How to enable CORS in Nginx proxy?

Question

Like my header, here is the configuration file located in conf.d / api-server.conf

server {
  listen 80;
  server_name api.localhost;

  location / {
    add_header 'Access-Control-Allow-Origin' 'http://api.localhost';
    add_header 'Access-Control-Allow_Credentials' 'true';
    add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
    add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH';

    if ($request_method = 'OPTIONS') {
      add_header 'Access-Control-Max-Age' 1728000;
      add_header 'Content-Type' 'text/plain charset=UTF-8';
      add_header 'Content-Length' 0;
      return 204;
    }

    proxy_redirect off;
    proxy_set_header host $host;
    proxy_set_header X-real-ip $remote_addr;
    proxy_set_header X-forward-for $proxy_add_x_forwarded_for;
    proxy_pass http://127.0.0.1:3000;
  }
}

The nginx.conf file remains the same as the default.

After I sent a request to api.localhost (api.localhost / admin / login), I still get 405 error:

XMLHttpRequest cannot load http://api.localhost/admin/login. Response 
to preflight request doesn't pass access control check: No 'Access-
Control-Allow-Origin' header is present on the requested resource. 
Origin 'http://admin.localhost:3000' is therefore not allowed access. 
The response had HTTP status code 405.

Answer 1

The problem is that your if condition does not send headers to the parent element in /. If you check the response headers before the flight, it will be

HTTP/1.1 204 No Content
Server: nginx/1.13.3
Date: Fri, 01 Sep 2017 05:24:04 GMT
Connection: keep-alive
Access-Control-Max-Age: 1728000
Content-Type: text/plain charset=UTF-8
Content-Length: 0

And it does not give anything. So there are two possible fixes for you. Copy add_headerinside if block also

server {
  listen 80;
  server_name api.localhost;

  location / {
    add_header 'Access-Control-Allow-Origin' 'http://api.localhost';
    add_header 'Access-Control-Allow_Credentials' 'true';
    add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
    add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH';

    if ($request_method = 'OPTIONS') {
      add_header 'Access-Control-Allow-Origin' 'http://api.localhost';
      add_header 'Access-Control-Allow_Credentials' 'true';
      add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
      add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH';
      add_header 'Access-Control-Max-Age' 1728000;
      add_header 'Content-Type' 'text/plain charset=UTF-8';
      add_header 'Content-Length' 0;
      return 204;
    }

    proxy_redirect off;
    proxy_set_header host $host;
    proxy_set_header X-real-ip $remote_addr;
    proxy_set_header X-forward-for $proxy_add_x_forwarded_for;
    proxy_pass http://127.0.0.1:3000;
  }
}

,

server {
   listen 80;
   server_name api.localhost;

 add_header 'Access-Control-Allow-Origin' 'http://api.localhost';
 add_header 'Access-Control-Allow_Credentials' 'true';
 add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
 add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH';

  location / {

    if ($request_method = 'OPTIONS') {
      add_header 'Access-Control-Max-Age' 1728000;
      add_header 'Content-Type' 'text/plain charset=UTF-8';
      add_header 'Content-Length' 0;
      return 204;
    }

    proxy_redirect off;
    proxy_set_header host $host;
    proxy_set_header X-real-ip $remote_addr;
    proxy_set_header X-forward-for $proxy_add_x_forwarded_for;
    proxy_pass http://127.0.0.1:3000;
  }
}

CORS. /api, conf

 add_header 'Access-Control-Allow-Origin' 'http://api.localhost';
 add_header 'Access-Control-Allow_Credentials' 'true';
 add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,Origin,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
 add_header 'Access-Control-Allow-Methods' 'GET,POST,OPTIONS,PUT,DELETE,PATCH';

include conf.d/corsheaders.conf;

OPTIONS /api. , CORS /api. , CORS, .

Answer 2

, :

The value of the 'Access-Control-Allow-Credentials' header in the response is '' which must be 'true' when the request credentials mode is 'include'

:

add_header 'Access-Control-Allow_Credentials' 'true';

:

add_header 'Access-Control-Allow-Credentials' 'true';