Cloud Functions for Firebase: 'Error: could not handle the request'

Question

I feel like pulling my hair out; this is either super simple and i'm having brain freeze or it is not that simple.

What I want

I am trying to unshorten a shortened URL using firebase, when a user goes to:
myapp.firebaseappurl.com/url/SHORTENEDLINK
SO wont let me add a shortened URL

I would like the output to be:

{
  "url": "https://stackoverflow.com/questions/45420989/sphinx-search-how-to-use-an-empty-before-match-and-after-match"
}

What I have tried

firebase.json file:

{
  "hosting": {
    "public": "public",
    "rewrites": [ {
    "source": "/url/:item",
      "destination": "/url/:item"
    } ]
  }
}

index.js file:

const functions = require('firebase-functions');

exports.url = functions.https.onRequest((requested, response) => {

    var uri = requested.url;
    request({
        uri: uri,
        followRedirect: true
      },
      function(err, httpResponse) {
        if (err) {
          return console.error(err);
        }
        response.send(httpResponse.headers.location || uri);
      }
    );

});

Result

When I go to myapp.firebaseappurl.com/url/SHORTENEDLINK I get the following:

Error: could not handle the request

Answer 1

You are seeing Error: could not handle the request since there probably was an exception and it timed out.

Check your logs using:

firebase functions:log

Refer docs for more details

Here's how I got URL unshortening to work

const functions = require('firebase-functions');

const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

const http = require('http');
const urlP = require('url');

const unshorten = (url, cb) => {
  const _r = http.request(
    Object.assign(
      {},
      urlP.parse(url),
      {
        method: 'HEAD',
      }
    ),
    function(response) {
      cb(null, response.headers.location || url);
    }
  );
  _r.on('error', cb);
  _r.end();
};

const resolveShortUrl = (uri, cb) => {
  unshorten(uri, (err, longUrl) => {
    if (longUrl === uri) {
      cb(null, longUrl);
    } else {
      resolveShortUrl(longUrl, cb);
    }
  });
};

exports.url = functions.https.onRequest((requested, response) => {
  var uri = requested.query.url;
  resolveShortUrl(uri, (err, url) => {
    if (err) {
      // handle err
    } else {
      response.send({ url });
    }
  });
});

You can follow the hello world example straight away and use the above code as your function.

Above code uses HEAD requests to peek into 'Location` field of the headers and decides if the url can be further unshortened.

This is lighter as HEAD requests ask for no body (thereby avoiding body parsing). Also, no third party lib required!

Also note that the url passed as a query param. So the request would be

http://<your_firebase_server>/url?url=<short_url>

Saves you the trouble of URL re-writes. Plus semantically makes a little more sense.