SW-816: use default dbcreds from disk if none given

SAS/ResourceAssignment/ResourceAssignmentDatabase/radb.py

@@ -35,9 +35,14 @@ class RADBError(Exception):
     pass
 
 class RADatabase(PostgresDatabaseConnection):
-    def __init__(self, dbcreds: dbcredentials.DBCredentials,
+    def __init__(self, dbcreds: dbcredentials.DBCredentials=None,
                  num_connect_retries: int=5,
                  connect_retry_interval: float=1.0):
+
+        if dbcreds is None:
+            dbcreds = dbcredentials.DBCredentials().get("RADB")
+            logger.info("Read default RADB dbcreds from disk: %s" % dbcreds.stringWithHiddenPassword())
+
         super().__init__(dbcreds=dbcreds,
                          auto_commit_selects=False,
                          num_connect_retries=num_connect_retries,