read values from config file to debconf db

debian/diaspora-common.config

 #!/bin/sh
-# config maintainer script for diaspora-installer
+# config maintainer script for diaspora-common
+
+CONFIGFILE=/etc/diaspora.conf
  
 set -e
 
+
 # source debconf stuff
 . /usr/share/debconf/confmodule
 
+# Load config file, if it exists.
+  if [ -e $CONFIGFILE ]; then
+      . $CONFIGFILE || true
+
+      # Store values from config file into
+      # debconf db.
+      db_set diaspora-common/url "$SERVERNAME"
+      db_set diaspora-common/ssl "$diaspora_https:-true"
+      db_set diaspora-common/letsencrypt "${diaspora_letsencrypt:-false}"
+  fi
+
 # What is your pod address?
 db_input high diaspora-common/url || true
 db_go