refactor: env vars multiple handlers local tests support, update pip (#23)

Author: ran-isenberg

Pipfile

@@ -22,6 +22,7 @@ isort = "*"
 boto3 = "*"
 mkdocs-material = "*"
 mkdocs-git-revision-date-plugin = "*"
+cattrs = "==1.10.0"
 
 [packages]
 pydantic = {extras = ["email"],version = "*"}

Pipfile.lock

@@ -1,17 +1,17 @@
 -i https://pypi.org/simple
 -e ./cdk
 attrs==21.4.0
-aws-cdk-lib==2.19.0
+aws-cdk-lib==2.20.0
 aws-cdk.aws-lambda-python-alpha==2.19.0a0
-boto3==1.21.32
-botocore==1.24.32
-cattrs==1.10.0 ; python_version >= '3.7'
+boto3==1.21.39
+botocore==1.24.39
+cattrs==1.10.0
 certifi==2021.10.8
 cfgv==3.3.1
 charset-normalizer==2.0.12 ; python_version >= '3'
 click==8.1.2
 colorama==0.4.4 ; python_version > '3.4'
-constructs==10.0.104
+constructs==10.0.113
 coverage[toml]==6.3.2
 distlib==0.3.4
 filelock==3.6.0
@@ -27,15 +27,15 @@ iniconfig==1.1.1
 isort==5.10.1
 jinja2==3.1.1
 jmespath==0.10.0
-jsii==1.55.1
+jsii==1.56.0
 mando==0.6.4
 markdown==3.3.6
 markupsafe==2.1.1
 mccabe==0.6.1
 mergedeep==1.3.4
 mkdocs-git-revision-date-plugin==0.3.2
 mkdocs-material-extensions==1.0.3
-mkdocs-material==8.2.8
+mkdocs-material==8.2.9
 mkdocs==1.3.0
 nodeenv==1.6.0
 packaging==21.3
@@ -48,7 +48,7 @@ pycodestyle==2.8.0
 pyflakes==2.4.0
 pygments==2.11.2
 pymdown-extensions==9.3
-pyparsing==3.0.7
+pyparsing==3.0.8
 pytest-cov==3.0.0
 pytest-html==3.1.1
 pytest-metadata==2.0.1
@@ -67,8 +67,8 @@ toml==0.10.2
 tomli==2.0.1
 typing-extensions==4.1.1
 urllib3==1.26.9
-virtualenv==20.14.0
+virtualenv==20.14.1
 watchdog==2.1.7
 xenon==0.9.0
 yapf==0.32.0
-zipp==3.7.0
+zipp==3.8.0

dev_requirements.txt

@@ -100,7 +100,7 @@ It can be used *anywhere* in the function code, not just the handler.
 
     @init_environment_variables(model=MyHandlerEnvVars)
     def my_handler(event: Dict[str, Any], context: LambdaContext) -> Dict[str, Any]:
-        env_vars: MyHandlerEnvVars = get_environment_variables()
+        env_vars: MyHandlerEnvVars = get_environment_variables(model=MyHandlerEnvVars)
         return {'statusCode': HTTPStatus.OK, 'headers': {'Content-Type': 'application/json'}, 'body': json.dumps({'message': 'success'})}
     ```
 

docs/best_practices/environment_variables.md

@@ -1,8 +1,8 @@
 -i https://pypi.org/simple
-aws-lambda-powertools==1.25.6
+aws-lambda-powertools==1.25.7
 aws-xray-sdk==2.9.0
-boto3==1.21.32
-botocore==1.24.32
+boto3==1.21.39
+botocore==1.24.39
 dnspython==2.2.1
 email-validator==1.1.3
 fastjsonschema==2.15.3

lambda_requirements.txt

@@ -26,7 +26,7 @@ def my_handler(event: Dict[str, Any], context: LambdaContext) -> Dict[str, Any]:
     logger.set_correlation_id(context.aws_request_id)
     logger.info('my_handler is called, calling inner_function_example')
 
-    env_vars: MyHandlerEnvVars = get_environment_variables()
+    env_vars: MyHandlerEnvVars = get_environment_variables(model=MyHandlerEnvVars)
     logger.debug('environment variables', extra=env_vars.dict())
 
     try:

service/handlers/my_handler.py

@@ -1,35 +1,26 @@
 import os
+from functools import lru_cache
 from typing import Any, TypeVar
 
 from aws_lambda_powertools.middleware_factory import lambda_handler_decorator
 from pydantic import BaseModel, ValidationError
 
