In Java, we can implement RequestHandler and override method handleRequest(paremeters).This way, you can pass the input to the Lambda handle request.
For Python, you can take a look at below examples from AWS Docs: https://docs.aws.amazon.com/lambda/latest/dg/python-handler.html
In short(as per AWS Docs), The Lambda function handler is the method in your function code that processes events. When your function is invoked, Lambda runs the handler method. When the handler exits or returns a response, it becomes available to handle another event.
Hope this helps.
Answer from Avinash Akella on Stack OverflowAmazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › building lambda functions with python › define lambda function handler in python
Define Lambda function handler in Python - AWS Lambda
January 31, 2026 - The Lambda function handler is the method in your Python code that processes events. When your function is invoked, Lambda runs the handler method.
GeeksforGeeks
geeksforgeeks.org › cloud computing › lambda-function-handler-in-python
Lambda Function Handler In Python - GeeksforGeeks
July 23, 2025 - AWS Lambda handler function contains two arguments, event and context as seen in the above default code of lambda_function.py file. An event is generally a JSON Formatted String that contains the data that was passed by the external sources when invoking a Lambda function. It is usually of the 'dict' type in python but it can also be other types, such as 'list', 'int', 'float', etc.
amazon web services - How the handler of a Lambda Function works? - Stack Overflow
I want to call this Lambda Function with a payload, for example a username that I will choose: { "iamuser": "Joe" } I don't understand how the handler of a Lambda function wo... More on stackoverflow.com
ELI5 Lambda Handler?
It's basically the starting point of running your code. When AWS starts your lambda it will invoke/call the handler function. More on reddit.com
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April 12, 2022Getting started with Python AWS Lamda function? - SST Guide Forums
After creating a new SST application with: npx create-sst@latest my-sst-app There is a lambda function provided as a “hello world” example in /packages/functions/src/lambda.ts. I have some python code that I want to r… More on discourse.sst.dev
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November 2, 2023amazon web services - Does the python script have to be named as handler.py in AWS Lambda - Stack Overflow
Does the python script have to be named as handler.py in AWS Lambda? I can't remember where I read this from, it says lambda is configured to look for a specific file, usually named 'handler.py',just More on stackoverflow.com
Videos
06:02
Code Default Arguments in AWS Lambda Functions - YouTube
09:44
AWS with Python: Mastering Lambda Basics - YouTube
32:01
Intro to AWS Lambda with Python | AWS Lambda Python Tutorial - YouTube
26:21
AWS Lambda For Absolute Beginners: Python Tutorial in 25 Minutes ...
06:11
AWS Lambda Using Python | AWS Lambda Tutorial For Beginners | ...
12:40
5. AWS Lambda Batch - HANDS-ON : Write Python Code from Lambda ...
Readthedocs
aws-lambda-for-python-developers.readthedocs.io › en › latest › 02_event_and_context
Chapter 2: What is the event & context? - AWS Lambda for Python Developers
Handler functions must always take two arguments, event and context, and they may return a value, in short they always have to look like this: def lambda_handler(event, context): ...
PyPI
pypi.org › project › lambda-handlers
lambda-handlers · PyPI
An opinionated Python package that facilitates specifying AWS Lambda handlers including input validation, error handling and response formatting.
» pip install lambda-handlers
GitHub
github.com › ran-isenberg › aws-lambda-handler-cookbook
GitHub - ran-isenberg/aws-lambda-handler-cookbook: This repository provides a working, deployable, open source-based, serverless service blueprint with an AWS Lambda function and AWS CDK Python code with all the best practices and a complete CI/CD pipeline. · GitHub
This project provides a working, open source based, AWS Lambda handler skeleton Python code includingx DEPLOYMENT code with CDK and a pipeline.
