Check connections before launching

* qc_app/__init__.py (refactor): Check connection before launching the
  application
* qc_app/check_connections.py (new file): Add code to check
  connections
* qc_app/db_utils.py (refactor): enable passing the database uri as an
  argument to the connection creation function.
* scripts/worker.py (refactor): Use new code to check for redis
  connection.

1 files changed, 5 insertions, 5 deletions

diff --git a/qc_app/db_utils.py b/qc_app/db_utils.py
index 95b0057..239f45c 100644
--- a/qc_app/db_utils.py
+++ b/qc_app/db_utils.py
@@ -1,20 +1,20 @@
 """module contains all db related stuff"""
-from typing import Tuple
+from typing import Tuple, Optional
 
 from urllib.parse import urlparse
 import MySQLdb as mdb
 from flask import current_app as app
 
-def parse_db_url() -> Tuple:
+def parse_db_url(db_url) -> Tuple:
     """
     Parse SQL_URI configuration variable.
     """
-    parsed_db = urlparse(app.config["SQL_URI"])
+    parsed_db = urlparse(db_url)
     return (parsed_db.hostname, parsed_db.username,
             parsed_db.password, parsed_db.path[1:])
 
 
-def database_connection() -> mdb.Connection:
+def database_connection(db_url: Optional[str] = None) -> mdb.Connection:
     """function to create db connector"""
-    host, user, passwd, db_name = parse_db_url()
+    host, user, passwd, db_name = parse_db_url(db_url or app.config["SQL_URI"])
     return mdb.connect(host, user, passwd, db_name)