Create a Lambda function using AWS CloudFormation with Python code

What is CloudFormation in AWS

AWS CloudFormation is a service that gives developers and businesses an easy way to create a collection of re lated AWS and third-party resources, and provision and manage them in an orderly and predictable fashion.

Create a Lambda function

To create a Lambda function using AWS CloudFormation with Python code, you need to define the Lambda function resource within your CloudFormation template. Here’s a step-by-step example of how to do this:

CFN stack

Below is a CloudFormation template in YAML format that defines a Lambda function written in Python hello message

AWSTemplateFormatVersion: '2010-09-09'
Description: CloudFormation template for a Lambda function

Resources:
  MyLambdaFunction:
    Type: AWS::Lambda::Function
    Properties:
      Handler: lambda_function.lambda_handler
      Runtime: python3.8
      Timeout: 30
      MemorySize: 128
      Code:
        ZipFile: |
          import json

          def lambda_handler(event, context):
              print("Hello from Lambda!")
              return {
                  'statusCode': 200,
                  'body': json.dumps('Hello from Lambda!')
              }

• AWSTemplateFormatVersion: Specifies the AWS CloudFormation template version.

• Description: Provides a description of the CloudFormation template.

• Resources: Defines the AWS resources to be created or managed by this CloudFormation stack.

  • MyLambdaFunction: Defines a Lambda function resource.

    • Type: Specifies the AWS resource type (AWS::Lambda::Function).

    • Properties: Specifies the configuration properties for the Lambda function.

      • Handler: Specifies the name of the Lambda function handler. Here, lambda_function refers to the Python file (lambda_function.py) and lambda_handler is the function inside that file that will be invoked.

      • Runtime: Specifies the runtime environment for the Lambda function. Here, it's set to python3.8.

      • Timeout: Specifies the function execution timeout in seconds.

      • MemorySize: Specifies the amount of memory in MB allocated to the Lambda function.

      • Code: Specifies the function code. In this example, ZipFile contains the Python code for the Lambda function.

Deploying the CloudFormation Template:

aws cloudformation create-stack --stack-name MyLambdaStack --template-body file://lambda-template.yaml --capabilities CAPABILITY_IAM

Run or Invoke lambda function

    aws lambda invoke --function-name MyLambdaFunction output.txt