Starred by 670 users
Forked by 60 users
Languages Python 95.9% | Makefile 4.1%
Stackify
stackify.com › aws-lambda-with-python-a-complete-getting-started-guide
AWS Lambda with Python: A Complete Getting Started Guide - Stackify
May 16, 2024 - As an example, if our function is called handler and it’s in the file named main.py, the Handler value needs to be set to main.handler. The below screenshot shows how this ties together: While you can run this example now as is, there’s one more change to make, for illustration purposes. Add a print statement to the code as in this example: import json def lambda_handler(event, context): print("Hello from Lambda!") return { 'statusCode': 200, 'body': json.dumps('Hello from Lambda!') }
Amazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › building lambda functions with python › using the lambda context object to retrieve python function information
Using the Lambda context object to retrieve Python function information - AWS Lambda
When Lambda runs your function, it passes a context object to the handler. This object provides methods and properties that provide information about the invocation, function, and execution environment. For more information on how the context object is passed to the function handler, see Define Lambda function handler in Python.
Datadog
docs.datadoghq.com › serverless › guide › handler_wrapper
Wrap Your Lambda Handler in Code
Skip the step to set the environment variable DD_LAMBDA_HANDLER. ... # for python from datadog_lambda.wrapper import datadog_lambda_wrapper @datadog_lambda_wrapper def my_lambda_handle(event, context): # your function code
Reddit
reddit.com › r/aws › eli5 lambda handler?
r/aws on Reddit: ELI5 Lambda Handler?
April 12, 2022 -
I'm relatively new to AWS and computing in general, so can someone explain in very basic terms what a lambda handler is/does?
I read the definition from AWS documentation, but it is still a little bit confusing. What does it mean to be a "method of entry point" for you code?
Top answer 1 of 3
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It's basically the starting point of running your code. When AWS starts your lambda it will invoke/call the handler function.
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assuming you use python, the aws provided environment will do something similar to import lambda_function while True: event = get_event_from_aws() lambda_function.lambda_handler(event) report_success_to_aws() where "lambda_function" and "lambda_handler" can be configured. so yes, basically you need to provide a function for the lambda environment to call. obviously the above code is just an illustration, a lot of other bookkeeping and error handling happens.
Amazon Web Services
docs.aws.amazon.com › aws lambda › developer guide › building lambda functions with python
Building Lambda functions with Python - AWS Lambda
The version of the AWS SDK included in the Python runtime depends on the runtime version and your AWS Region. To find the version of the SDK included in the runtime you're using, create a Lambda function with the following code. import boto3 import botocore def lambda_handler(event, context): print(f'boto3 version: {boto3.__version__}') print(f'botocore version: {botocore.__version__}')
Open Source at AWS
aws.github.io › aws-pdk › developer_guides › type-safe-api › lambda_handlers.html
Lambda Handlers - AWS Project Development Kit (PDK)
For TypeScript and Java, you may need to override the package task for the handlers project to run the appropriate commands to build your handlers with their native dependencies, or consider consuming them using a Lambda layer. You can configure the desired runtime versions of your handler projects in your .projenrc. This adjusts the appropriate project settings (such as the language level and packaging command), as well as configures the function CDK constructs to target this runtime version. ... new TypeSafeApiProject({ ... handlers: { languages: [Language.PYTHON, Language.JAVA, Language.TYPESCRIPT], options: { python: { runtimeVersion: PythonVersion.PYTHON_3_12, }, java: { runtimeVersion: JavaVersion.JAVA_21, }, typescript: { runtimeVersion: NodeVersion.NODE_20, }, } } });
SST Guide Forums
discourse.sst.dev › t › getting-started-with-python-aws-lamda-function › 2890
Getting started with Python AWS Lamda function? - SST Guide Forums
November 2, 2023 - After creating a new SST application with: npx create-sst@latest my-sst-app There is a lambda function provided as a “hello world” example in /packages/functions/src/lambda.ts. I have some python code that I want to run as an API. But to get started, here is a little hello world in Python: import json def lambda_handler(event, context): print("Hello from Lambda!") return { 'statusCode': 200, 'body': json.dumps('Hello from Lambda!') } How do I go about deploying ...
Medium
medium.com › @reach2shristi.81 › starting-your-lambda-journey-with-python-74d95346dd0
Starting your Lambda Journey with Python | by Min_Minu | Medium
June 25, 2023 - You can use the json module to convert Python objects to JSON format when constructing the response. ... import json def lambda_handler(event, context): # This is how we can extract information from the event object name = event['name'] age = event['age'] # Perform your processing and logic if age >= 18: message = f"Hello {name}, you are an adult!" else: message = f"Hello {name}, you are underage!"
