8-deploying-a-serverless-application-using-aws-lambda-and-terraform.html

Deploying a Serverless Application Using AWS Lambda and Terraform

In today's fast-paced digital landscape, businesses are increasingly turning to serverless architectures to optimize their application deployment and management. AWS Lambda, Amazon's serverless compute service, allows you to run code without provisioning or managing servers. When combined with Terraform, an Infrastructure as Code (IaC) tool, you can automate the deployment and management of your serverless applications efficiently. In this article, we’ll explore how to deploy a serverless application using AWS Lambda and Terraform, providing clear code examples and actionable insights along the way.

What is AWS Lambda?

AWS Lambda is a serverless computing service that lets you run code in response to events without managing servers. You can execute code for virtually any type of application or backend service, all with zero administration. Lambda automatically scales your application by running code in parallel and only charging for the compute time consumed.

Key Benefits of AWS Lambda

Cost Efficiency: You pay only for the compute time you consume.
Automatic Scaling: Lambda scales automatically by running your code in response to incoming requests.
Integrated with AWS Ecosystem: It seamlessly integrates with other AWS services like S3, DynamoDB, API Gateway, and more.

What is Terraform?

Terraform is an open-source IaC tool that allows you to define your infrastructure using a high-level configuration language. With Terraform, you can create, manage, and provision resources across different cloud providers, including AWS.

Key Features of Terraform

Declarative Configuration: Define your infrastructure in configuration files.
Resource Management: Manage dependencies and changes to your infrastructure easily.
Multi-Provider Support: Work with multiple cloud providers and services.

Use Case: Building a Serverless REST API

In this tutorial, we will create a simple serverless REST API using AWS Lambda and Terraform. The API will respond to HTTP requests and return a JSON response. We'll break down the deployment into manageable steps.

Prerequisites

An AWS account.
Terraform installed on your machine.
AWS CLI configured with your credentials.

Step 1: Setting Up Your Terraform Project

First, create a new directory for your project:

mkdir serverless-api
cd serverless-api

Create a file named main.tf in your project directory. This file will contain the configuration for your AWS resources.

provider "aws" {
  region = "us-east-1"
}

resource "aws_lambda_function" "hello" {
  function_name = "HelloWorldFunction"
  handler       = "hello.handler"
  runtime       = "nodejs14.x"
  role          = aws_iam_role.lambda_exec.arn

  source_code_hash = filebase64sha256("hello.zip")

  environment {
    MESSAGE = "Hello, World!"
  }
}

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

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

resource "aws_lambda_permission" "allow_api_gateway" {
  statement_id  = "AllowExecutionFromAPIGateway"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.hello.function_name
  principal     = "apigateway.amazonaws.com"
}

resource "aws_api_gateway_rest_api" "api" {
  name        = "HelloWorldAPI"
  description = "API for Hello World"
}

resource "aws_api_gateway_resource" "hello" {
  rest_api_id = aws_api_gateway_rest_api.api.id
  parent_id   = aws_api_gateway_rest_api.api.root_resource_id
  path_part   = "hello"
}

resource "aws_api_gateway_method" "get_hello" {
  rest_api_id   = aws_api_gateway_rest_api.api.id
  resource_id   = aws_api_gateway_resource.hello.id
  http_method   = "GET"
  authorization = "NONE"
}

resource "aws_api_gateway_integration" "hello_integration" {
  rest_api_id             = aws_api_gateway_rest_api.api.id
  resource_id             = aws_api_gateway_resource.hello.id
  http_method             = aws_api_gateway_method.get_hello.http_method
  integration_http_method = "POST"
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.hello.invoke_arn
}

resource "aws_api_gateway_deployment" "deployment" {
  rest_api_id = aws_api_gateway_rest_api.api.id
  stage_name  = "prod"
}

Explanation of Code

Provider Block: Defines the AWS provider and region.
Lambda Function: Creates a Lambda function that returns a "Hello, World!" message.
IAM Role: Sets up an IAM role with permissions for Lambda execution.
API Gateway Resources: Configures API Gateway to route requests to the Lambda function.

Step 2: Creating Your Lambda Function Code

Next, create a simple Lambda function. Create a file named hello.js in your project directory:

exports.handler = async (event) => {
  const message = process.env.MESSAGE;
  return {
    statusCode: 200,
    body: JSON.stringify({ message }),
  };
};

Package Your Code

To deploy the Lambda function, you need to zip your code:

zip hello.zip hello.js

Step 3: Deploying with Terraform

Now, initialize Terraform and deploy your resources:

terraform init
terraform apply

You will see a prompt to confirm the deployment. Type yes to proceed.

Step 4: Testing Your API

After the deployment, you can find the API endpoint in the output of the terraform apply command. Test your API using curl:

curl https://<api-id>.execute-api.us-east-1.amazonaws.com/prod/hello

You should receive a JSON response:

{"message":"Hello, World!"}

Step 5: Troubleshooting Tips

If you encounter issues, consider the following:

Check IAM Roles: Ensure your Lambda function has the correct permissions.
Review Logs: Use AWS CloudWatch to check logs for errors.
Validate Terraform Configuration: Run terraform plan to see the planned changes.

Conclusion

Deploying a serverless application using AWS Lambda and Terraform is an efficient way to scale your application while minimizing overhead. By leveraging the power of IaC, you can automate your deployments, manage configurations, and maintain a clean infrastructure. With the steps outlined in this article, you should be well-equipped to create your serverless REST API and expand your cloud computing skills. Happy coding!