What are the steps to build and deploy a serverless application using AWS SAM?

August 30, 2024

In today’s rapidly evolving digital landscape, serverless applications have become a game-changer. They not only simplify the development process but also optimize resource utilization. AWS SAM (Serverless Application Model) is a tool that enables you to build, test, and deploy serverless applications effortlessly. This article will guide you through the specific steps to build and deploy a serverless application using AWS SAM, ensuring you leverage the power of AWS effectively.

Understanding AWS SAM

Before diving into the step-by-step process, it’s essential to understand what AWS SAM is. AWS SAM is an open-source framework that extends AWS CloudFormation to provide a simplified way to define your serverless applications. It includes shorthand syntax to express functions, APIs, databases, and event source mappings. By using SAM, you can define your serverless application as a single configuration file and deploy it swiftly.

Setting Up Your Development Environment

To start building and deploying a serverless application with AWS SAM, you need to set up your development environment. This involves installing the necessary tools, configuring your AWS account, and preparing your project.

Installing AWS SAM CLI

First, you need to install the AWS SAM CLI (Command Line Interface). The SAM CLI helps you locally build, test, and debug your serverless applications defined by AWS SAM templates. You can install the SAM CLI by following these steps:

Download and Install: Visit the AWS SAM CLI installation page and follow the instructions for your operating system.
Verify Installation: Open your terminal and run sam --version to ensure the installation was successful.

Configuring AWS Credentials

Next, configure your AWS credentials using the AWS CLI. This allows the SAM CLI to interact with your AWS account. Run the following command and enter your AWS credentials:

aws configure

You’ll be prompted to enter your AWS Access Key ID, Secret Access Key, Region, and Output format.

Setting Up Your Project

After installing the SAM CLI and configuring your AWS credentials, you can set up your project. Use the SAM CLI to create a new serverless application:

sam init

Follow the prompts to select the runtime (e.g., Python, Node.js) and the template for your application. This command creates a new project with the necessary files and folders, including a template.yaml file, which defines your application.

Writing Your Serverless Application Code

With the project set up, it’s time to write the code for your serverless application. This involves defining your AWS Lambda functions, configuring event sources, and adding any additional resources your application requires.

Defining Lambda Functions

AWS Lambda is a serverless compute service that lets you run code without provisioning or managing servers. In your SAM template (template.yaml), define your Lambda functions using the AWS::Serverless::Function resource type. Here’s an example:

Resources:
  MyFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: app.lambdaHandler
      Runtime: nodejs14.x
      CodeUri: src/
      Events:
        ApiEvent:
          Type: Api
          Properties:
            Path: /hello
            Method: get

In this example, MyFunction is a Lambda function triggered by an API Gateway event. The Handler specifies the entry point for your Lambda function, and CodeUri points to the directory containing your function code.

Configuring Event Sources

AWS SAM supports various event sources, such as API Gateway, S3, and DynamoDB. In the example above, we configured an API Gateway event that triggers the Lambda function when an HTTP GET request is made to the /hello path.

Adding Additional Resources

You might need other AWS resources for your application, such as DynamoDB tables, S3 buckets, or IAM roles. You can define these resources in your SAM template using standard CloudFormation resource types. For example, to add a DynamoDB table:

Resources:
  MyTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: MyTable
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      BillingMode: PAY_PER_REQUEST

This YAML snippet adds a DynamoDB table named MyTable with a primary key of id.

Building and Testing Your Application

After writing your code and defining your resources, the next step is to build and test your application. The SAM CLI provides commands to build your application locally and simulate the AWS environment for testing.

Building Your Application

Run the following command to build your application:

sam build

The sam build command packages your function dependencies and generates deployment artifacts. This step ensures that your application is ready for deployment.

Testing Locally

To test your Lambda functions locally, use the sam local commands. For example, to invoke a function locally:

sam local invoke MyFunction

This command runs your Lambda function in a local environment, allowing you to debug and test your code before deploying it to AWS.

Running NodeJSNPMBuilder

If you are using Node.js, ensure you run npm install within the directory of your Lambda function to install necessary dependencies. This step can be automated within the build process using SAM:

sam build --use-container

This command utilizes the NodeJSNPMBuilder to handle dependencies efficiently.

Deploying Your Serverless Application

Once your application is built and tested, you can deploy it to AWS using the SAM CLI. Deployment involves packaging your application, creating a CloudFormation stack, and deploying the stack to AWS.

Packaging Your Application

Run the following command to package your application:

sam package --output-template-file packaged.yaml --s3-bucket your-s3-bucket

This command packages your application and uploads the artifacts to an S3 bucket. It generates a packaged.yaml file that references the S3 locations of your deployment artifacts.

Deploying to AWS

Finally, deploy your packaged application to AWS:

sam deploy --template-file packaged.yaml --stack-name my-stack --capabilities CAPABILITY_IAM

The sam deploy command creates or updates a CloudFormation stack with the resources defined in your SAM template. The --capabilities CAPABILITY_IAM flag grants the necessary permissions to create IAM roles and policies.

Monitoring Progress

You can monitor the progress of your deployment using the AWS CloudFormation console. Navigate to the CloudFormation page in the AWS Management Console, and you will see the status of your stack. Successful deployment will have the status CREATE_COMPLETE or UPDATE_COMPLETE.

Building and deploying a serverless application using AWS SAM involves a series of well-defined steps. From setting up your development environment and writing your application code to building, testing, and finally deploying your application, AWS SAM simplifies the entire process. By leveraging the power of AWS Lambda, API Gateway, and other AWS services, you can deploy scalable and cost-effective serverless applications with ease.

With the right tools and a clear understanding of the steps involved, you are well-equipped to harness the potential of serverless technology. Whether you are a seasoned developer or just starting your journey, AWS SAM provides a robust framework to streamline the development and deployment of your serverless applications. Embrace the serverless paradigm and take your applications to new heights with AWS SAM.