Manilafunctional
manilafunctional.com › post › writing-better-aws-lambda-handlers-in-python.html
Writing Better Python AWS Lambda Handlers - Manila Functional
You can work around this project organization conundrum using Python callables: class MyHandler(): def __init__(): pass @staticmethod def __my_helper(): return "helped!" def __call__(event, context): return self.__my_helper() handler = MyHandler() AWS Lambda will then call the variable handler, like so handler(event, context).
GitHub
gist.github.com › benkehoe › efb75a793f11d071b36fed155f017c8f
Code pattern for implementing class-based AWS Lambda handlers in Python · GitHub
I found this code very useful but didn't like the repetition of handler = MyLambdaClass.get_handler(...) for each class. Instead, I created an annotation tag, so I can now do: @LambdaHandler class MyLambdaClass(LambdaBase): def __init__(self, ...): # implementation-specific args and/or kwargs # implementation def handle(self, event, context): # implementation def LambdaHandler(func): # Creates dynamic handler in caller's module called MyCallingClassHandler module = func.__module__ handler_name = f'{func.__name__}Handler' setattr(sys.modules[module], handler_name, func.get_handler() ) return func
Kevinhakanson
kevinhakanson.com › 2022-04-10-python-typings-for-aws-lambda-function-events
Python Typings for AWS Lambda Function Events | kevinhakanson.com
I was building a Python-based AWS Lambda function similar to what was announced by New – Use Amazon S3 Event Notifications with Amazon EventBridge and the code looked similar to this - full of “magic strings” that I had to discover. import boto3 def lambda_handler(event, context): bucket = event['detail']['bucket']['name'] file_key = event['detail']['object']['key'] s3 = boto3.client('s3') file_to_process = s3.get_object(Bucket=bucket, Key=file_key)
Top answer 1 of 3
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You can name this Python script whatever you want. Be sure to reference it properly.
You can tell the Lambda runtime which handler method to invoke by setting the handler parameter on your function's configuration.
When you configure a function in Python, the value of the handler setting is the file name and the name of the handler module, separated by a dot. For example,
main.Handlercalls theHandlermethod defined inmain.py.
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Does the python script have to be named as handler.py in AWS Lambda
Shortly No, you could specify any method which could process lambda event. (Usually combination is event + context (event, context)
Just wondering where we can configure this or does it have to be 'handler.py'?
It really depends how you build and deploy your lambda but shortly handler property is telling you which method to be invoked and you could specify is as relative path to your deployment package - https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-lambda-function.html#cfn-lambda-function-handler.
- template.yml
CopyLambdaFunction:
Type: AWS::Lambda::Function
Properties:
Handler: index.handler
- serverless framework In your serverless.yml file you need to define functions with handler https://www.serverless.com/framework/docs/providers/aws/guide/functions/
- aws cli https://docs.aws.amazon.com/lambda/latest/dg/python-package.html
SentinelOne
sentinelone.com › blog › aws-lambda-with-python
AWS Lambda With Python: A Simple Introduction With Examples
April 13, 2024 - service: email-validator provider: name: aws runtime: python3.8 functions: main: handler: handler.validate events: - http: POST /email/validate · See those last two lines? That means we’ll create an API Gateway with a single endpoint. Whenever a HTTP call is made to that endpoint, AWS will route it through to our Lambda function.
LinkedIn
linkedin.com › pulse › aws-lambda-handler-function-chandra-vadrevu
AWS Lambda Handler Function :-) :-)
April 14, 2022 - # aws python module boto3 to interact with AWS interface import boto3 module # create a client to work with AWS s3_client = boto3.client("s3") import dynamodb boto3 module dynamodb = boto3.resource("dynamodb") # now map table within dynamodb table = dynamodb.Table("Cloudtech_students") Lambda Handler function def lambda_handler(event, context): # create object to get event payload dictionary values -- get bucket name bucket_name = event['Records'][0]['s3']['bucket']['name'] # create object to get event payload dictionary values -- get file name s3_file_name = event['Records'][0]['s3']['object'