Application Autoscaling basic features (#3082)

* Placeholder to test Application Autoscaling.

* Wire everything together and create a first passing test without any real functionality.

* Get one test working properly.

* Add some TODO items.

* Reformat code with black

* Second passing test for describe_scalable_targets.

* New test for NextToken.

* Add some tests for ParamValidationError and ValidationException.

* black

* Ensure scalable targets are being captured in an OrderedDict() for deterministic return later.

* Add validation to describe_scalable_targets and register_scalable_target.

* Fix tests.

* Add creation_time, refactor, add ECS backend, and add failing test for checking that ecs service exists.

* Add parameter validation.

* Improved documentation for CONTRIBUTING.md

Adds some details to give people an idea what's involved in adding new features/services

* Integrate with ECS.

* black

* Refactor to allow implementation of SuspendedState.

* Complete support for SuspendedState.

* Bump up implementation coverage percentage.

* Tidy up code; add comments.

* Implement suggested changes from code review.

* Minor refactorings for elegance.

* README update

Co-authored-by: Bert Blommers <bblommers@users.noreply.github.com>

moto/__init__.py

@@ -15,6 +15,9 @@ mock_acm = lazy_load(".acm", "mock_acm")
 mock_apigateway = lazy_load(".apigateway", "mock_apigateway")
 mock_apigateway_deprecated = lazy_load(".apigateway", "mock_apigateway_deprecated")
 mock_athena = lazy_load(".athena", "mock_athena")
+mock_applicationautoscaling = lazy_load(
+    ".applicationautoscaling", "mock_applicationautoscaling"
+)
 mock_autoscaling = lazy_load(".autoscaling", "mock_autoscaling")
 mock_autoscaling_deprecated = lazy_load(".autoscaling", "mock_autoscaling_deprecated")
 mock_lambda = lazy_load(".awslambda", "mock_lambda")

moto/applicationautoscaling/__init__.py

@@ -0,0 +1,6 @@
+from __future__ import unicode_literals
+from .models import applicationautoscaling_backends
+from ..core.models import base_decorator
+
+applicationautoscaling_backend = applicationautoscaling_backends["us-east-1"]
+mock_applicationautoscaling = base_decorator(applicationautoscaling_backends)

moto/applicationautoscaling/exceptions.py

@@ -0,0 +1,22 @@
+from __future__ import unicode_literals
+import json
+
+
+class AWSError(Exception):
+    """ Copied from acm/models.py; this class now exists in >5 locations,
+        maybe this should be centralised for use by any module?
+    """
+
+    TYPE = None
+    STATUS = 400
+
+    def __init__(self, message):
+        self.message = message
+
+    def response(self):
+        resp = {"__type": self.TYPE, "message": self.message}
+        return json.dumps(resp), dict(status=self.STATUS)
+
+
+class AWSValidationException(AWSError):
+    TYPE = "ValidationException"

