Check mode fixes for ec2_vpc_net module (#2179)

* Check mode fixes for ec2_vpc_net module

Returns VPC object information

Detects state change for VPC, DHCP options, and tags in check mode

* Early exit on VPC creation in check mode

lib/ansible/modules/cloud/amazon/ec2_vpc_net.py

@@ -144,6 +144,7 @@ def update_vpc_tags(vpc, module, vpc_obj, tags, name):
     try:
         current_tags = dict((t.name, t.value) for t in vpc.get_all_tags(filters={'resource-id': vpc_obj.id}))
         if cmp(tags, current_tags):
+            if not module.check_mode:
                 vpc.create_tags(vpc_obj.id, tags)
             return True
         else:
@@ -156,6 +157,7 @@ def update_vpc_tags(vpc, module, vpc_obj, tags, name):
 def update_dhcp_opts(connection, module, vpc_obj, dhcp_id):
 
     if vpc_obj.dhcp_options_id != dhcp_id:
+        if not module.check_mode:
             connection.associate_dhcp_options(dhcp_id, vpc_obj.id)
         return True
     else:
@@ -192,6 +194,7 @@ def main():
 
     module = AnsibleModule(
         argument_spec=argument_spec,
+        supports_check_mode=True
     )
 
     if not HAS_BOTO:
@@ -229,8 +232,11 @@ def main():
 
         if vpc_obj is None:
             try:
-                vpc_obj = connection.create_vpc(cidr_block, instance_tenancy=tenancy)
                 changed = True
+                if not module.check_mode:
+                    vpc_obj = connection.create_vpc(cidr_block, instance_tenancy=tenancy)
+                else:
+                    module.exit_json(changed=changed)
             except BotoServerError as e:
                 module.fail_json(msg=e)
 
@@ -252,12 +258,14 @@ def main():
         # which is needed in order to detect the current status of DNS options. For now we just update
         # the attribute each time and is not used as a changed-factor.
         try:
+            if not module.check_mode:
                 connection.modify_vpc_attribute(vpc_obj.id, enable_dns_support=dns_support)
                 connection.modify_vpc_attribute(vpc_obj.id, enable_dns_hostnames=dns_hostnames)
         except BotoServerError as e:
             e_msg=boto_exception(e)
             module.fail_json(msg=e_msg)
 
+        if not module.check_mode:
             # get the vpc obj again in case it has changed
             try:
                 vpc_obj = connection.get_all_vpcs(vpc_obj.id)[0]
@@ -274,6 +282,7 @@ def main():
 
         if vpc_obj is not None:
             try:
+                if not module.check_mode:
                     connection.delete_vpc(vpc_obj.id)
                 vpc_obj = None
                 changed = True