Lambda integration in AWS - Mini Project: Build & Apply

AWS Lambda Integration with API Gateway

📖 Scenario: You are building a simple serverless application that responds to HTTP requests. You will create an AWS Lambda function and integrate it with an API Gateway to handle web requests.

🎯 Goal: Build an AWS Lambda function and connect it to an API Gateway REST API so that HTTP GET requests trigger the Lambda function.

📋 What You'll Learn

Create a Lambda function named MyLambdaFunction with a basic handler

Create an API Gateway REST API named MyApi

Add a GET method to the root resource of MyApi

Integrate the GET method with MyLambdaFunction

💡 Why This Matters

🌍 Real World

Serverless applications often use AWS Lambda with API Gateway to create scalable web APIs without managing servers.

💼 Career

Understanding Lambda integration with API Gateway is essential for cloud developers and architects building serverless backend services.

1

Create the AWS Lambda function

Create a Lambda function named MyLambdaFunction with a runtime of python3.12 and a handler named lambda_handler. The function should return a JSON response with status code 200 and body 'Hello from Lambda!'.

AWS

# Your code here to create MyLambdaFunction with python3.12 runtime and lambda_handler

Need a hint?

Remember to create an IAM role for Lambda execution with the basic execution policy.

2

Create the API Gateway REST API

Create an API Gateway REST API resource named MyApi with a description 'API for Lambda integration'.

AWS

resource "aws_lambda_function" "MyLambdaFunction" {
  function_name = "MyLambdaFunction"
  runtime       = "python3.12"
  handler       = "lambda_handler"
  role          = aws_iam_role.lambda_exec.arn

  filename      = "lambda_function_payload.zip"

  source_code_hash = filebase64sha256("lambda_function_payload.zip")

  environment {
    variables = {}
  }
}

resource "aws_iam_role" "lambda_exec" {
  name = "lambda_exec_role"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = "sts:AssumeRole"
        Effect = "Allow"
        Principal = {
          Service = "lambda.amazonaws.com"
        }
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "lambda_policy_attach" {
  role       = aws_iam_role.lambda_exec.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}

# Your code here to create MyApi REST API

Need a hint?

Use aws_api_gateway_rest_api resource with the exact name MyApi.

3

Add GET method to API Gateway root resource

Add a GET method to the root resource of MyApi using aws_api_gateway_method. Set http_method to GET and authorization to NONE.

AWS

resource "aws_lambda_function" "MyLambdaFunction" {
  function_name = "MyLambdaFunction"
  runtime       = "python3.12"
  handler       = "lambda_handler"
  role          = aws_iam_role.lambda_exec.arn

  filename      = "lambda_function_payload.zip"

  source_code_hash = filebase64sha256("lambda_function_payload.zip")

  environment {
    variables = {}
  }
}

resource "aws_iam_role" "lambda_exec" {
  name = "lambda_exec_role"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = "sts:AssumeRole"
        Effect = "Allow"
        Principal = {
          Service = "lambda.amazonaws.com"
        }
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "lambda_policy_attach" {
  role       = aws_iam_role.lambda_exec.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}

resource "aws_api_gateway_rest_api" "MyApi" {
  name        = "MyApi"
  description = "API for Lambda integration"
}

# Your code here to add GET method to root resource

Need a hint?

Use aws_api_gateway_method with http_method = "GET" and authorization = "NONE".

4

Integrate GET method with Lambda function

Create an API Gateway integration resource named get_integration that connects the GET method of MyApi root resource to the Lambda function MyLambdaFunction. Use aws_api_gateway_integration with integration_http_method set to POST and type set to AWS_PROXY.

AWS

resource "aws_lambda_function" "MyLambdaFunction" {
  function_name = "MyLambdaFunction"
  runtime       = "python3.12"
  handler       = "lambda_handler"
  role          = aws_iam_role.lambda_exec.arn

  filename      = "lambda_function_payload.zip"

  source_code_hash = filebase64sha256("lambda_function_payload.zip")

  environment {
    variables = {}
  }
}

resource "aws_iam_role" "lambda_exec" {
  name = "lambda_exec_role"

  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = "sts:AssumeRole"
        Effect = "Allow"
        Principal = {
          Service = "lambda.amazonaws.com"
        }
      }
    ]
  })
}

resource "aws_iam_role_policy_attachment" "lambda_policy_attach" {
  role       = aws_iam_role.lambda_exec.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}

resource "aws_api_gateway_rest_api" "MyApi" {
  name        = "MyApi"
  description = "API for Lambda integration"
}

resource "aws_api_gateway_method" "get_root" {
  rest_api_id   = aws_api_gateway_rest_api.MyApi.id
  resource_id   = aws_api_gateway_rest_api.MyApi.root_resource_id
  http_method   = "GET"
  authorization = "NONE"
}

# Your code here to integrate GET method with Lambda

Need a hint?

Use aws_api_gateway_integration with type = "AWS_PROXY" and integration_http_method = "POST".