moto/applicationautoscaling/models.py

@@ -0,0 +1,179 @@
+from __future__ import unicode_literals
+from moto.core import BaseBackend, BaseModel
+from moto.ecs import ecs_backends
+from .exceptions import AWSValidationException
+from collections import OrderedDict
+from enum import Enum, unique
+import time
+
+
+@unique
+class ServiceNamespaceValueSet(Enum):
+    APPSTREAM = "appstream"
+    RDS = "rds"
+    LAMBDA = "lambda"
+    CASSANDRA = "cassandra"
+    DYNAMODB = "dynamodb"
+    CUSTOM_RESOURCE = "custom-resource"
+    ELASTICMAPREDUCE = "elasticmapreduce"
+    EC2 = "ec2"
+    COMPREHEND = "comprehend"
+    ECS = "ecs"
+    SAGEMAKER = "sagemaker"
+
+
+@unique
+class ScalableDimensionValueSet(Enum):
+    CASSANDRA_TABLE_READ_CAPACITY_UNITS = "cassandra:table:ReadCapacityUnits"
+    CASSANDRA_TABLE_WRITE_CAPACITY_UNITS = "cassandra:table:WriteCapacityUnits"
+    DYNAMODB_INDEX_READ_CAPACITY_UNITS = "dynamodb:index:ReadCapacityUnits"
+    DYNAMODB_INDEX_WRITE_CAPACITY_UNITS = "dynamodb:index:WriteCapacityUnits"
+    DYNAMODB_TABLE_READ_CAPACITY_UNITS = "dynamodb:table:ReadCapacityUnits"
+    DYNAMODB_TABLE_WRITE_CAPACITY_UNITS = "dynamodb:table:WriteCapacityUnits"
+    RDS_CLUSTER_READ_REPLICA_COUNT = "rds:cluster:ReadReplicaCount"
+    RDS_CLUSTER_CAPACITY = "rds:cluster:Capacity"
+    COMPREHEND_DOCUMENT_CLASSIFIER_ENDPOINT_DESIRED_INFERENCE_UNITS = (
+        "comprehend:document-classifier-endpoint:DesiredInferenceUnits"
+    )
+    ELASTICMAPREDUCE_INSTANCE_FLEET_ON_DEMAND_CAPACITY = (
+        "elasticmapreduce:instancefleet:OnDemandCapacity"
+    )
+    ELASTICMAPREDUCE_INSTANCE_FLEET_SPOT_CAPACITY = (
+        "elasticmapreduce:instancefleet:SpotCapacity"
+    )
+    ELASTICMAPREDUCE_INSTANCE_GROUP_INSTANCE_COUNT = (
+        "elasticmapreduce:instancegroup:InstanceCount"
+    )
+    LAMBDA_FUNCTION_PROVISIONED_CONCURRENCY = "lambda:function:ProvisionedConcurrency"
+    APPSTREAM_FLEET_DESIRED_CAPACITY = "appstream:fleet:DesiredCapacity"
+    CUSTOM_RESOURCE_RESOURCE_TYPE_PROPERTY = "custom-resource:ResourceType:Property"
+    SAGEMAKER_VARIANT_DESIRED_INSTANCE_COUNT = "sagemaker:variant:DesiredInstanceCount"
+    EC2_SPOT_FLEET_REQUEST_TARGET_CAPACITY = "ec2:spot-fleet-request:TargetCapacity"
+    ECS_SERVICE_DESIRED_COUNT = "ecs:service:DesiredCount"
+
+
+class ApplicationAutoscalingBackend(BaseBackend):
+    def __init__(self, region, ecs):
+        super(ApplicationAutoscalingBackend, self).__init__()
+        self.region = region
+        self.ecs_backend = ecs
+        self.targets = OrderedDict()
+
+    def reset(self):
+        region = self.region
+        ecs = self.ecs_backend
+        self.__dict__ = {}
+        self.__init__(region, ecs)
+
+    @property
+    def applicationautoscaling_backend(self):
+        return applicationautoscaling_backends[self.region]
+
+    def describe_scalable_targets(
+        self, namespace, r_ids=None, dimension=None,
+    ):
+        """ Describe scalable targets. """
+        if r_ids is None:
+            r_ids = []
+        targets = self._flatten_scalable_targets(namespace)
+        if dimension is not None:
+            targets = [t for t in targets if t.scalable_dimension == dimension]
+        if len(r_ids) > 0:
+            targets = [t for t in targets if t.resource_id in r_ids]
+        return targets
+
+    def _flatten_scalable_targets(self, namespace):
+        """ Flatten scalable targets for a given service namespace down to a list. """
+        targets = []
+        for dimension in self.targets.keys():
+            for resource_id in self.targets[dimension].keys():
+                targets.append(self.targets[dimension][resource_id])
+        targets = [t for t in targets if t.service_namespace == namespace]
