feat(database): verify that required database parameters

defaults/main.yml

@@ -20,7 +20,6 @@ drone_postgres_data_dir: "/var/lib/postgresql/data"
 drone_postgres_password: "drone"
 drone_postgres_user: "drone"
 drone_postgres_db: "drone"
-drone_database_datasource: ""
 drone_mysql_data_dir: "/var/lib/mysql/data"
 drone_mysql_password: "drone"
 drone_mysql_user: "drone"

tasks/drone-server.yml

@@ -1,4 +1,13 @@
 ---
+- name: verify that required database parameters
+  fail:
+    msg: "Variable '{{ item }}' is not defined for drone server setup"
+  when: item not in vars and drone_database_driver != "sqlite"
+  with_items:
+     - drone_database_datasource
+  tags:
+    - configuration
+
 - name: copy config for drone server
   template:
     src: "drone-server.env.j2"