preseed values from config file

debian/config

@@ -1,11 +1,23 @@
 #!/bin/sh
 # config maintainer script for gitlab
+
+CONFIGFILE=/etc/gitlab/gitlab-debian.conf
  
 set -e
 
 # source debconf stuffs
 . /usr/share/debconf/confmodule
 
+# Load config file, if it exists.
+  if [ -e $CONFIGFILE ]; then
+      . $CONFIGFILE || true
+
+      # Store values from config file into
+      # debconf db.
+      db_set gitlab/fqdn "$GITLAB_HOST"
+      db_set gitlab/user "$gitlab_user"
+  fi
+
 # What is your fqdn?
 db_input high gitlab/fqdn || true
 db_go