+        return targets
+
+    def register_scalable_target(self, namespace, r_id, dimension, **kwargs):
+        """ Registers or updates a scalable target. """
+        _ = _target_params_are_valid(namespace, r_id, dimension)
+        if namespace == ServiceNamespaceValueSet.ECS.value:
+            _ = self._ecs_service_exists_for_target(r_id)
+        if self._scalable_target_exists(r_id, dimension):
+            target = self.targets[dimension][r_id]
+            target.update(kwargs)
+        else:
+            target = FakeScalableTarget(self, namespace, r_id, dimension, **kwargs)
+            self._add_scalable_target(target)
+        return target
+
+    def _scalable_target_exists(self, r_id, dimension):
+        return r_id in self.targets.get(dimension, [])
+
+    def _ecs_service_exists_for_target(self, r_id):
+        """ Raises a ValidationException if an ECS service does not exist
+            for the specified resource ID.
+        """
+        resource_type, cluster, service = r_id.split("/")
+        result = self.ecs_backend.describe_services(cluster, [service])
+        if len(result) != 1:
+            raise AWSValidationException("ECS service doesn't exist: {}".format(r_id))
+        return True
+
+    def _add_scalable_target(self, target):
+        if target.scalable_dimension not in self.targets:
+            self.targets[target.scalable_dimension] = OrderedDict()
+        if target.resource_id not in self.targets[target.scalable_dimension]:
+            self.targets[target.scalable_dimension][target.resource_id] = target
+        return target
+
+
+def _target_params_are_valid(namespace, r_id, dimension):
+    """ Check whether namespace, resource_id and dimension are valid and consistent with each other. """
+    is_valid = True
+    valid_namespaces = [n.value for n in ServiceNamespaceValueSet]
+    if namespace not in valid_namespaces:
+        is_valid = False
+    if dimension is not None:
+        try:
+            valid_dimensions = [d.value for d in ScalableDimensionValueSet]
+            d_namespace, d_resource_type, scaling_property = dimension.split(":")
+            resource_type, cluster, service = r_id.split("/")
+            if (
+                dimension not in valid_dimensions
+                or d_namespace != namespace
+                or resource_type != d_resource_type
+            ):
+                is_valid = False
+        except ValueError:
+            is_valid = False
+    if not is_valid:
+        raise AWSValidationException(
+            "Unsupported service namespace, resource type or scalable dimension"
+        )
+    return is_valid
+
+
+class FakeScalableTarget(BaseModel):
+    def __init__(
+        self, backend, service_namespace, resource_id, scalable_dimension, **kwargs
+    ):
+        self.applicationautoscaling_backend = backend
+        self.service_namespace = service_namespace
+        self.resource_id = resource_id
+        self.scalable_dimension = scalable_dimension
+        self.min_capacity = kwargs["min_capacity"]
+        self.max_capacity = kwargs["max_capacity"]
+        self.role_arn = kwargs["role_arn"]
+        self.suspended_state = kwargs["suspended_state"]
+        self.creation_time = time.time()
+
+    def update(self, **kwargs):
+        if kwargs["min_capacity"] is not None:
+            self.min_capacity = kwargs["min_capacity"]
+        if kwargs["max_capacity"] is not None:
+            self.max_capacity = kwargs["max_capacity"]
+
+
+applicationautoscaling_backends = {}
+for region_name, ecs_backend in ecs_backends.items():
+    applicationautoscaling_backends[region_name] = ApplicationAutoscalingBackend(
+        region_name, ecs_backend
+    )

