Add Fargate support for ECS modules

Fargate instances do not require memory and cpu descriptors. EC2 instances
 do require descriptions. https://botocore.readthedocs.io/en/latest/reference/services/ecs.html#ECS.Client.describe_task_definition

Fargate requires that cpu and memory be defined at task definition level.
EC2 launch requires them to be defined at the container level.

Fargate requires the use of awsvpc for the networking_mode. Also updated,
the documentation regarding where and when memory/cpu needs to the assigned.

The task_definition variable for the awspvc configuration colided with
the ecs_service for the bridge network. This would cause the test to fail.

Add testing for fargate

Add examples for fargate and ec2

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

@@ -107,9 +107,8 @@ options:
         description:
           - The launch type on which to run your service
         required: false
-        version_added: 2.5
+        version_added: 2.7
         choices: ["EC2", "FARGATE"]
-        default: "EC2"
 extends_documentation_fragment:
     - aws
     - ec2
@@ -376,10 +375,12 @@ class EcsServiceManager:
             role=role,
             deploymentConfiguration=deployment_configuration,
             placementConstraints=placement_constraints,
-            placementStrategy=placement_strategy,
-            launchType=launch_type)
+            placementStrategy=placement_strategy
+        )
         if network_configuration:
             params['networkConfiguration'] = network_configuration
+        if launch_type:
+            params['launchType'] = launch_type
         response = self.ecs.create_service(**params)
         return self.jsonize(response['service'])
 
@@ -441,12 +442,13 @@ def main():
         placement_constraints=dict(required=False, default=[], type='list'),
         placement_strategy=dict(required=False, default=[], type='list'),
         network_configuration=dict(required=False, type='dict'),
-        launch_type=dict(required=False, choices=['EC2', 'FARGATE'], default='EC2')
+        launch_type=dict(required=False, choices=['EC2', 'FARGATE'])
     ))
 
     module = AnsibleAWSModule(argument_spec=argument_spec,
                               supports_check_mode=True,
-                              required_if=[('state', 'present', ['task_definition', 'desired_count'])],
+                              required_if=[('state', 'present', ['task_definition', 'desired_count']),
+                                           ('launch_type', 'FARGATE', ['network_configuration'])],
                               required_together=[['load_balancers', 'role']])
 
     service_mgr = EcsServiceManager(module)
@@ -468,10 +470,16 @@ def main():
         module.fail_json(msg="Exception describing service '" + module.params['name'] + "' in cluster '" + module.params['cluster'] + "': " + str(e))
 
     results = dict(changed=False)
+
+    if module.params['launch_type']:
+        if not module.botocore_at_least('1.8.4'):
+            module.fail_json(msg='botocore needs to be version 1.8.4 or higher to use launch_type')
+
     if module.params['state'] == 'present':
 
         matching = False
         update = False
+
         if existing and 'status' in existing and existing['status'] == "ACTIVE":
             if service_mgr.is_matching_service(module.params, existing):
                 matching = True
@@ -501,18 +509,21 @@ def main():
                         if 'containerPort' in loadBalancer:
                             loadBalancer['containerPort'] = int(loadBalancer['containerPort'])
                     # doesn't exist. create it.
-                    response = service_mgr.create_service(module.params['name'],
-                                                          module.params['cluster'],
-                                                          module.params['task_definition'],
-                                                          loadBalancers,
-                                                          module.params['desired_count'],
-                                                          clientToken,
-                                                          role,
-                                                          deploymentConfiguration,
-                                                          module.params['placement_constraints'],
-                                                          module.params['placement_strategy'],
-                                                          network_configuration,
-                                                          module.params['launch_type'])
+                    try:
+                        response = service_mgr.create_service(module.params['name'],
+                                                              module.params['cluster'],
+                                                              module.params['task_definition'],
+                                                              loadBalancers,
+                                                              module.params['desired_count'],
+                                                              clientToken,
+                                                              role,
+                                                              deploymentConfiguration,
+                                                              module.params['placement_constraints'],
+                                                              module.params['placement_strategy'],
+                                                              network_configuration,
+                                                              module.params['launch_type'])
+                    except botocore.exceptions.ClientError as e:
+                        module.fail_json(msg=e.message)
 
                 results['service'] = response