Lambda reserved concurrency (#3215)

* lambda-responses: add method to dispatch concurrency calls

* lambda-resources: add route to handle concurrency requests

* lambda-model: implement put_function_concurrency and concurrency attribute

* put-concurrency-tests: add one simple test

* get_function: add concurrency entry - with test

* lambda-reserved-concurrency: cloudformation support

* lambda-concurrency: implement delete_reserved with tests

* lambda-concurrency: implement get_reserved with tests

* lint

* implementation-cov: mark delete_function_concurrency, put_function_concurrency and get_function_concurrency

* botocore doesn't display concurrency entry for lambdas without it

* lambda(refactor): improvements on response's handler

tests/test_awslambda/test_lambda.py

@@ -489,7 +489,7 @@ def test_get_function():
         {"test_variable": "test_value"}
     )
 
-    # Test get function with
+    # Test get function with qualifier
     result = conn.get_function(FunctionName="testFunction", Qualifier="$LATEST")
     result["Configuration"]["Version"].should.equal("$LATEST")
     result["Configuration"]["FunctionArn"].should.equal(
@@ -1721,6 +1721,82 @@ def test_remove_function_permission():
     policy["Statement"].should.equal([])
 
 
+@mock_lambda
+def test_put_function_concurrency():
+    expected_concurrency = 15
+    function_name = "test"
+
+    conn = boto3.client("lambda", _lambda_region)
+    conn.create_function(
+        FunctionName=function_name,
+        Runtime="python3.8",
+        Role=(get_role_name()),
+        Handler="lambda_function.handler",
+        Code={"ZipFile": get_test_zip_file1()},
+        Description="test lambda function",
+        Timeout=3,
+        MemorySize=128,
+        Publish=True,
+    )
+    result = conn.put_function_concurrency(
+        FunctionName=function_name, ReservedConcurrentExecutions=expected_concurrency
+    )
+
+    result["ReservedConcurrentExecutions"].should.equal(expected_concurrency)
+
+
+@mock_lambda
+def test_delete_function_concurrency():
+    function_name = "test"
+
+    conn = boto3.client("lambda", _lambda_region)
+    conn.create_function(
+        FunctionName=function_name,
+        Runtime="python3.8",
+        Role=(get_role_name()),
+        Handler="lambda_function.handler",
+        Code={"ZipFile": get_test_zip_file1()},
+        Description="test lambda function",
+        Timeout=3,
+        MemorySize=128,
+        Publish=True,
+    )
+    conn.put_function_concurrency(
+        FunctionName=function_name, ReservedConcurrentExecutions=15
+    )
+
+    conn.delete_function_concurrency(FunctionName=function_name)
+    result = conn.get_function(FunctionName=function_name)
+
+    result.doesnt.have.key("Concurrency")
+
+
+@mock_lambda
+def test_get_function_concurrency():
+    expected_concurrency = 15
+    function_name = "test"
+
+    conn = boto3.client("lambda", _lambda_region)
+    conn.create_function(
+        FunctionName=function_name,
+        Runtime="python3.8",
+        Role=(get_role_name()),
+        Handler="lambda_function.handler",
+        Code={"ZipFile": get_test_zip_file1()},
+        Description="test lambda function",
+        Timeout=3,
+        MemorySize=128,
+        Publish=True,
+    )
+    conn.put_function_concurrency(
+        FunctionName=function_name, ReservedConcurrentExecutions=expected_concurrency
+    )
+
+    result = conn.get_function_concurrency(FunctionName=function_name)
+
+    result["ReservedConcurrentExecutions"].should.equal(expected_concurrency)
+
+
 def create_invalid_lambda(role):
     conn = boto3.client("lambda", _lambda_region)
     zip_content = get_test_zip_file1()

tests/test_cloudformation/test_cloudformation_stack_integration.py

@@ -1777,6 +1777,7 @@ def lambda_handler(event, context):
                     "Role": {"Fn::GetAtt": ["MyRole", "Arn"]},
                     "Runtime": "python2.7",
                     "Environment": {"Variables": {"TEST_ENV_KEY": "test-env-val"}},
+                    "ReservedConcurrentExecutions": 10,
                 },
             },
             "MyRole": {
@@ -1811,6 +1812,11 @@ def lambda_handler(event, context):
         {"Variables": {"TEST_ENV_KEY": "test-env-val"}}
     )
 
+    function_name = result["Functions"][0]["FunctionName"]
+    result = conn.get_function(FunctionName=function_name)
+
+    result["Concurrency"]["ReservedConcurrentExecutions"].should.equal(10)
+
 
 @mock_cloudformation
 @mock_ec2