change API key settings

nginx/conf.d/default.conf.template

@@ -1,6 +1,7 @@
 # ---------------------------  ENV-Key übernehmen  ---------------------------
 # envsubst ersetzt ${MEDIA_API_KEY} durch den Wert aus docker-compose.yml
 set $secret_key "${MEDIA_API_KEY}";
+set $server_url "${SERVER_NAME}";
 
 map $request_method $cors_preflight {
     "OPTIONS" 1;
@@ -9,7 +10,7 @@ map $request_method $cors_preflight {
 
 server {
     listen 80;
-    server_name localhost;
+    server_name $server_url;
 
     root /usr/share/nginx/html;
     index index.html;