Create GET API

In this step, we will add the GET method to our REST API so that the frontend can retrieve the list of books from the books_list Lambda function. We will also create the API deployment and a staging stage to make the endpoint accessible via a public URL.

Edit SAM Template

1. Open the template.yaml file in the fcaj-book-shop folder.

2. Add the stage parameter under the Parameters section. This controls which deployment stage name is used:

   stage:
     Type: String
     Default: staging
   

   

3. Add the following resources under the Resources section to create the GET method and its deployment:

   BookApiGet:
     Type: AWS::ApiGateway::Method
     Properties:
       HttpMethod: GET
       RestApiId: !Ref BookApi
       ResourceId: !Ref BookApiResource
       AuthorizationType: NONE
       Integration:
         Type: AWS_PROXY
         IntegrationHttpMethod: POST # For Lambda integrations, you must set the integration method to POST
         Uri: !Sub >-
           arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${BooksList.Arn}/invocations
         IntegrationResponses:
           - StatusCode: "200"
             ResponseParameters:
               method.response.header.Access-Control-Allow-Origin: "'*'"
               method.response.header.Access-Control-Allow-Methods: "'GET,POST,OPTIONS'"
               method.response.header.Access-Control-Allow-Headers: "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token'"
       MethodResponses:
         - StatusCode: "200"
           ResponseParameters:
             method.response.header.Access-Control-Allow-Origin: "'*'"
             method.response.header.Access-Control-Allow-Methods: "'GET,POST,OPTIONS'"
             method.response.header.Access-Control-Allow-Headers: "'Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token'"
   
   BookApiDeployment:
     Type: AWS::ApiGateway::Deployment
     Properties:
       RestApiId: !Ref BookApi
     DependsOn:
       - BookApiGet
   

   

4. Continue adding the stage and invoke permission resources right after BookApiDeployment:

   BookApiStage:
     Type: AWS::ApiGateway::Stage
     Properties:
       RestApiId: !Ref BookApi
       StageName: !Ref stage
       DeploymentId: !Ref BookApiDeployment
   
   BookApiGetInvokePermission:
     Type: AWS::Lambda::Permission
     Properties:
       FunctionName: !Ref BooksList
       Action: lambda:InvokeFunction
       Principal: apigateway.amazonaws.com
       SourceAccount: !Ref "AWS::AccountId"
   

   

Build and Deploy

5. Run the following commands to validate and build the SAM template:

   sam validate
   sam build
   

   

6. Deploy the updated stack:

   sam deploy
   

   The changeset will show the following new resources being added:

   • BookApiGet (AWS::ApiGateway::Method)
   • BookApiDeployment (AWS::ApiGateway::Deployment)
   • BookApiStage (AWS::ApiGateway::Stage)
   • BookApiGetInvokePermission (AWS::Lambda::Permission)

   Enter y to confirm the deployment.

   

7. Wait for the deployment to complete. You should see Successfully created/updated stack - fcaj-book-shop in ap-southeast-1.

   

Verify on AWS Console

8. Open the AWS API Gateway console. Click on the fcaj-serverless-api REST API.

   

9. At the fcaj-serverless-api page:

   • Click Resources in the left menu.
   • Select GET under the /books resource.
   • Click the Lambda integration tooltip on the right side of the method execution diagram — confirm the integrated function is books_list.

   

10. Click Stages in the left menu.

    • Expand the staging stage → /books → select GET.
    • Copy and save the Invoke URL — you will need it to configure the frontend.

    Example: https://1bupjnr42d.execute-api.ap-southeast-1.amazonaws.com/staging/books