无法向 Eureka 服务器注册 React 应用程序

如何解决无法向 Eureka 服务器注册 React 应用程序

错误：

访问获取 'http://127.0.0.1:8761/eureka/apps/auth0-react-sample' 来自原点 'http://localhost:3000' 已被 CORS 策略阻止：响应 预检请求未通过访问控制检查：否 请求中存在“Access-Control-Allow-Origin”标头 资源。如果不透明的响应满足您的需求，请设置请求的 模式为 'no-cors' 以在禁用 CORS 的情况下获取资源。

代码：

Index.js (React 应用)

    const PORT = process.env.PORT || 3000;
    const eurekaHelper = require('./eureka-helper/eureka-helper');
    
    const Eureka = require('eureka-js-client').Eureka;
    
    // const PORT = 3000;
    // const HOST = '0.0.0.0';
    
    // example configuration
    const client = new Eureka({
      // application instance information
      instance: {
        app: 'auth0-react-sample',hostName: 'localhost',ipAddr: 'localhost',//statusPageUrl: 'http://localhost:3000/',port: 3000,vipAddress: 'auth0-react-sample',dataCenterInfo: {
          name: 'default',},registerWithEureka: true,fetchRegistry: true,eureka: {
        // eureka server host / port
        host: 'localhost',port: 8761,servicePath: '/eureka/apps',});
    
    
    
    // Listen on a specific host via the HOST environment variable
    var host = process.env.HOST || '0.0.0.0';
    // Listen on a specific port via the PORT environment variable
    var port = process.env.PORT || 3000;
    
    
    const onRedirectCallback = (appState) => {
      history.push(
        appState && appState.returnTo ? appState.returnTo : window.location.pathname
      );
    };
    
    // Please see https://auth0.github.io/auth0-react/interfaces/auth0provideroptions.html
    // for a full list of the available properties on the provider
    const config = getConfig();
    
    const providerConfig = {
      domain: config.domain,clientId: config.clientId,...(config.audience ? { audience: config.audience } : null),redirectUri: window.location.origin,onRedirectCallback,};
    
    
    client.start(error=>{
      console.log(error || 'NodeJS Eureka started');
      ReactDOM.render(
        <Auth0Provider {...providerConfig}>
          <App />
        </Auth0Provider>,document.getElementById("root")
      );
    });
    
    eurekaHelper.registerWithEureka('auth0-react-sample',PORT);
    

serviceWorker.unregister();

eureka-helper.js

    const Eureka = require('eureka-js-client').Eureka;
const eurekaHost = (process.env.EUREKA_CLIENT_SERVICEURL_DEFAULTZONE || '127.0.0.1');
const eurekaPort = 8761;
const hostName = (process.env.HOSTNAME || 'localhost')
const ipAddr = '127.0.0.1';

exports.registerWithEureka = function(appName,PORT) {
    const client = new Eureka({
    instance: {
      app: appName,hostName: hostName,ipAddr: ipAddr,port: {
        '$': PORT,'@enabled': 'true',vipAddress: appName,dataCenterInfo: {
        '@class': 'com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo',name: 'MyOwn',//retry 10 time for 3 minute 20 seconds.
    eureka: {
      host: eurekaHost,port: eurekaPort,servicePath: '/eureka/apps/',maxRetries: 10,requestRetryDelay: 2000,})

client.logger.level('debug')

client.start( error => {
    console.log(error || "user service registered")
});



function exitHandler(options,exitCode) {
    if (options.cleanup) {
    }
    if (exitCode || exitCode === 0) console.log(exitCode);
    if (options.exit) {
        client.stop();
    }
}

client.on('deregistered',() => {
    process.exit();
    console.log('after deregistered');
})

client.on('started',() => {
  console.log("eureka host  " + eurekaHost);
})

process.on('SIGINT',exitHandler.bind(null,{exit:true}));
};