Support for ecs describe_task_definition (#777)

* describe_task_definition support

* Refactor fetch_task_definition

* Add ECS Descriptors  (#772)

* Add support for "DescribeServices" in ecs mock

* Add support for "DescribeTaskDefinition" in ecs

* Let ecs responses handle baseobject for services

* Update Cloudformation/parsing#load_parameters to split commadelimitedlists into lists (#774)

* Fix JSON dump error in ecs.update_service with task_definition (#775)

* Fix s3bucketpath handling for IP based requests (#765)

* check HTTP header for IPv4 or IPv6 addresses and default to path based S3

* improved IPv4 and IPv6 checking with optional ports

* typo

* Freezetime.

* Add S3 ACL for aws-exec-read. Closes #740.

* Fixed time formatting in ec2/models.py (#778)

* Fixed time formatting in ec2/models.py

* Used freezegun on test that was failing due to time progression causing timestamp differences.

* rename duplicate rds/models db_instance_identifier to physical_resource_id (#776)

* rename duplicate db_instance_identifier to physical_resource_id

* Update create_from_cloudformation_json to use db_source_identifier str

* Update code to be more conventional.

* describe_task_definition support

* Refactor fetch_task_definition

moto/ecs/models.py

@@ -150,7 +150,7 @@ class EC2ContainerServiceBackend(BaseBackend):
         self.services = {}
         self.container_instances = {}
 
-    def fetch_task_definition(self, task_definition_str):
+    def describe_task_definition(self, task_definition_str):
         task_definition_components = task_definition_str.split(':')
         if len(task_definition_components) == 2:
             family, revision = task_definition_components
@@ -246,7 +246,7 @@ class EC2ContainerServiceBackend(BaseBackend):
             cluster = self.clusters[cluster_name]
         else:
             raise Exception("{0} is not a cluster".format(cluster_name))
-        task_definition = self.fetch_task_definition(task_definition_str)
+        task_definition = self.describe_task_definition(task_definition_str)
         if cluster_name not in self.tasks:
             self.tasks[cluster_name] = {}
         tasks = []
@@ -268,7 +268,7 @@ class EC2ContainerServiceBackend(BaseBackend):
             cluster = self.clusters[cluster_name]
         else:
             raise Exception("{0} is not a cluster".format(cluster_name))
-        task_definition = self.fetch_task_definition(task_definition_str)
+        task_definition = self.describe_task_definition(task_definition_str)
         if cluster_name not in self.tasks:
             self.tasks[cluster_name] = {}
         tasks = []
@@ -346,7 +346,7 @@ class EC2ContainerServiceBackend(BaseBackend):
             cluster = self.clusters[cluster_name]
         else:
             raise Exception("{0} is not a cluster".format(cluster_name))
-        task_definition = self.fetch_task_definition(task_definition_str)
+        task_definition = self.describe_task_definition(task_definition_str)
         desired_count = desired_count if desired_count is not None else 0
         service = Service(cluster, service_name, task_definition, desired_count)
         cluster_service_pair = '{0}:{1}'.format(cluster_name, service_name)
@@ -375,7 +375,7 @@ class EC2ContainerServiceBackend(BaseBackend):
         cluster_service_pair = '{0}:{1}'.format(cluster_name, service_name)
         if cluster_service_pair in self.services:
             if task_definition_str is not None:
-                self.fetch_task_definition(task_definition_str)
+                task_definition = self.describe_task_definition(task_definition_str)
                 self.services[cluster_service_pair].task_definition = task_definition_str
             if desired_count is not None:
                 self.services[cluster_service_pair].desired_count = desired_count

moto/ecs/responses.py

@@ -105,6 +105,14 @@ class EC2ContainerServiceResponse(BaseResponse):
             'failures': []
         })
 
+    def describe_task_definition(self):
+        task_definition_str = self._get_param('taskDefinition')
+        data = self.ecs_backend.describe_task_definition(task_definition_str)
+        return json.dumps({
+            'taskDefinition': data.response_object,
+            'failures': []
+        })
+
     def start_task(self):
         cluster_str = self._get_param('cluster')
         overrides = self._get_param('overrides')

tests/test_ecs/test_ecs_boto3.py

@@ -832,6 +832,31 @@ def test_describe_tasks():
     set([response['tasks'][0]['taskArn'], response['tasks'][1]['taskArn']]).should.equal(set(tasks_arns))
 
 
+@mock_ecs
+def describe_task_definition():
+    client = boto3.client('ecs', region_name='us-east-1')
+    container_definition = {
+        'name': 'hello_world',
+        'image': 'docker/hello-world:latest',
+        'cpu': 1024,
+        'memory': 400,
+        'essential': True,
+        'environment': [{
+            'name': 'AWS_ACCESS_KEY_ID',
+            'value': 'SOME_ACCESS_KEY'
+        }],
+        'logConfiguration': {'logDriver': 'json-file'}
+    }
+    task_definition = client.register_task_definition(
+        family='test_ecs_task',
+        containerDefinitions=[container_definition]
+    )
+    family = task_definition['family']
+    task = client.describe_task_definition(taskDefinition=family)
+    task['containerDefinitions'][0].should.equal(container_definition)
+    task['taskDefinitionArn'].should.equal('arn:aws:ecs:us-east-1:012345678910:task-definition/test_ecs_task2:1')
+    task['volumes'].should.equal([])
+
 @mock_ec2
 @mock_ecs
 def test_stop_task():