scripts": {

    "start":"node index.js"

  }

}

docker-compose.yaml

version: "3"

services:

    ws2rest:

      image: dalongrong/simplews2rest

      build: ./

      ports:

      - "3000:3000"

      env_file:

      - app.env

app.env ：主要是方便扩展的

WSADDRESS=ws://server:port/

使用此服务的demo

docker-compose 文件

version: "3"

services:

  metrics:

   image: dalongrong/promethues-jmespath-exporter

   volumes:

   - "./conf/config.yaml:/etc/prometheus-jsonpath-exporter/config.yml"

   ports:

   - "9158:9158"

   command: /etc/prometheus-jsonpath-exporter/config.yml

  ws2rest:

   image: dalongrong/simplews2rest

   environment:

   - "WSADDRESS=ws://server:7890/"

   ports:

   - "3000:3000"

参考资料

https://github.com/rongfengliang/ws-rest
https://github.com/rongfengliang/promethues-jmespath-exporter-demo

巴特西

websocket 2 rest api

实现技术

项目结构

使用此服务的demo

参考资料

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