Building Lambda functions with Python - AWS Lambda

Building Lambda functions with Python

You can run Python code in AWS Lambda. Lambda provides runtimes for Python that run your code to process events. Your code runs in an environment that includes the SDK for Python (Boto3), with credentials from an AWS Identity and Access Management (IAM) role that you manage.

Lambda supports the following Python runtimes.


End of support for the Python 2.7 runtime started on July 15, 2021. For more information, see Runtime support policy.

Python runtimes
Name Identifier AWS SDK for Python Operating system

Python 3.9


boto3-1.17.100 botocore-1.20.100

Amazon Linux 2

Python 3.8


boto3-1.17.100 botocore-1.20.100

Amazon Linux 2

Python 3.7


boto3-1.17.100 botocore-1.20.100

Amazon Linux

Python 3.6


boto3-1.17.100 botocore-1.20.100

Amazon Linux

Python 2.7


boto3-1.17.100 botocore-1.20.100

Amazon Linux

To create a Python function

  1. Open the Lambda console.

  2. Choose Create function.

  3. Configure the following settings:

    • Namemy-function.

    • RuntimePython 3.9.

    • RoleChoose an existing role.

    • Existing rolelambda-role.

  4. Choose Create function.

  5. To configure a test event, choose Test.

  6. For Event name, enter test.

  7. Choose Save changes.

  8. To invoke the function, choose Test.

The console creates a Lambda function with a single source file named lambda_function. You can edit this file and add more files in the built-in code editor. To save your changes, choose Save. Then, to run your code, choose Test.


The Lambda console uses AWS Cloud9 to provide an integrated development environment in the browser. You can also use AWS Cloud9 to develop Lambda functions in your own environment. For more information, see Working with Lambda Functions in the AWS Cloud9 user guide.


To get started with application development in your local environment, deploy one of the sample applications available in this guide's GitHub repository.

Sample Lambda applications in Python

  • blank-python – A Python function that shows the use of logging, environment variables, AWS X-Ray tracing, layers, unit tests and the AWS SDK.

Your Lambda function comes with a CloudWatch Logs log group. The function runtime sends details about each invocation to CloudWatch Logs. It relays any logs that your function outputs during invocation. If your function returns an error, Lambda formats the error and returns it to the invoker.