Deploying a Serverless Application Using Terraform

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Serverless architectures have transformed cloud computing by eliminating infrastructure management while ensuring high scalability and cost efficiency. In this guide, we will deploy a serverless application using Terraform, leveraging AWS Lambda, API Gateway, and S3 to build a fully automated and scalable solution.

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Why Serverless?

No infrastructure management
Auto-scaling based on demand
Pay-per-use pricing model
Faster development and deployment

Steps to Deploy the Serverless Application

We will:

Set up infrastructure with Terraform.
Package and deploy a Lambda function.
Integrate it with API Gateway.
Test the entire workflow.

Task 1: Create Infrastructure

1. Create a Directory and Configure Terraform

mkdir serverless &amp;&amp; cd serverless

1	mkdir serverless && cd serverless

2. Define AWS Provider and S3 Bucket

Create main.tf:

provider "aws" {  
  region = var.aws_region  
}  

resource "random_pet" "lambda_bucket_name" {  
  prefix = "learn-terraform-functions"  
  length = 4  
}  

resource "aws_s3_bucket" "lambda_bucket" {  
  bucket = random_pet.lambda_bucket_name.id  
}  

resource "aws_s3_bucket_ownership_controls" "lambda_bucket" {  
  bucket = aws_s3_bucket.lambda_bucket.id  
  rule {  
    object_ownership = "BucketOwnerPreferred"  
  }  
}  

resource "aws_s3_bucket_acl" "lambda_bucket" {  
  depends_on = [aws_s3_bucket_ownership_controls.lambda_bucket]  
  bucket = aws_s3_bucket.lambda_bucket.id  
  acl    = "private"  
}

provider "aws" {

region = var.aws_region

}

resource "random_pet" "lambda_bucket_name" {

prefix = "learn-terraform-functions"

length = 4

}

resource "aws_s3_bucket" "lambda_bucket" {

bucket = random_pet.lambda_bucket_name.id

}

resource "aws_s3_bucket_ownership_controls" "lambda_bucket" {

bucket = aws_s3_bucket.lambda_bucket.id

rule {

object_ownership = "BucketOwnerPreferred"

}

resource "aws_s3_bucket_acl" "lambda_bucket" {

depends_on = [aws_s3_bucket_ownership_controls.lambda_bucket]

bucket = aws_s3_bucket.lambda_bucket.id

acl = "private"

}

3. Define Outputs

Create output.tf:

output "lambda_bucket_name" {  
  description = "Name of the S3 bucket used to store function code."  
  value = aws_s3_bucket.lambda_bucket.id  
}

output "lambda_bucket_name" {

description = "Name of the S3 bucket used to store function code."

value = aws_s3_bucket.lambda_bucket.id

}

4. Define Variables

Create variables.tf:

variable "aws_region" {  
  description = "AWS region for all resources."  
  type    = string  
  default = "us-east-1"  
}

variable "aws_region" {

description = "AWS region for all resources."

type = string

default = "us-east-1"

}

5. Initialize and Apply Terraform

terraform init  
terraform apply --auto-approve

1 2	terraform init terraform apply --auto-approve

Task 2: Create and Upload Lambda Function Archive

1. Create a Node.js Lambda Function

mkdir hello-world &amp;&amp; cd hello-world

1	mkdir hello-world && cd hello-world

Create hello.js:

module.exports.handler = async (event) =&gt; {  
  console.log('Event: ', event);  
  let responseMessage = 'Hello, World!';  
  return {  
    statusCode: 200,  
    headers: {  
      'Content-Type': 'application/json',  
    },  
    body: JSON.stringify({  
      message: responseMessage,  
    }),  
  }  
}

module.exports.handler = async (event) => {

console.log('Event: ', event);

let responseMessage = 'Hello, World!';

return {

statusCode: 200,

headers: {

'Content-Type': 'application/json',

body: JSON.stringify({

message: responseMessage,

}),

}

2. Package and Upload the Function

Create s3_object.tf:

data "archive_file" "lambda_hello_world" {  
  type = "zip"  
  source_dir  = "${path.module}/hello-world"  
  output_path = "${path.module}/hello-world.zip"  
}  

resource "aws_s3_object" "lambda_hello_world" {  
  bucket = aws_s3_bucket.lambda_bucket.id  
  key    = "hello-world.zip"  
  source = data.archive_file.lambda_hello_world.output_path  
  etag = filemd5(data.archive_file.lambda_hello_world.output_path)  
}

data "archive_file" "lambda_hello_world" {

type = "zip"

source_dir = "${path.module}/hello-world"

output_path = "${path.module}/hello-world.zip"

