Postgres: fix detection of existing roles

Role "root" it is hardcode.
In general case role name comes from  local.conf: string  "DATABASE_USER="

Change-Id: Iedfca48e04d23c313851f48d68ac40ba29340805
diff --git a/lib/databases/postgresql b/lib/databases/postgresql
index 14425a5..1f347f5 100644
--- a/lib/databases/postgresql
+++ b/lib/databases/postgresql
@@ -47,7 +47,7 @@
 }
 
 function configure_database_postgresql {
-    local pg_conf pg_dir pg_hba root_roles version
+    local pg_conf pg_dir pg_hba check_role version
     echo_summary "Configuring and starting PostgreSQL"
     if is_fedora; then
         pg_hba=/var/lib/pgsql/data/pg_hba.conf
@@ -85,8 +85,8 @@
     restart_service postgresql
 
     # Create the role if it's not here or else alter it.
-    root_roles=$(sudo -u root sudo -u postgres -i psql -t -c "SELECT 'HERE' from pg_roles where rolname='root'")
-    if [[ ${root_roles} == *HERE ]];then
+    check_role=$(sudo -u root sudo -u postgres -i psql -t -c "SELECT 'HERE' from pg_roles where rolname='$DATABASE_USER'")
+    if [[ ${check_role} == *HERE ]];then
         sudo -u root sudo -u postgres -i psql -c "ALTER ROLE $DATABASE_USER WITH SUPERUSER LOGIN PASSWORD '$DATABASE_PASSWORD'"
     else
         sudo -u root sudo -u postgres -i psql -c "CREATE ROLE $DATABASE_USER WITH SUPERUSER LOGIN PASSWORD '$DATABASE_PASSWORD'"