What kind of Magic is this?

Imagine a world where setting up complex infrastructures is as easy as casting a spell.
That’s what this AWS CloudFormation template offers.
It’s a meticulously crafted magical scroll — configurable, reusable, and designed to conjure up a robust API Gateway connected to a Lambda function, all with minimal manual intervention.

What Does This Template Summon?

• API Gateway as the Front Gate:

  The face of your operations, it’s a custom domain API Gateway, easily configurable to represent your unique digital presence in the cloud.
  The template will create a Rest API with POST Method, A Resource, set up a Domain name and create a Prod Stage for deployment.

• Lambda, the Magic Worker:

  Behind this gateway lies the real wizardry.
  Ready to execute your business logic without the need to manage servers.
  The lambda is triggered by the above api gateway (any method it has) and the code that powers this function rests securely in an existing S3 bucket, summoned and executed as needed.
  

• The Invisible Cloak of Security:

  The template weaves an IAM role automatically, granting your Lambda function the precise permissions needed to perform its duties securely and efficiently.
  It can use the S3 code and write cloudwatch logs and metrics.

How It Works: The Spellbinding Process

Deploying this template is like weaving a spell.
You specify your configurations — like the domain name for your API Gateway or the S3 bucket for your Lambda code — and let the template do the rest.
It’s a seamless dance of resources, orchestrated by the template, resulting in a fully functional, scalable, and secure application endpoint, worker and security.

Prerequisites:

• An AWS account with administrative access.

• Your own custom domain name, configured with Route 53 or a third-party DNS provider.

• A signed ACM certificate (us-east)

• S3 bucket to hold the lambda code.

• Code repository files uploaded to the mentioned S3 bucket.

• A basic understanding of AWS Lambda functions and API Gateway configurations.

Lets Get Down to Business, How to Use the Template:

1. Set up the prerequisites.
2. Modify the Parameters at the top of the yaml.
3. Deploy the stack using aws console or aws cli.

Copy the template code to your own .yaml file.

AWSTemplateFormatVersion: 2010-09-09
Description: apigw-lambda-domain-iam API Gateway, Lambda function, custom domain, and base path mapping.

Parameters:
  ApiGatewayName: # API Gateway Name
    Type: String
    Default: ChatApi
  ApiGatewayHTTPMethod: # API Gateway HTTP Method to invoke the Lambda function
    Type: String
    Default: POST
  lambdaFunctionName: # Lambda Function Name
    Type: String
    AllowedPattern: '[a-zA-Z0-9]+[a-zA-Z0-9-]+[a-zA-Z0-9]+'
    Default: ServerlesSetupLambda
  CodeS3Bucket: # S3 Bucket Name ** should be set up before deploying the stack **
    Type: String
    Default: codereposbucket
  S3CodeFileName: # S3 Code File Name ** should be set up before deploying the stack **
    Type: String
    Default: lambdaCode.zip
  PathPart: # API Gateway Resource Path Part
    Type: String
    Default: chat
  DomainName: # Custom Domain Name
    Type: String
    Default: ai.asafmaoz.com
  CertificateArn: # SSL Certificate ARN us-east ** should be set up before deploying the stack **
    Type: String
    Default: arn:aws:acm:us-east-1:353012345243:certificate/123456-1df6-4a98-984c-4b321432f683
  LambdaHandler: # Lambda Handler
    Type: String
    Default: com.asafmaoz.LambdaExample
  LambdaRunTime: # Lambda Runtime
    Type: String
    Default: java11

Resources:
  ApiGatewayRestApi:
    Type: AWS::ApiGateway::RestApi
    Properties:
      Description: API Gateway RestApi
      Name: !Ref ApiGatewayName

  ApiGatewayMethod:
    Type: AWS::ApiGateway::Method
    Properties:
      AuthorizationType: NONE
      HttpMethod: !Ref ApiGatewayHTTPMethod
      ResourceId: !Ref ApiGatewayResource
      RestApiId: !Ref ApiGatewayRestApi
      Integration:
        IntegrationHttpMethod: POST
        Type: AWS_PROXY
        Uri: !Sub arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${LambdaFunction.Arn}/invocations
      MethodResponses:
        - StatusCode: 200