}

resource "aws_s3_object" "lambda_hello_world" {

bucket = aws_s3_bucket.lambda_bucket.id

key = "hello-world.zip"

source = data.archive_file.lambda_hello_world.output_path

etag = filemd5(data.archive_file.lambda_hello_world.output_path)

}

3. Apply Configuration

terraform init -upgrade  
terraform apply --auto-approve

1 2	terraform init -upgrade terraform apply --auto-approve

Task 3: Create the Lambda Function

1. Define Lambda Function and IAM Role

Create lambda.tf:

resource "aws_lambda_function" "hello_world" {  
  function_name = "MeharHelloWorld"  
  s3_bucket = aws_s3_bucket.lambda_bucket.id  
  s3_key    = aws_s3_object.lambda_hello_world.key  
  runtime = "nodejs20.x"  
  handler = "hello.handler"  
  source_code_hash = data.archive_file.lambda_hello_world.output_base64sha256  
  role = aws_iam_role.lambda_exec.arn  
}  

resource "aws_cloudwatch_log_group" "hello_world" {  
  name = "/aws/lambda/${aws_lambda_function.hello_world.function_name}"  
  retention_in_days = 30  
}  

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

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

resource "aws_lambda_function" "hello_world" {

function_name = "MeharHelloWorld"

s3_bucket = aws_s3_bucket.lambda_bucket.id

s3_key = aws_s3_object.lambda_hello_world.key

runtime = "nodejs20.x"

handler = "hello.handler"

source_code_hash = data.archive_file.lambda_hello_world.output_base64sha256

role = aws_iam_role.lambda_exec.arn

}

resource "aws_cloudwatch_log_group" "hello_world" {

name = "/aws/lambda/${aws_lambda_function.hello_world.function_name}"

retention_in_days = 30

}

resource "aws_iam_role" "lambda_exec" {

name = "mehar-serverless_lambda"

assume_role_policy = jsonencode({

Version = "2012-10-17"

Statement = [{

Action = "sts:AssumeRole"

Effect = "Allow"

Sid = ""

Principal = {

Service = "lambda.amazonaws.com"

}

}]

})

}

resource "aws_iam_role_policy_attachment" "lambda_policy" {

role = aws_iam_role.lambda_exec.name

policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"

}

2. Add Lambda Output

Create outputs_lambda.tf:

output "function_name" {  
  description = "Name of the Lambda function."  
  value = aws_lambda_function.hello_world.function_name  
}

output "function_name" {

description = "Name of the Lambda function."

value = aws_lambda_function.hello_world.function_name

}

3. Apply and Test Lambda

terraform apply --auto-approve  
aws lambda invoke --region=us-east-1 --function-name=$(terraform output -raw function_name) response.json  
cat response.json

terraform apply --auto-approve

aws lambda invoke --region=us-east-1 --function-name=$(terraform output -raw function_name) response.json

cat response.json

Task 4: Create an HTTP API with API Gateway

1. Define API Gateway Resources

Create api.tf:

resource "aws_apigatewayv2_api" "lambda" {  
  name          = "mehar-serverless_lambda_gw"  
  protocol_type = "HTTP"  
}  

resource "aws_apigatewayv2_stage" "lambda" {  
  api_id = aws_apigatewayv2_api.lambda.id  
  name        = "mehar-serverless_lambda_stage"  
  auto_deploy = true  
  access_log_settings {  
    destination_arn = aws_cloudwatch_log_group.api_gw.arn  
    format = jsonencode({  
      requestId               = "$context.requestId"  
      sourceIp                = "$context.identity.sourceIp"  
      requestTime             = "$context.requestTime"  
      protocol                = "$context.protocol"  
      httpMethod              = "$context.httpMethod"  
      resourcePath            = "$context.resourcePath"  
      routeKey                = "$context.routeKey"  
      status                  = "$context.status"  
      responseLength          = "$context.responseLength"  
      integrationErrorMessage = "$context.integrationErrorMessage"  
    })  
  }  
}  

