HOT-FIX: conserta CORS' preflight steps in browser

docker/config/nginx/sapl.conf

@@ -13,6 +13,22 @@ server {
 
     location /api/ {
         add_header 'Access-Control-Allow-Origin' '*';
+        add_header 'Access-Control-Allow-Credentials' 'true';
+        add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, HEAD, OPTIONS';
+        add_header 'Access-Control-Allow-Headers' 'Access-Control-Allow-Origin,XMLHttpRequest,Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Mx-ReqToken,X-Requested-With';
+        add_header 'Access-Control-Expose-Headers' 'Access-Control-Allow-Origin,XMLHttpRequest,Accept,Authorization,Cache-Control,Content-Type,DNT,If-Modified-Since,Keep-Alive,Origin,User-Agent,X-Mx-ReqToken,X-Requested-With';
+
+#      handle the browser's preflight steps
+       if ($request_method = 'OPTIONS') {
+             add_header 'Access-Control-Allow-Origin' '*';
+             add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, DELETE, HEAD, OPTIONS';
+             add_header 'Access-Control-Allow-Headers' 'Authorization,Accept,DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
+             add_header 'Access-Control-Expose-Headers' 'DNT,X-CustomHeader,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Content-Range,Range';
+             add_header 'Access-Control-Max-Age' 1728000;
+             add_header 'Content-Type' 'text/plain; charset=utf-8';
+             add_header 'Content-Length' 0;
+             return 204;
+        }
 
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
         proxy_set_header Host $http_host;