How to Deploy a Serverless Application on AWS Using Terraform

In today's fast-paced tech landscape, serverless architectures have taken center stage, allowing developers to focus on writing code without the hassle of managing servers. Amazon Web Services (AWS) offers a robust platform for serverless applications, and Terraform, an Infrastructure as Code (IaC) tool, provides a powerful way to manage and provision your serverless infrastructure. This article will guide you through deploying a serverless application on AWS using Terraform, complete with definitions, use cases, step-by-step instructions, and code snippets.

What is Serverless Computing?

Before diving into the deployment process, let's clarify what serverless computing is. Contrary to its name, serverless computing does not mean there are no servers involved; rather, it abstracts the server management away from the developer. Key benefits include:

• Cost efficiency: Pay only for the resources you consume.
• Scalability: Automatically scales based on demand.
• Reduced operational overhead: Focus on code rather than infrastructure.

Why Use AWS for Serverless Applications?

AWS Lambda is Amazon's serverless computing service that allows you to run code without provisioning or managing servers. It supports various programming languages and integrates seamlessly with other AWS services, making it an ideal choice for building scalable applications.

Use Cases for Serverless Applications

• Web Applications: Host dynamic websites with minimal infrastructure management.
• APIs: Build RESTful APIs using AWS Lambda and API Gateway.
• Data Processing: Automate data workflows without the need for dedicated servers.

Setting Up Your Environment

Prerequisites

Before we start deploying, ensure you have the following:

• An AWS account
• Terraform installed on your local machine
• AWS CLI configured with the necessary permissions

You can install Terraform by following the instructions on the official Terraform website.

Step-by-Step Guide to Deploy a Serverless Application

Step 1: Create a New Terraform Project

First, create a directory for your Terraform project:

mkdir my-serverless-app
cd my-serverless-app

Step 2: Define Your Terraform Configuration

Create a main.tf file in your project directory. This file will contain your Terraform configuration.

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

resource "aws_lambda_function" "my_function" {
  function_name = "myServerlessFunction"
  runtime       = "nodejs14.x"
  role          = aws_iam_role.lambda_exec.arn
  handler       = "index.handler"

  source_code_hash = filebase64sha256("function.zip")

  filename         = "function.zip"
}

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

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

resource "aws_iam_policy_attachment" "lambda_exec" {
  name       = "lambda_exec_policy_attachment"
  roles      = [aws_iam_role.lambda_exec.name]
  policies   = ["service-role/AWSLambdaBasicExecutionRole"]
}

Step 3: Write Your Lambda Function

Create an index.js file in the same directory with the following sample code:

exports.handler = async (event) => {
    console.log("Event: ", event);
    return {
        statusCode: 200,
        body: JSON.stringify('Hello from Lambda!'),
    };
};

Step 4: Package Your Lambda Function

You need to package your Lambda function into a zip file. Run the following command:

zip function.zip index.js

Step 5: Initialize Terraform

Initialize your Terraform project to download the necessary providers:

terraform init

Step 6: Validate Your Configuration

Before applying your changes, validate your Terraform configuration:

terraform validate

Step 7: Deploy Your Application

Now, it’s time to deploy your serverless application:

terraform apply

Terraform will show you a plan of what it will create. Type yes to proceed with the deployment.

Step 8: Test Your Lambda Function

Once your function is deployed, you can test it using the AWS Management Console or via the AWS CLI. To invoke your function, use the following command:

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

Check output.txt for the response.

Troubleshooting Common Issues

1. Permission Denied Errors

If you encounter permission errors, ensure that your IAM role has the necessary permissions to execute the Lambda function.

2. Code Not Updating

If the code changes are not reflected, ensure you update the zip file with your latest code and re-run the terraform apply command.

Conclusion

Deploying a serverless application on AWS using Terraform is a straightforward process that can save you time and resources. By following the steps outlined in this article, you can leverage the power of serverless computing while managing your infrastructure as code.

Embrace the future of application deployment with serverless architectures and the flexibility of Terraform, and watch as your development process becomes more efficient and scalable. Happy coding!