Minimum Terraform for AWS API Gateway <-> Lambda

lambda.py

import json

def handler(event, context):
    return {
        "statusCode": 200,
	'headers': {'Content-Type': 'application/json'},
        "body": json.dumps('Hi!')
    }

lambda.tf

# As long as your lambda adheres to expected API Gateway format, this is all you'll need
# API Gateway
# Define the use of rest API
resource "aws_api_gateway_rest_api" "api" {
  name = format("app_name-%s", terraform.workspace)
}

# The resource for the endpoint
resource "aws_api_gateway_resource" "lambda" {
  path_part   = "ENDPOINT_HERE"
  parent_id   = aws_api_gateway_rest_api.api.root_resource_id
  rest_api_id = aws_api_gateway_rest_api.api.id
}

# How the gateway will be interacted from clientt
resource "aws_api_gateway_method" "lambda" {
  rest_api_id   = aws_api_gateway_rest_api.api.id
  resource_id   = aws_api_gateway_resource.lambda.id
  http_method   = "GET"
  authorization = "NONE"
}

# Integration between lambda and terraform
resource "aws_api_gateway_integration" "redirect" {
  rest_api_id = aws_api_gateway_rest_api.api_gateway_rest_api.id
  resource_id = aws_api_gateway_resource.lambda.id
  http_method = aws_api_gateway_method.lambda.http_method
  # Lambda invokes requires a POST method
  integration_http_method = "POST"
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.lambda.invoke_arn
}

# Define Lambda
resource "aws_lambda_function" "lambda" {
  filename         = var.zip_file
  function_name    = "lambda"
  handler          = "lambda.handler"
  role             = aws_iam_role.iam_role.arn
  runtime          = "python3.7" # change accordingly
  source_code_hash = local.source_code_hash
}

# Define lambda permissions to grant API gateway, source arn is not needed
resource "aws_lambda_permission" "allow_api_gateway" {
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.lambda.function_name
  principal     = "apigateway.amazonaws.com"
}