Using Lambda with infrastructure as code (IaC)

Lambda offers several ways to deploy your code and create functions. For instance, you can use the Lambda console or the Amazon Command Line Interface (Amazon CLI) to manually create or update Lambda functions. In addition to these manual options, Amazon offers a number of solutions for deploying Lambda functions and serverless applications using infrastructure as code (IaC). With IaC, you can provision and maintain Lambda functions and other Amazon resources using code instead of using manual processes and settings.

Most of the time, Lambda functions don’t run in isolation. Instead, they form part of a serverless application with other resources such as databases, queues, and storage. With IaC, you can automate your deployment processes to quickly and repeatably deploy and update whole serverless applications involving many separate Amazon resources. This approach speeds up your development cycle, makes configuration management easier, and ensures that your resources are deployed the same way every time.

IaC tools for Lambda

To deploy Lambda functions and serverless applications using IaC, Amazon offers a number of different tools and services.

Amazon CloudFormation was the first service offered by Amazon to create and configure cloud resources. With Amazon CloudFormation, you create text templates to define infrastructure and code. As Amazon introduced more new services and the complexity of creating Amazon CloudFormation templates increased, two further tools were released. Amazon SAM is another template-based framework for defining serverless applications. The Amazon Cloud Development Kit (Amazon CDK) is a code-first approach for defining and provisioning infrastructure using code constructs in many popular programming languages.

With both Amazon SAM and the Amazon CDK, Amazon CloudFormation operates behind the scenes to build and deploy your infrastructure. The following diagram illustrates the relationship between these tools, and the paragraphs after the diagram explain their key features.

Amazon also provides a service called Amazon Application Composer to develop IaC templates using a simple graphical interface. With Application Composer, you design an application architecture by dragging, grouping, and connecting Amazon Web Services in a visual canvas. Application Composer then creates an Amazon SAM template or an Amazon CloudFormation template from your design that you can use to deploy your application.

In the Getting started with IaC for Lambda section below, you use Application Composer to develop a template for a serverless application based on an existing Lambda function.

Getting started with IaC for Lambda

In this tutorial, you can get started using IaC with Lambda by creating an Amazon SAM template from an existing Lambda function and then building out a serverless application in Application Composer by adding other Amazon resources.

If you'd rather start by carrying out an Amazon SAM or Amazon CloudFormation tutorial to learn how to work with templates without using Application Composer, you'll find links to other resources in the Next steps section at the end of this page.

As you carry out this tutorial, you’ll learn some fundamental concepts, like how Amazon resources are specified in Amazon SAM. You’ll also learn how to use Application Composer to build a serverless application you can deploy using Amazon SAM or Amazon CloudFormation.

To complete this tutorial, you’ll carry out the following steps:

In the Next steps section, you’ll find resources you can use to learn more about Amazon SAM and Application Composer. These resources include links to more advanced tutorials that teach you how to deploy a serverless application using Amazon SAM.

Prerequisites

In this tutorial, you use Application Composer’s local sync feature to save your template and code files to your local build machine. To use this feature, you need a browser that supports the File System Access API, which allows web applications to read, write, and save files in your local file system . We recommend using either Google Chrome or Microsoft Edge. For more information about the File System Access API, see What is the File System Access API?

Create a Lambda function

In this first step, you create a Lambda function you can use to complete the rest of the tutorial. To keep things simple, you use the Lambda console to create a basic 'Hello world' function using the Python 3.11 runtime.

View the Amazon SAM template for your function

Before you export your function configuration to Application Composer, use the Lambda console to view your function's current configuration as an Amazon SAM template. By following the steps in this section, you'll learn about the anatomy of an Amazon SAM template and how to define resources like Lambda functions to start specifying a serverless application.

Let’s take a moment to look at the YAML template for your function and understand some key concepts.

The template starts with the declaration Transform: AWS::Serverless-2016-10-31. This declaration is required because behind the scenes, Amazon SAM templates are deployed through Amazon CloudFormation. Using the Transform statement identifies the template as an Amazon SAM template file.

Following the Transform declaration comes the Resources section. This is where the Amazon resources you want to deploy with your Amazon SAM template are defined. Amazon SAM templates can contain a combination of Amazon SAM resources and Amazon CloudFormation resources. This is because during deployment, Amazon SAM templates expand to Amazon CloudFormation templates, so any valid Amazon CloudFormation syntax can be added to an Amazon SAM template.

At the moment, there is just one resource defined in the Resources section of the template, your Lambda function LambdaIaCDemo. To add a Lambda function to an Amazon SAM template, you use the AWS::Serverless::Function resource type. The Properties of a Lambda function resource define the function’s runtime, function handler, and other configuration options. The path to your function’s source code that Amazon SAM should use to deploy the function is also defined here. To learn more about Lambda function resources in Amazon SAM, see AWS::Serverless::Function in the Amazon SAM Developer Guide.

As well as the function properties and configurations, the template also specifies an Amazon Identity and Access Management (IAM) policy for your function. This policy gives your function permission to write logs to Amazon CloudWatch Logs. When you create a function in the Lambda console, Lambda automatically attaches this policy to your function. To learn more about specifying an IAM policy for a function in an Amazon SAM template, see the policies property on the AWS::Serverless::Function page of the Amazon SAM Developer Guide.

To learn more about the structure of Amazon SAM templates, see Amazon SAM template anatomy.

Use Amazon Application Composer to design a serverless application

To start building out a simple serverless application using your function’s Amazon SAM template as a starting point, you export your function configuration to Application Composer and activate Application Composer’s local sync mode. Local sync automatically saves your function’s code and your Amazon SAM template to your local build machine and keeps your saved template synced as you add other Amazon resources in Application Composer.