 Model = TypeVar('Model', bound=BaseModel)
 
-# global instance of the parsed Pydantic data class
-ENV_CONF: BaseModel = None
 
-
-@lambda_handler_decorator
-def init_environment_variables(handler, event, context, model: Model) -> Any:
-    global ENV_CONF
+@lru_cache
+def __parse_model(model: Model) -> BaseModel:
     try:
-        # parse the os environment variables dict
-        ENV_CONF = model(**os.environ)
+        return model(**os.environ)
     except (ValidationError, TypeError) as exc:
         raise ValueError(f'failed to load environment variables, exception={str(exc)}') from exc
 
-    return handler(event, context)
-
 
-def get_environment_variables() -> BaseModel:
-    global ENV_CONF
-    if ENV_CONF is None:
-        raise ValueError('get_environment_variables was called before init_environment_variables, environment variables were not loaded')
-    return ENV_CONF
+@lambda_handler_decorator
+def init_environment_variables(handler, event, context, model: Model) -> Any:
+    __parse_model(model)
+    return handler(event, context)
 
 
-# used for testing purposes
-def _clear_env_conf() -> None:
-    global ENV_CONF
-    ENV_CONF = None
+def get_environment_variables(model: Model) -> BaseModel:
+    return __parse_model(model)

service/handlers/utils/env_vars_parser.py

@@ -6,7 +6,7 @@
 from pydantic import BaseModel, HttpUrl
 
 from cdk.aws_lambda_handler_cookbook.service_stack.constants import POWER_TOOLS_LOG_LEVEL, POWERTOOLS_SERVICE_NAME, SERVICE_NAME
-from service.handlers.utils.env_vars_parser import _clear_env_conf, get_environment_variables, init_environment_variables
+from service.handlers.utils.env_vars_parser import get_environment_variables, init_environment_variables
 from tests.utils import generate_context
 
 
@@ -16,25 +16,6 @@ class MySchema(BaseModel):
     REST_API: HttpUrl
 
 
-@mock.patch.dict(os.environ, {
-    POWERTOOLS_SERVICE_NAME: SERVICE_NAME,
-    POWER_TOOLS_LOG_LEVEL: 'DEBUG',
-    'REST_API': 'https://www.ranthebuilder.cloud/api'
-})
-def test_handler_schema_ok():
-
-    @init_environment_variables(model=MySchema)
-    def my_handler(event, context) -> Dict[str, Any]:
-        env_vars: MySchema = get_environment_variables()
-        assert env_vars.POWERTOOLS_SERVICE_NAME == SERVICE_NAME
-        assert env_vars.LOG_LEVEL == 'DEBUG'
-        assert str(env_vars.REST_API) == 'https://www.ranthebuilder.cloud/api'
-        return {}
-
-    my_handler({}, generate_context())
-    _clear_env_conf()
-
-
 def test_handler_missing_env_var():
 
     @init_environment_variables(model=MySchema)
@@ -56,12 +37,19 @@ def my_handler2(event, context) -> Dict[str, Any]:
         my_handler2({}, generate_context())
 
 
-@mock.patch.dict(os.environ, {POWERTOOLS_SERVICE_NAME: SERVICE_NAME, POWER_TOOLS_LOG_LEVEL: 'DEBUG', 'REST_API': 'fakeapi'})
-def test_handler_get_env_var_without_init():
+@mock.patch.dict(os.environ, {
+    POWERTOOLS_SERVICE_NAME: SERVICE_NAME,
+    POWER_TOOLS_LOG_LEVEL: 'DEBUG',
+    'REST_API': 'https://www.ranthebuilder.cloud/api'
+})
+def test_handler_schema_ok():
 
-    def my_handler3(event, context) -> Dict[str, Any]:
-        get_environment_variables()
+    @init_environment_variables(model=MySchema)
+    def my_handler(event, context) -> Dict[str, Any]:
+        env_vars: MySchema = get_environment_variables(model=MySchema)
+        assert env_vars.POWERTOOLS_SERVICE_NAME == SERVICE_NAME
+        assert env_vars.LOG_LEVEL == 'DEBUG'
+        assert str(env_vars.REST_API) == 'https://www.ranthebuilder.cloud/api'
         return {}
 
-    with pytest.raises(ValueError):
-        my_handler3({}, generate_context())
+    my_handler({}, generate_context())