如何导入LambdaContext？

Question

我在做AWS Lambda函数。 现在我想isinstance(context,LambdaContext)，我希望它能在AWS Lambda中工作。 但我在本地运行单元测试。在

那么如何导入LambdaContext。在

最佳

Answer 1

在/var/runtime/awslambda中定义的LambdaContext类/鞋带用于启动用户功能，具有以下结构：

class LambdaContext(object):
    def __init__(self, invokeid, context_objs, client_context, invoked_function_arn=None):
        self.aws_request_id = invokeid
        self.log_group_name = os.environ['AWS_LAMBDA_LOG_GROUP_NAME']
        self.log_stream_name = os.environ['AWS_LAMBDA_LOG_STREAM_NAME']
        self.function_name = os.environ["AWS_LAMBDA_FUNCTION_NAME"]
        self.memory_limit_in_mb = os.environ['AWS_LAMBDA_FUNCTION_MEMORY_SIZE']
        self.function_version = os.environ['AWS_LAMBDA_FUNCTION_VERSION']
        self.invoked_function_arn = invoked_function_arn

        self.client_context = make_obj_from_dict(ClientContext, client_context)
        if self.client_context is not None:
            self.client_context.client = make_obj_from_dict(Client, self.client_context.client)
        self.identity = make_obj_from_dict(CognitoIdentity, context_objs)

    def get_remaining_time_in_millis(self):
        return lambda_runtime.get_remaining_time()

    def log(self, msg):
        str_msg = str(msg)
        lambda_runtime.send_console_message(str_msg, byte_len(str_msg))

如果要在本地环境中模拟它，只需将其添加到脚本中：

^{pr2}$

Answer 2

这不是严格意义上的回答，如果不合适，请删除。在

我尝试过@Dmitry Masanov的答案，并为pytest准备了一个python fixture，它既可以在测试脚本中使用，也可以在conftest.py文件中使用。在

@pytest.fixture
def mock_lambda_context():
    class ClientContext:
        """
        Class for mocking Context

        Has `custom`, `env`, and `client` `__slots__`
        """

        __slots__ = ["custom", "env", "client"]

    def make_obj_from_dict(_class, _dict, fields=None):
        """
        Makes an object of `_class` from a `dict`

        :param _class: A class representing the context
        :type _class: `ContextClass`
        :param _dict: A dictionary of data 
        :type _dict: `dict`
        :param fields: [description], defaults to None
        :type fields: [type], optional
        :return: An object
        :rtype: `ClientContext` class
        """
        if _dict is None:
            return None
        obj = _class()
        set_obj_from_dict(obj, _dict)
        return obj

    def set_obj_from_dict(obj, _dict, fields=None):
        if fields is None:
            fields = obj.__class__.__slots__
        for field in fields:
            setattr(obj, field, _dict.get(field, None))

    class LambdaContext(object):
        """
        Create a Lambda Context Class object
        """

        def __init__(self, invokeid, client_context, invoked_function_arn=None):
            self.aws_request_id = invokeid
            self.log_group_name = "AWS_LAMBDA_LOG_GROUP_NAME"
            self.log_stream_name = "AWS_LAMBDA_LOG_STREAM_NAME"
            self.function_name = "AWS_LAMBDA_FUNCTION_NAME"
            self.memory_limit_in_mb = "AWS_LAMBDA_FUNCTION_MEMORY_SIZE"
            self.function_version = "AWS_LAMBDA_FUNCTION_VERSION"
            self.invoked_function_arn = invoked_function_arn

            self.client_context = make_obj_from_dict(ClientContext, client_context)
            if self.client_context is not None:
                self.client_context.client = None
            self.identity = None

        def get_remaining_time_in_millis(self):
            return None

        def log(self, msg):
            str_msg = str(msg)
            print(str_msg)

    lambda_context = LambdaContext("AWS_ID", {})

    return lambda_context

我几乎可以肯定我的实现是可以改进的（OO python不是我的强项），但这符合我的目的：

• 模拟lambda上下文对象
• 与pytest集成

其使用方法与此类似：

^{pr2}$

再次感谢德米特里，你的回答帮我省了不少麻烦。在

Answer 3

您可以尝试使用LocalStack：

LocalStack provides an easy-to-use test/mocking framework for developing Cloud applications.

Currently, the focus is primarily on supporting the AWS cloud stack.

LocalStack spins up the following core Cloud APIs on your local machine:

API Gateway at http://localhost:4567

Kinesis at http://localhost:4568

DynamoDB at http://localhost:4569

DynamoDB Streams at http://localhost:4570

Elasticsearch at http://localhost:4571

S3 at http://localhost:4572

Firehose at http://localhost:4573

Lambda at http://localhost:4574

SNS at http://localhost:4575

SQS at http://localhost:4576

Redshift at http://localhost:4577

ES (Elasticsearch Service) at http://localhost:4578

SES at http://localhost:4579

Route53 at http://localhost:4580

CloudFormation at http://localhost:4581

CloudWatch at http://localhost:4582