multi targets !

[sdellava]

It can appear strange, but i need to proxy a request to many target and send back the first correct response to the caller.

In a custom script I've done in this way:

const race = (path, options, providers, fallbackProvider) => {
  const promiseArray = [];
  let errors = 0;

  providers.forEach((provider) => {
    const url = provider + path;

    promiseArray.push(
      new Promise(async (resolve, reject) => {
        try {
          const responseHTTP = await fetch(url, options);
          const status = responseHTTP.status;
          const response = JSON.parse(await responseHTTP.text());
          response ? resolve({ response, status }) : null;
        } catch (error) {
          console.log(`error`, error);
          errors += 1;

          if (promiseArray.length === errors) {
            console.log("GOING TO REJECT");
            reject(error);
          }
        }
      })
    );
  });

  return Promise.race(promiseArray)
    .then(async (result) => {
      console.log(`result`, result);
      return result;
    })
    .catch(async (err) => {
      console.log(`ALL REJECTED`, err);
      try {
        const url = fallbackProvider + path;
        const responseHTTP = await fetch(url, options);
        const status = responseHTTP.status;
        const response = JSON.parse(await responseHTTP.text());
        console.log(`response`, response);
        console.log(`status`, status)
        return { response, status };
      } catch (error) {
        return Promise.reject(error);
      }
    });
};

race(path, options, providers, fallbackProvider)

The function create a promise for each provider and if every providers fails than the functions try the fallback provider

The first valid response si sent back to the requester and the other responses are ignored.

Unfortunately this approach do not works correctly for some kind of requests so I need to use http-proxy-middleware.

Any suggestion on how to implement the same logic with the proxy?

[chimurai]

That's beyond the scope of http-proxy-middleware.