resource "aws_apigatewayv2_integration" "hello_world" {  
  api_id = aws_apigatewayv2_api.lambda.id  
  integration_uri    = aws_lambda_function.hello_world.invoke_arn  
  integration_type   = "AWS_PROXY"  
  integration_method = "POST"  
}  

resource "aws_apigatewayv2_route" "hello_world" {  
  api_id = aws_apigatewayv2_api.lambda.id  
  route_key = "GET /hello"  
  target    = "integrations/${aws_apigatewayv2_integration.hello_world.id}"  
}  

resource "aws_cloudwatch_log_group" "api_gw" {  
  name = "/aws/api_gw/${aws_apigatewayv2_api.lambda.name}"  
  retention_in_days = 30  
}  

resource "aws_lambda_permission" "api_gw" {  
  statement_id  = "AllowExecutionFromAPIGateway"  
  action        = "lambda:InvokeFunction"  
  function_name = aws_lambda_function.hello_world.function_name  
  principal     = "apigateway.amazonaws.com"  
  source_arn = "${aws_apigatewayv2_api.lambda.execution_arn}/*/*"  
}

resource "aws_apigatewayv2_api" "lambda" {

name = "mehar-serverless_lambda_gw"

protocol_type = "HTTP"

}

resource "aws_apigatewayv2_stage" "lambda" {

api_id = aws_apigatewayv2_api.lambda.id

name = "mehar-serverless_lambda_stage"

auto_deploy = true

access_log_settings {

destination_arn = aws_cloudwatch_log_group.api_gw.arn

format = jsonencode({

requestId = "$context.requestId"

sourceIp = "$context.identity.sourceIp"

requestTime = "$context.requestTime"

protocol = "$context.protocol"

httpMethod = "$context.httpMethod"

resourcePath = "$context.resourcePath"

routeKey = "$context.routeKey"

status = "$context.status"

responseLength = "$context.responseLength"

integrationErrorMessage = "$context.integrationErrorMessage"

})

}

resource "aws_apigatewayv2_integration" "hello_world" {

api_id = aws_apigatewayv2_api.lambda.id

integration_uri = aws_lambda_function.hello_world.invoke_arn

integration_type = "AWS_PROXY"

integration_method = "POST"

}

resource "aws_apigatewayv2_route" "hello_world" {

api_id = aws_apigatewayv2_api.lambda.id

route_key = "GET /hello"

target = "integrations/${aws_apigatewayv2_integration.hello_world.id}"

}

resource "aws_cloudwatch_log_group" "api_gw" {

name = "/aws/api_gw/${aws_apigatewayv2_api.lambda.name}"

retention_in_days = 30

}

resource "aws_lambda_permission" "api_gw" {

statement_id = "AllowExecutionFromAPIGateway"

action = "lambda:InvokeFunction"

function_name = aws_lambda_function.hello_world.function_name

principal = "apigateway.amazonaws.com"

source_arn = "${aws_apigatewayv2_api.lambda.execution_arn}/*/*"

}

2. Add API Output

Create outputs_api.tf:

output “base_url” {
description = “Base URL for API Gateway stage.”
value = aws_apigatewayv2_stage.lambda.invoke_url
}

3. Apply and Test API Gateway

terraform apply --auto-approve  
curl "$(terraform output -raw base_url)/hello"

1 2	terraform apply --auto-approve curl "$(terraform output -raw base_url)/hello"

Task 5: Clean Up Resources

terraform destroy --auto-approve  
cd ~ &amp;&amp; rm -rf serverless

1 2	terraform destroy --auto-approve cd ~ && rm -rf serverless

Conclusion

By following this guide, you have successfully deployed a serverless application using Terraform, integrating AWS Lambda, API Gateway, and S3. This setup ensures scalability, cost efficiency, and ease of management while eliminating the need for manual infrastructure handling.

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