Google Cloud Functions enable CORS?

Question

I just finished the Hello World Google Cloud Functions tutorial and received the following response headers:

Connection → keep-alive
Content-Length → 14
Content-Type → text/plain; charset=utf-8
Date → Mon, 29 Feb 2016 07:02:37 GMT
Execution-Id → XbT-WC9lXKL-0
Server → nginx

How can I add the CORS headers to be able to call my function from my website?

Answer 1

In the python environment, you can use the flask request object to manage CORS requests.

def cors_enabled_function(request):
    if request.method == 'OPTIONS':
        # Allows GET requests from any origin with the Content-Type
        # header and caches preflight response for an 3600s
        headers = {
            'Access-Control-Allow-Origin': '*',
            'Access-Control-Allow-Methods': 'GET',
            'Access-Control-Allow-Headers': 'Content-Type',
            'Access-Control-Max-Age': '3600'
        }

        return ('', 204, headers)

    # Set CORS headers for the main request
    headers = {
        'Access-Control-Allow-Origin': '*'
    }

    return ('Hello World!', 200, headers)

See the gcloud docs for more.

Answer 2

here we go:

exports.helloWorld = function helloWorld(req, res) {  
  res.set('Access-Control-Allow-Origin', "*")
  res.set('Access-Control-Allow-Methods', 'GET, POST')
  res.status(200).send('weeee!);
};

then you can jquery/whatever it as usual:

$.get(myUrl, (r) => console.log(r))

Answer 3

I've just created webfunc. It's a lightweight HTTP server that supports CORS as well as routing for Google Cloud Functions. Example:

const { serveHttp, app } = require('webfunc')

exports.yourapp = serveHttp([
  app.get('/', (req, res) => res.status(200).send('Hello World')),
  app.get('/users/{userId}', (req, res, params) => res.status(200).send(`Hello user ${params.userId}`)),
  app.get('/users/{userId}/document/{docName}', (req, res, params) => res.status(200).send(`Hello user ${params.userId}. I like your document ${params.docName}`)),
])

In your project's root, simply add a appconfig.json that looks like this:

{
  "headers": {
    "Access-Control-Allow-Methods": "GET, HEAD, OPTIONS, POST",
    "Access-Control-Allow-Headers": "Origin, X-Requested-With, Content-Type, Accept",
    "Access-Control-Allow-Origin": "*",
    "Access-Control-Max-Age": "1296000"
  }
}

Hope this helps.

Answer 4

You can use the CORS express middleware.

package.json

npm install express --save
npm install cors --save

index.js

'use strict';

const functions = require('firebase-functions');
const express = require('express');
const cors = require('cors')({origin: true});
const app = express();

app.use(cors);
app.get('*', (req, res) => {
    res.send(`Hello, world`);
});

exports.hello = functions.https.onRequest(app);

Answer 5

If you are looking for an actual code sample (and your question is still relevant), I wrote a blog post about that: https://mhaligowski.github.io/blog/2017/03/10/cors-in-cloud-functions.html.

Answer 6

I'm the product manager for Google Cloud Functions. Thanks for your question, this has been a popular request.

We don't have anything to announce just yet, but we're aware of several enhancements that need to be made to the HTTP invocation capabilities of Cloud Functions and we'll be rolling out improvements to this and many other areas in future iterations.

UPDATE:

We've improved the way you deal with HTTP in Cloud Functions. You now have full access to the HTTP Request/Response objects so you can set the appropriate CORS headers and respond to pre-flight OPTIONS requests (https://cloud.google.com/functions/docs/writing/http)