测试环境、开发环境 （vue2.9 ）

需求： vue web页面axios.get可以跨域访问http://192.168.10.30:8143/api/puppet api
动作：

1. index.js 中增加proxyTable: 字段
   2.vue文件中get(‘绝对路径‘)使用绝对路径，仅用uri无效

index.js

'use strict'
// Template version: 1.3.1
// see http://vuejs-templates.github.io/webpack for documentation.
const path = require('path')
module.exports = {
  dev: {
    assetsSubDirectory: 'static',
    assetsPublicPath: '/',
    proxyTable: {
      '/api/puppet': {
          target: `http://192.168.10.30:8143/api/puppet`,
          changeOrigin: true,
          //pathRewrite: {  路径转换时才须定义次选项如：/api 转/bpi
           //   '^/api/puppet' : '/bpi'
          //}
      }
    },
    host: '0.0.0.0', // can be overwritten by process.env.HOST
    port: 8087, // can be overwritten by process.env.PORT, if port is in use, a free one will be determined
    autoOpenBrowser: false,
    errorOverlay: true,
    notifyOnErrors: true,
    poll: false, // https://webpack.js.org/configuration/dev-server/#devserver-watchoptions-
    useEslint: true,
    showEslintErrorsInOverlay: false,
    devtool: 'cheap-module-eval-source-map',
    cacheBusting: true,
    cssSourceMap: true
  },

vue 文件中

     pulldata() {
        this.axios.get("http://127.0.0.1:8087/api/puppet")
          .then(function (response) {
            console.log(9099)
            console.log(response);
          })
      },

线上环境、生产环境

注意事项：
在跨域的情况下，跨域共享标准规范要求先用 OPTIONS 方法发起预检请求（preflight request），获知服务端是否允许该跨域请求。服务器确认允许之后，才发起实际的 HTTP 请求，所以后端服务器或者代理服务器必须支持options请求返回204，即可支持跨域请求

1.通过nginx代理实现
 server {
        listen       8087;
        server_name  _;
        index index.html;
        root /opt/dist;
        location /api/puppet/ {
            if ($request_method = 'OPTIONS') {
                add_header Access-Control-Allow-Origin *;
                add_header Access-Control-Allow-Credentials true;
                add_header Access-Control-Allow-Methods 'OPTIONS, GET, POST, PUT, DELETE, UPDATE';
                add_header Content-Type 'application/json; charset=utf-8';
                add_header Access-Control-Allow-Headers 'Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With';
                return 204;
            }

            proxy_pass http://1.9.1.3:8143;  
        }
        location / {
             root /opt/dist;
             try_files $uri $uri/ /index.html;
             expires 30d;
        }
}

2.设置允许跨域响应头
    origin := c.Request.Header.Get("origin") //请求头部
    if len(origin) == 0 {
        origin = c.Request.Header.Get("Origin")
    }
        //接收客户端发送的origin （重要！）
        c.Writer.Header().Set("Access-Control-Allow-Origin", origin)
        //允许客户端传递校验信息比如 cookie (重要)
        c.Writer.Header().Set("Access-Control-Allow-Credentials", "true")
        c.Writer.Header().Set("Access-Control-Allow-Headers", "Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, accept, origin, Cache-Control, X-Requested-With")
        //服务器支持的所有跨域请求的方法
        c.Writer.Header().Set("Access-Control-Allow-Methods", "OPTIONS, GET, POST, PUT, DELETE, UPDATE")
        c.Writer.Header().Set("Content-Type", "application/json; charset=utf-8")
        // 设置预验请求有效期为 86400 秒
        c.Writer.Header().Set("Access-Control-Max-Age", "86400")
    if c.Request.Method == "OPTIONS" {
            c.AbortWithStatus(204)
            return
        }
    c.Next()