Route custom waiter (#36922)

This creates a way for us to use boto3's data-driven waiter support to use custom waiters where Boto3 hasn't implemented them yet.

The only waiter implemented so far is for VPC Route Tables to check that they exist, and this replaces some custom retry code.

lib/ansible/module_utils/aws/waiters.py

@@ -0,0 +1,52 @@
+# Copyright: (c) 2018, Ansible Project
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+try:
+    import botocore.waiter as core_waiter
+except ImportError:
+    pass  # caught by HAS_BOTO3
+
+
+ec2_data = {
+    "version": 2,
+    "waiters": {
+        "RouteTableExists": {
+            "delay": 5,
+            "maxAttempts": 40,
+            "operation": "DescribeRouteTables",
+            "acceptors": [
+                {
+                    "matcher": "path",
+                    "expected": True,
+                    "argument": "length(RouteTables[]) > `0`",
+                    "state": "success"
+                },
+                {
+                    "matcher": "error",
+                    "expected": "InvalidRouteTableID.NotFound",
+                    "state": "retry"
+                }
+            ]
+        }
+    }
+}
+
+
+def model_for(name):
+    ec2_models = core_waiter.WaiterModel(waiter_config=ec2_data)
+    return ec2_models.get_waiter(name)
+
+
+waiters_by_name = {
+    ('EC2', 'route_table_exists'): lambda ec2: core_waiter.Waiter(
+        'route_table_exists',
+        model_for('RouteTableExists'),
+        ec2.describe_route_tables)
+}
+
+
+def get_waiter(client, waiter_name):
+    try:
+        return waiters_by_name[(client.__class__.__name__, waiter_name)](client)
+    except KeyError:
+        raise NotImplementedError("Waiter {0} could not be found for client {1}. Available waiters: {2}".format(
+            waiter_name, type(client), ', '.join(repr(k) for k in waiters_by_name.keys())))

lib/ansible/modules/cloud/amazon/ec2_vpc_route_table.py

@@ -226,6 +226,7 @@ route_table:
 import re
 from time import sleep
 from ansible.module_utils.aws.core import AnsibleAWSModule
+from ansible.module_utils.aws.waiters import get_waiter
 from ansible.module_utils.ec2 import ec2_argument_spec, boto3_conn, get_aws_connection_info
 from ansible.module_utils.ec2 import ansible_dict_to_boto3_filter_list
 from ansible.module_utils.ec2 import camel_dict_to_snake_dict, snake_dict_to_camel_dict
@@ -649,11 +650,11 @@ def ensure_route_table_present(connection, module):
             try:
                 route_table = connection.create_route_table(VpcId=vpc_id)['RouteTable']
                 # try to wait for route table to be present before moving on
-                for attempt in range(5):
-                    if not get_route_table_by_id(connection, module, route_table['RouteTableId']):
-                        sleep(2)
-                    else:
-                        break
+                get_waiter(
+                    connection, 'route_table_exists'
+                ).wait(
+                    RouteTableIds=[route_table['RouteTableId']],
+                )
             except (botocore.exceptions.ClientError, botocore.exceptions.BotoCoreError) as e:
                 module.fail_json_aws(e, msg="Error creating route table")
         else: