Wide-open CORS config for nginx

cors-nginx.conf

#
# Wide-open CORS config for nginx
#
location / {

     if ($request_method = 'OPTIONS') {

        add_header 'Access-Control-Allow-Origin' '*';
        
        #
        # Om nom nom cookies
        #

        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        
        #
        # Custom headers and headers various browsers *should* be OK with but aren't
        #

        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';
        
        #
        # Tell client that this pre-flight info is valid for 20 days
        #

        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain charset=UTF-8';
        add_header 'Content-Length' 0;

        return 204;
     }

     if ($request_method = 'POST') {

        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';

     }

     if ($request_method = 'GET') {

        add_header 'Access-Control-Allow-Origin' '*';
        add_header 'Access-Control-Allow-Credentials' 'true';
        add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type';

     }

}

add_header Access-Control-Allow-Origin $http_origin;
add_header Access-Control-Allow-Credentials true;

would work

Hi,

Is anyone able to assist with my issue. I am seeing that my cookie is coming through in the response headers, but not being saved on the browser. I am only noticing this in production (where I am using Nginx and SSL) and not in development (which is not using a proxy and not using SSL). I am using Express (Node) and Nginx on Ubuntu 18.04

My configurations are as follows:

Nginx (/etc/nginx/sites-available/default)

    server_name api.myBackendURL.net;

    location / {
    proxy_pass http://localhost:4000;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $host;
    proxy_cache_bypass $http_upgrade;
    proxy_set_header X-Forwarded-Proto $scheme;
    proxy_http_version 1.1;
   }

Cookie values, using express-session and cors

  const sessionOption: session.SessionOptions = {
    store: new RedisStore({
      client: redis
    }),
    name: 'qid',
    secret: 'njw32323ndiodqwnlad3',
    resave: false,
    proxy: process.env.NODE_ENV === 'production',
    saveUninitialized: false,
    cookie: {
      // Values from next examples with-passport
      domain: .myFrontendURL.app,
      maxAge: 1000 * 60 * 60 * 24 * 91, // 3 month cookie
      expires: new Date(Date.now() + 1000 * 60 * 60 * 24 * 365 * 1000),
      httpOnly: true,
      secure: process.env.NODE_ENV === 'production',
      path: '/',
      sameSite: 'lax'
    }
  }
  app.use(
    cors({
      origin: "https://subdomain.myFrontendURL.app",
      credentials: true
    })
  )

Headers in the Response

Access-Control-Allow-Credentials: true
Access-Control-Allow-Origin: https://subdomain.myFrontendURL.app,
Connection: keep-alive
Content-Length: 151
Content-Type: application/json; charset=utf-8
Date: Sat, 13 Jun 2020 10:18:28 GMT
ETag: W/"97-gYNuyhWohicUF549wSDDpEE4o3M"
Server: nginx/1.14.0 (Ubuntu)
Set-Cookie: qid=s%3AtP2fO9aX1Lo7uU_dLKOewqC9zxf8B-2P.vXSlE1khTK6Qe6O0lIn7g1WxJ1NIJyFHFoff8Jl1IO0; Path=/; HTTPOnly; Secure; Expires=Fri, 15 Oct 3019 09:47:00 GMT; HttpOnly; Secure; SameSite=Lax
Vary: Origin
X-Powered-By: Express

If it's of any use, the request headers are as follows:

accept: */*
Accept-Encoding: gzip, deflate, br
Accept-Language: en-GB,en-US;q=0.9,en;q=0.8
Connection: keep-alive
Content-Length: 282
content-type: application/json
Host: api.myBackendURL.net
Origin: https://subdomain.myFrontendURL.app
Referer: https://subdomain.myFrontendURL.app/
Sec-Fetch-Mode: cors
Sec-Fetch-Site: cross-site
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/78.0.3904.97 Safari/537.36

Just to note, sudo nginx -t returns test is successful, and I have restarted nginx etc.

So, i've never done anything with Nginx, cors, and have absolutely zero coding knowledge or experience, in a layman's terms, how in the world am i supposed to use any of this? It doesn't seem to work no matter how i do it. I'm using nginx 1.19.2

@DictatorL -- you'll find a file nginx/conf/nginx.conf in your installation that describes how nginx should accept traffic and route it to your application (here are some pre-canned ones you can use https://www.nginx.com/resources/wiki/start/#pre-canned-configurations). This gist shows you a few different examples of how you might setup CORS by using the add_header options, the exact one for you will depend on what you're trying to accomplish, you can learn more at https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS... although as I pointed out above using a wildcard for the origin is not correct, use this instead:

add_header "Access-Control-Allow-Origin" $http_origin;

@DictatorL -- you'll find a file nginx/conf/nginx.conf in your installation that describes how nginx should accept traffic and route it to your application (here are some pre-canned ones you can use https://www.nginx.com/resources/wiki/start/#pre-canned-configurations). This gist shows you a few different examples of how you might setup CORS by using the add_header options, the exact one for you will depend on what you're trying to accomplish, you can learn more at https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS... although as I pointed out above using a wildcard for the origin is not correct, use this instead:

add_header "Access-Control-Allow-Origin" $http_origin;

That worked!

Saved my days. I use:

add_header "Access-Control-Allow-Origin" $http_origin;
add_header 'Access-Control-Allow-Credentials' 'true';
add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, PUT';

For firefox, i installed this plugin
https://add0n.com/access-control.html?version=0.1.9&type=install

After the nginx config above, I was still getting cors erros.
Just installed this plugin and it works

not working for me, I always get 304 redirects on backend requests

@GromNaN thanks a lot :D
If you use a cache server, you must add a Vary: Origin to the response.

add_header "Access-Control-Allow-Origin" $http_origin;
add_header "Vary" "Origin";

It worked for allhost.my-domain.com

I try this configuration, but it is not working. I have a backend server with my code (laravel app) Do I need to have some configurations?