moto/applicationautoscaling/responses.py

@@ -0,0 +1,97 @@
+from __future__ import unicode_literals
+from moto.core.responses import BaseResponse
+import json
+from .models import (
+    applicationautoscaling_backends,
+    ScalableDimensionValueSet,
+    ServiceNamespaceValueSet,
+)
+from .exceptions import AWSValidationException
+
+
+class ApplicationAutoScalingResponse(BaseResponse):
+    @property
+    def applicationautoscaling_backend(self):
+        return applicationautoscaling_backends[self.region]
+
+    def describe_scalable_targets(self):
+        try:
+            self._validate_params()
+        except AWSValidationException as e:
+            return e.response()
+        service_namespace = self._get_param("ServiceNamespace")
+        resource_ids = self._get_param("ResourceIds")
+        scalable_dimension = self._get_param("ScalableDimension")
+        max_results = self._get_int_param("MaxResults", 50)
+        marker = self._get_param("NextToken")
+        all_scalable_targets = self.applicationautoscaling_backend.describe_scalable_targets(
+            service_namespace, resource_ids, scalable_dimension
+        )
+        start = int(marker) + 1 if marker else 0
+        next_token = None
+        scalable_targets_resp = all_scalable_targets[start : start + max_results]
+        if len(all_scalable_targets) > start + max_results:
+            next_token = str(len(scalable_targets_resp) - 1)
+        targets = [_build_target(t) for t in scalable_targets_resp]
+        return json.dumps({"ScalableTargets": targets, "NextToken": next_token})
+
+    def register_scalable_target(self):
+        """ Registers or updates a scalable target. """
+        try:
+            self._validate_params()
+            self.applicationautoscaling_backend.register_scalable_target(
+                self._get_param("ServiceNamespace"),
+                self._get_param("ResourceId"),
+                self._get_param("ScalableDimension"),
+                min_capacity=self._get_int_param("MinCapacity"),
+                max_capacity=self._get_int_param("MaxCapacity"),
+                role_arn=self._get_param("RoleARN"),
+                suspended_state=self._get_param("SuspendedState"),
+            )
+        except AWSValidationException as e:
+            return e.response()
+        return json.dumps({})
+
+    def _validate_params(self):
+        """ Validate parameters.
+            TODO Integrate this validation with the validation in models.py
+        """
+        namespace = self._get_param("ServiceNamespace")
+        dimension = self._get_param("ScalableDimension")
+        messages = []
+        dimensions = [d.value for d in ScalableDimensionValueSet]
+        message = None
+        if dimension is not None and dimension not in dimensions:
+            messages.append(
+                "Value '{}' at 'scalableDimension' "
+                "failed to satisfy constraint: Member must satisfy enum value set: "
+                "{}".format(dimension, dimensions)
+            )
+        namespaces = [n.value for n in ServiceNamespaceValueSet]
+        if namespace is not None and namespace not in namespaces:
+            messages.append(
+                "Value '{}' at 'serviceNamespace' "
+                "failed to satisfy constraint: Member must satisfy enum value set: "
+                "{}".format(namespace, namespaces)
+            )
+        if len(messages) == 1:
+            message = "1 validation error detected: {}".format(messages[0])
+        elif len(messages) > 1:
+            message = "{} validation errors detected: {}".format(
+                len(messages), "; ".join(messages)
+            )
+        if message:
+            raise AWSValidationException(message)
+
+
+def _build_target(t):
+    return {
+        "CreationTime": t.creation_time,
+        "ServiceNamespace": t.service_namespace,
+        "ResourceId": t.resource_id,
+        "RoleARN": t.role_arn,
+        "ScalableDimension": t.scalable_dimension,
+        "MaxCapacity": t.max_capacity,
+        "MinCapacity": t.min_capacity,
+        "SuspendedState": t.suspended_state,
+    }

moto/applicationautoscaling/urls.py

@@ -0,0 +1,8 @@
+from __future__ import unicode_literals
+from .responses import ApplicationAutoScalingResponse
+
+url_bases = ["https?://application-autoscaling.(.+).amazonaws.com"]
+
+url_paths = {
+    "{0}/$": ApplicationAutoScalingResponse.dispatch,
+}

moto/applicationautoscaling/utils.py

@@ -0,0 +1,10 @@
+from six.moves.urllib.parse import urlparse
+
+
+def region_from_applicationautoscaling_url(url):
+    domain = urlparse(url).netloc
+
+    if "." in domain:
+        return domain.split(".")[1]
+    else:
+        return "us-east-1"

moto/backends.py

@@ -6,6 +6,10 @@ BACKENDS = {
     "acm": ("acm", "acm_backends"),
     "apigateway": ("apigateway", "apigateway_backends"),
     "athena": ("athena", "athena_backends"),
+    "applicationautoscaling": (
+        "applicationautoscaling",
+        "applicationautoscaling_backends",
+    ),
     "autoscaling": ("autoscaling", "autoscaling_backends"),
     "batch": ("batch", "batch_backends"),
     "cloudformation": ("cloudformation", "cloudformation_backends"),