Wide-open CORS config for nginx

cors-nginx.conf

#
# Wide-open CORS config for nginx
#
location / {
   include proxy_params;
   proxy_pass http://127.0.0.1:5000;
   proxy_http_version  1.1;
   proxy_cache_bypass  $http_upgrade;
   proxy_set_header Upgrade           $http_upgrade;
   proxy_set_header Connection        "upgrade";
   proxy_set_header Host              $host;
   proxy_set_header X-Real-IP         $remote_addr;
   proxy_set_header X-Forwarded-For   $proxy_add_x_forwarded_for;
   proxy_set_header X-Forwarded-Proto $scheme;
   proxy_set_header X-Forwarded-Host  $host;
   proxy_set_header X-Forwarded-Port  $server_port;

   if ($request_method = 'OPTIONS') {
      add_header 'Access-Control-Allow-Origin' '*';
      add_header 'Access-Control-Allow-Credentials' 'true';
      add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS';
      add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Xauthtoken';
      add_header 'Access-Control-Max-Age' 1728000;
      add_header 'Content-Type' 'text/plain charset=UTF-8';
      add_header 'Content-Length'  0;
      return 200;
   }
   if ($request_method = 'POST') {
      add_header 'Access-Control-Allow-Origin' '*' always;
      add_header 'Access-Control-Allow-Credentials' 'true' always;
      add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
      add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Xauthtoken' $
      add_header 'Access-Control-Max-Age' 1728000 always;
#                add_header 'Content-Type' 'text/plain charset=UTF-8';

   }
   if ($request_method = 'GET') {
      add_header 'Access-Control-Allow-Origin' '*' always;
      add_header 'Access-Control-Allow-Credentials' 'true' always;
      add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
      add_header 'Access-Control-Allow-Headers' 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Xauthtoken' always;
   }
}