obtain noblogs master from config file

bin/generate-noblogsmv-map

@@ -12,7 +12,8 @@ USAGE
 //
 // Stampa una mappa delle assegnazioni blog -> backend, per NGINX.
 // IP interno del master.
-define('NOBLOGS_MASTER', '172.16.1.10');
+$master_url = file_get_contents('/etc/noblogs.master');
+$noblogs_master = parse_url($master_url)['host'];
 
 
 #
@@ -124,7 +125,7 @@ function printline($s) {
 function backend_to_http_endpoint($backend) {
   if (substr($backend, 0, 8) != 'backend_') {
     error_log('diamine, di questo backend non so che farmene: ' . $backend);
-    return NOBLOGS_MASTER . ':82';
+    return $noblogs_master . ':82';
   }
   $id = substr($backend, 8);
   return '172.16.1.' . $id . ':82';
@@ -138,7 +139,7 @@ function generate_map() {
   $blogs = get_blogs();
 
   printline('map $http_host $backend_noblogs {');
-  printline(' default http://' . NOBLOGS_MASTER . ':82;');
+  printline(' default http://' . $noblogs_master . ':82;');
   foreach ($blogs as $blog) {
     $blog_id = $blog->blog_id;
     if ($blog_id == 1)