Add ability to use context matching function

[earthboundkid]

What problem does this feature solve?

The following example is in the README for http-proxy-middleware, but AFAICT, cannot be implemented in proxy-module:

var filter = function(pathname, req) {
  return pathname.match('^/api') && req.method === 'GET';
};

var apiProxy = proxy(filter, { target: 'http://www.example.org' });

I would like the ability to use context matching functions.

What does the proposed changes look like?

On a user level it might look like:

  proxy: {
    [(pathname, req) => pathname.match('^/api') && req.method === 'GET']: { target: 'http://www.example.org' }
  },

_{This feature request is available on Nuxt community (#c30)}

[bjbr-dev]

I've just got this working for my own project by using this syntax:

proxy: [
  [
      (pathname, req) => pathname.match('^/api') && req.method === 'GET',
      { target: 'http://localhost:8000/' }
  ]
]

Basically, use the longhand syntax (the outer array instead of an object), and use a tuple of [selector, options] where selector can be a string or a function.

[Hulkmaster]

doesn't seem to work during SSR
axios ignores these rules

[floschne]

I also think this would be a very nice feature since it would support dynamic contexts, i.e., context set at build time. For example, when running the app behind a reverse-proxy with a specific context path, the context path needs to be hard ooded and cannot be set e.g. via an env variable.

I'm not into this project but I guess it's kinda easy to implement by updating src/options.ts line 4 and 24 so that it does not only use the key as context but provide an own entry in the dict with the value either a function or string literal

[floschne]

I'm able to use custom matching and custom rewrite by doing the following: (you can omit the docker part of course)

const proxyConfig = () => {
  // ------------------ proxy config for API ----------------------
  let apiProxyTarget = ''
  const ctxPath = process.env.APP_CTX_PTH || '/'
  if (process.env.APP_DEPLOY === 'docker') {
    const dockerApiHost = process.env.API_HOST
    const dockerApiPort = process.env.API_PORT

    apiProxyTarget = 'http://' + dockerApiHost + ':' + dockerApiPort + '/'
  } else {
    apiProxyTarget = 'http://localhost:8081/'
  }

  // https://github.com/chimurai/http-proxy-middleware/blob/master/recipes/pathRewrite.md#custom-rewrite-function
  const apiCustomRewrite = (pth, req) => {
    const ctx = `${ctxPath}api/`
    return pth.replace(ctx, '/')
  }

  // https://github.com/chimurai/http-proxy-middleware#context-matching
  const apiCustomMatching = (pathname, req) => {
    const ctx = `${ctxPath}api/`
    return pathname.match(ctx)
  }

  return [
    [
      apiCustomMatching,
      {
        target: apiProxyTarget,
        pathRewrite: apiCustomRewrite,
      },
    ],
}

proxy: proxyConfig()