gitlab: Ajax will send OPTIONS request which is not implemented in gitlab, ngix can reply

When getting a raw file in gitlab with ajax a first OPTIONS request is send, this simply fail because not implemented. To solve the problem, we allow nginx to reply to OPTIONS request and allow GET method.

/reviewed-on nexedi/slapos!663

software/gitlab/buildout.hash.cfg

@@ -66,7 +66,7 @@ md5sum = a56a44e96f65f5ed20211bb6a54279f4
 
 [nginx-gitlab-http.conf.in]
 _update_hash_filename_ = template/nginx-gitlab-http.conf.in
-md5sum = abcc5eda03e10b26c74619f299a7f6a8
+md5sum  = e74695aa1be60f0ffac64ddbe1c8eaf1
 
 [nginx.conf.in]
 _update_hash_filename_ = template/nginx.conf.in

software/gitlab/template/nginx-gitlab-http.conf.in

@@ -121,6 +121,13 @@ server {
     # Set CORS header
     add_header 'Access-Control-Allow-Origin' {{ cfg('nginx_header_allow_origin') }};
     add_header 'Access-Control-Allow-Credentials' true;
+    if ($request_method = OPTIONS ) {
+        add_header Allow "GET, OPTIONS";
+        add_header Content-Type text/plain;
+        add_header 'Access-Control-Allow-Origin' $http_origin;
+        add_header Access-Control-Allow-Headers "Origin, X-Requested-With, Authorization, Content-Type, Accept";
+        return 200;
+    }
     ## If you use HTTPS make sure you disable gzip compression
     ## to be safe against BREACH attack.
     {{ 'gzip off;' if cfg_https else ''}}