To export your function to Application Composer, you need permission to use certain API actions. If you're unable to export your function, see Required permissions and make sure you have the permissions you need.

Now that you’ve added these extra resources, let’s take a look at the updated Amazon SAM template Application Composer has created.

Your Amazon SAM template should now contain the following additional resources and properties:

The complete final Amazon SAM template should look like the following.

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: An AWS Serverless Specification template describing your function.
Resources:
  LambdaIaCDemo:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: .
      Description: ''
      MemorySize: 128
      Timeout: 3
      Handler: lambda_function.lambda_handler
      Runtime: python3.11
      Architectures:
        - x86_64
      EventInvokeConfig:
        MaximumEventAgeInSeconds: 21600
        MaximumRetryAttempts: 2
      EphemeralStorage:
        Size: 512
      RuntimeManagementConfig:
        UpdateRuntimeOn: Auto
      SnapStart:
        ApplyOn: None
      PackageType: Zip
      Policies:
        - Statement:
            - Effect: Allow
              Action:
                - logs:CreateLogGroup
              Resource: arn:aws:logs:us-east-1:594035263019:*
            - Effect: Allow
              Action:
                - logs:CreateLogStream
                - logs:PutLogEvents
              Resource:
                - arn:aws:logs:us-east-1:594035263019:log-group:/aws/lambda/LambdaIaCDemo:*
        - DynamoDBCrudPolicy:
            TableName: !Ref LambdaIaCTable
      Events:
        LambdaIaCQueue:
          Type: SQS
          Properties:
            Queue: !GetAtt LambdaIaCQueue.Arn
            BatchSize: 1
      Environment:
        Variables:
          LAMBDAIACTABLE_TABLE_NAME: !Ref LambdaIaCTable
          LAMBDAIACTABLE_TABLE_ARN: !GetAtt LambdaIaCTable.Arn
  LambdaIaCQueue:
    Type: AWS::SQS::Queue
    Properties:
      MessageRetentionPeriod: 345600
  LambdaIaCTable:
    Type: AWS::DynamoDB::Table
    Properties:
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      BillingMode: PAY_PER_REQUEST
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      StreamSpecification:
        StreamViewType: NEW_AND_OLD_IMAGES

Deploy your serverless application using Amazon SAM (optional)

If you want to use Amazon SAM to deploy a serverless application using the template you just created in Application Composer, you first need to install the Amazon SAM CLI. To do this, follow the instructions in Installing the Amazon SAM CLI.

Before you deploy your application, you also need to update the function code that Application Composer saved along with your template. At the moment, the lambda_function.py file that Application Composer saved contains only the basic 'Hello world' code that Lambda provided when you created the function.

To update your function code, copy the following code and paste it into the lambda_function.py file Application Composer saved to your local build machine. You specified the directory for Application Composer to save this file to when you activated Local Sync mode.

This code accepts a key value pair in a message from the Amazon SQS queue you created in Application Composer. If both the key and value are strings, the code then uses them to write an item to the DynamoDB table defined in your template.

import boto3
import os
import json

# define the DynamoDB table that Lambda will connect to
tablename = os.environ['LAMBDAIACTABLE_TABLE_NAME']

# create the DynamoDB resource
dynamo = boto3.client('dynamodb')

def lambda_handler(event, context):
    # get the message out of the SQS event
    message = event['Records'][0]['body']
    data = json.loads(message)
    # write event data to DDB table
    if check_message_format(data):
        key = next(iter(data))
        value = data[key]
        dynamo.put_item(
            TableName=tablename,
            Item={
                'id': {'S': key},
                'Value': {'S': value}
            }
        )
    else:
        raise ValueError("Input data not in the correct format")

# check that the event object contains a single key value  
# pair that can be written to the database
def check_message_format(message):
    if len(message) != 1:
        return False
        
    key, value = next(iter(message.items()))
    
    if not (isinstance(key, str) and isinstance(value, str)):
        return False

    else:
        return True

During the deployment process, Amazon SAM creates the following resources in your Amazon Web Services account:

Amazon SAM also creates the necessary IAM roles and policies so that your Lambda function can read messages from the Amazon SQS queue and perform CRUD operations on the DynamoDB table.

To learn more about using Amazon SAM to deploy serverless applications, see the resources in the Next steps section.

Testing your deployed application (optional)

To confirm that your serverless application deployed correctly, send a message to your Amazon SQS queue containing a key value pair and check that Lambda writes an item into your DynamoDB table using these values.

Next steps

To learn more about using Application Composer with Amazon SAM and Amazon CloudFormation, start with Using Application Composer with Amazon CloudFormation and Amazon SAM.

For a guided tutorial that uses Amazon SAM to deploy a serverless application designed in Application Composer, we also recommend you carry out the Amazon Application Composer tutorial in the Amazon Serverless Patterns Workshop.

Amazon SAM provides a command line interface (CLI) that you can use with Amazon SAM templates and supported third-party integrations to build and run your serverless applications. With the Amazon SAM CLI, you can build and deploy your application, perform local testing and debugging, configure CI/CD pipelines, and more. To learn more about using the Amazon SAM CLI, see Getting started with Amazon SAM in the Amazon Serverless Application Model Developer Guide.

To learn how to deploy a serverless application with an Amazon SAM template using the Amazon CloudFormation console, start with Using the Amazon CloudFormation console in the Amazon CloudFormation User Guide.

Supported regions for Lambda integration with Application Composer

Lambda integration with Application Composer is supported in the following Amazon Web Services Regions: