feat: add initial pre-commit config

Signed-off-by: heitorlessa <lessa@amazon.co.uk>

Author: heitorlessa

.pre-commit-config.yaml

@@ -0,0 +1,27 @@
+# We use poetry to run formatting and linting before commit/push
+# Longers checks such as tests, security and complexity baseline
+# are run as part of CI to prevent slower feedback loop
+# All checks can be run locally via `make pr`
+
+repos:
+    - repo: local
+      hooks:
+          - id: black
+            name: formatting::black
+            entry: poetry run black
+            language: system
+            types: [python]
+          - id: isort
+            name: formatting::isort
+            entry: poetry run isort -rc
+            language: system
+            types: [python]
+    - repo: local
+      hooks:
+          - id: flake8
+            name: linting::flake8
+            entry: poetry run flake8
+            language: system
+            types: [python]
+            exclude: example 
+fail_fast: true

example/hello_world/app.py

@@ -20,7 +20,7 @@
 
 _cold_start = True
 
-metrics.add_dimension(name="operation", value="example") # added at cold start only
+metrics.add_dimension(name="operation", value="example")  # added at cold start only
 
 
 async def aioboto_task():

example/tests/test_handler.py

@@ -5,6 +5,7 @@
 
 from hello_world import app
 
+
 @pytest.fixture()
 def apigw_event():
     """ Generates API GW Event"""
@@ -61,30 +62,32 @@ def apigw_event():
         "path": "/examplepath",
     }
 
+
 @dataclass
 class Context:
     function_name: str = "test"
     memory_limit_in_mb: int = 128
     invoked_function_arn: str = "arn:aws:lambda:eu-west-1:298026489:function:test"
     aws_request_id: str = "5b441b59-a550-11c8-6564-f1c833cf438c"
 
+
 def test_lambda_handler(apigw_event, mocker, capsys):
     ret = app.lambda_handler(apigw_event, Context())
     data = json.loads(ret["body"])
 
     output = capsys.readouterr()
-    output = output.out.split('\n')
-    stdout_one_string = '\t'.join(output)
+    output = output.out.split("\n")
+    stdout_one_string = "\t".join(output)
 
     assert ret["statusCode"] == 200
     assert data["message"] == "hello world"
     assert "location" in data
     assert "message" in ret["body"]
     assert "async_http" in data
-    
+
     # assess custom metric was flushed in stdout/logs
-    assert "SuccessfulLocations" in stdout_one_string 
-    assert "ColdStart" in stdout_one_string 
+    assert "SuccessfulLocations" in stdout_one_string
+    assert "ColdStart" in stdout_one_string
     assert "UniqueMetricDimension" in stdout_one_string
 
     # assess our custom middleware ran