made port default depending on db engine

cloud/amazon/rds.py

@@ -112,9 +112,11 @@ options:
     default: null
   port:
     description:
-      - Port number that the DB instance uses for connections.  Defaults to 3306 for mysql. Must be changed to 1521 for Oracle, 1433 for SQL Server, 5432 for PostgreSQL. Used only when command=create or command=replicate.
+      - Port number that the DB instance uses for connections. Used only when command=create or command=replicate.
+      - Prior to 2.0 it always defaults to null and the API would use 3306, it had to be set to other DB default values when not using MySql.
+        Starting at 2.0 it auotmaticaly defaults to what is expected for each c(db_engine).
     required: false
-    default: null
+    default: 3306 for mysql, 1521 for Oracle, 1433 for SQL Server, 5432 for PostgreSQL.
   upgrade:
     description:
       - Indicates that minor version upgrades should be applied automatically. Used only when command=create or command=replicate.
@@ -289,6 +291,12 @@ try:
 except ImportError:
     has_rds2 = False
 
+DEFAULT_PORTS= {
+    'mysql': 3306,
+    'oracle': 1521,
+    'sqlserver': 1433,
+    'postgres': 5432,
+}
 
 class RDSException(Exception):
     def __init__(self, exc):
@@ -1040,6 +1048,14 @@ def main():
     if not region:
         module.fail_json(msg="Region not specified. Unable to determine region from EC2_REGION.")
 
+    # set port to per db defaults if not specified
+    if module.params['port'] is None and module.params['command'] in ['create', 'replicate']:
+        if '-' in module.params['db_engine']:
+            engine = module.params['db_engine'].split('-')[0]
+        else:
+            engine = module.params['db_engine']
+        module.params['port'] = DEFAULT_PORTS[engine.lower()]
+
     # connect to the rds endpoint
     if has_rds2:
         conn = RDS2Connection(module, region, **aws_connect_params)