  ApiGatewayResource:
    Type: AWS::ApiGateway::Resource
    Properties:
      ParentId: !GetAtt ApiGatewayRestApi.RootResourceId
      PathPart: !Ref PathPart
      RestApiId: !Ref ApiGatewayRestApi

  ApiGatewayDeployment:
    Type: AWS::ApiGateway::Deployment
    Properties:
      RestApiId: !Ref ApiGatewayRestApi
    DependsOn:
      - ApiGatewayMethod

  ApiGatewayDomainName:
    Type: AWS::ApiGateway::DomainName
    Properties:
      RegionalCertificateArn: !Ref CertificateArn
      DomainName: !Ref DomainName
      EndpointConfiguration: # Endpoint Type for the API Gateway custom domain name
        Types:
          - REGIONAL

  ApiGatewayStage:
    Type: AWS::ApiGateway::Stage
    Properties:
      RestApiId: !Ref ApiGatewayRestApi
      DeploymentId: !Ref ApiGatewayDeployment
      StageName: Prod

  ApiGatewayBasePathMapping:
    Type: AWS::ApiGateway::BasePathMapping
    Properties:
      DomainName: !Ref ApiGatewayDomainName
      RestApiId: !Ref ApiGatewayRestApi
      Stage: Prod
    DependsOn:
      - ApiGatewayStage

  LambdaFunction:
    Type: AWS::Lambda::Function
    Properties:
      Handler: !Ref LambdaHandler
      Role: !GetAtt lambdaIAMRole.Arn
      FunctionName: !Ref lambdaFunctionName
      Code:
        S3Bucket: !Ref CodeS3Bucket
        S3Key: !Ref S3CodeFileName
      Runtime: !Ref LambdaRunTime

  LambdaInvokePermission:
    Type: AWS::Lambda::Permission
    Properties:
      Action: lambda:InvokeFunction
      FunctionName: !GetAtt LambdaFunction.Arn
      Principal: apigateway.amazonaws.com
      SourceArn: !Sub arn:aws:execute-api:${AWS::Region}:${AWS::AccountId}:${ApiGatewayRestApi}/*/${ApiGatewayHTTPMethod}/${PathPart}
    # Note: SourceArn here means any method on any resource within the API Gateway can invoke this Lambda.

  lambdaIAMRole:
    Type: AWS::IAM::Role
    Properties:
      AssumeRolePolicyDocument:
        Version: 2012-10-17
        Statement:
          - Action:
              - sts:AssumeRole
            Effect: Allow
            Principal:
              Service:
                - lambda.amazonaws.com
      Policies:
        - PolicyDocument:
            Version: 2012-10-17
            Statement:
              - Action:
                  - logs:CreateLogGroup
                  - logs:CreateLogStream
                  - logs:PutLogEvents
                Effect: Allow
                Resource:
                  - !Sub arn:aws:logs:${AWS::Region}:${AWS::AccountId}:log-group:/aws/lambda/${lambdaFunctionName}:*
          PolicyName: lambda

  lambdaLogGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: !Sub /aws/lambda/${lambdaFunctionName}
      RetentionInDays: 90

Outputs:
  ApiGatewayRestApi:
    Description: API Gateway RestApi
    Value: !Ref ApiGatewayRestApi

  ApiGatewayInvokeURL:
    Description: API Gateway Invoke URL
    Value: !Sub https://${ApiGatewayDomainName}/Prod/${PathPart}

  lambdaArn:
    Value: !GetAtt LambdaFunction.Arn

                                            

* Change the Parameters to match your needs.

Conclusion

For developers and DevOps engineers looking to elevate their cloud infrastructure with efficiency, security, and scalability, this CloudFormation template is your gateway to magic. It transforms complex cloud setups into a simple, magical process, letting you focus on what truly matters — creating incredible applications.

Harness the power of cloud magic today and watch as your serverless architecture takes flight, all with the wave of your magical CloudFormation wand!