Create delete_order Lambda function

In this step, we will create a new delete_order Lambda function using a SAM template.

Preparation

1. Open template.yaml in the source code you downloaded before.

   • Comment this code block.

     # BookApiDeployment:
     #   Type: AWS::ApiGateway::Deployment
     #   Properties:
     #     RestApiId: !Ref BookApi
     #   DependsOn:
     #     - BookApiGet
     #     - BookApiCreate
     #     - BookApiDelete
     #     - LoginApi
     #     - RegisterApi
     #     - ConfirmApi
     #     - FcjCheckoutOrderApi
     #     - FcjOrderManagementApi
     #     - FcjHandleOrderApi
     
     BookApiStage:
       Type: AWS::ApiGateway::Stage
       Properties:
         RestApiId: !Ref BookApi
         StageName: !Ref stage
     #     DeploymentId: !Ref BookApiDeployment
     

     

2. Run the below commands.

   sam build
   sam validate
   sam deploy
   

   

Create FcjDeleteOrder function

1. Open template.yaml in the source code you downloaded before.

   • Add the following scripts below to create FcjDeleteOrder function.

     FcjDeleteOrderFunction:
       Type: AWS::Serverless::Function
       Properties:
         CodeUri: fcj-book-shop/delete_order
         Handler: delete_order.lambda_handler
         Runtime: python3.11
         FunctionName: delete_order
         Environment:
           Variables:
             SQS_QUEUE_URL: !Ref checkoutQueueUrl
         Architectures:
           - x86_64
         Policies:
           - Statement:
               - Sid: VisualEditor0
                 Effect: Allow
                 Action:
                   - sqs:*
                 Resource:
                   - !Sub "arn:aws:sqs:${AWS::Region}:${AWS::AccountId}:${checkoutQueueName}"
     
     FcjDeleteOrderApi:
       Type: AWS::ApiGateway::Method
       Properties:
         HttpMethod: DELETE
         RestApiId: !Ref BookApi
         ResourceId: !Ref FcjCheckoutOrderResource
         AuthorizationType: NONE
         Integration:
           Type: AWS_PROXY
           IntegrationHttpMethod: POST # For Lambda integrations, you must set the integration method to POST
           Uri: !Sub >-
             arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${FcjDeleteOrderFunction.Arn}/invocations
         MethodResponses:
           - StatusCode: "200"
             ResponseParameters:
               method.response.header.Access-Control-Allow-Origin: true
               method.response.header.Access-Control-Allow-Methods: true
               method.response.header.Access-Control-Allow-Headers: true
     
     FcjDeleteOrderApiInvokePermission:
       Type: AWS::Lambda::Permission
       Properties:
         FunctionName: !Ref FcjDeleteOrderFunction
         Action: lambda:InvokeFunction
         Principal: apigateway.amazonaws.com
         SourceAccount: !Ref "AWS::AccountId"
     

     

2. The directory structure is as follows.

   fcj-book-shop-sam-ws3
   ├── fcj-book-shop
   │   ├── checkout_order
   │   │   └── checkout_order.py
   │   ├── order_management
   │   │   └── order_management.py
   │   ├── handle_order
   │   │   └── handle_order.py
   │   ├── delete_order
   │   │   └── delete_order.py
   │   ├── ...
   │
   └── template.yaml
   

   • Create delete_order folder in fcj-book-shop-sam-ws6/fcj-book-shop/ folder.

   • Create delete_order.py file and copy the following code to it.

     import json
     import boto3
     import os
     
     headers = {
         "Content-Type": "application/json",
         "Access-Control-Allow-Origin": "*",
         "Access-Control-Allow-Methods": "OPTIONS,POST,GET,DELETE",
         "Access-Control-Allow-Headers": "Content-Type,X-Amz-Date,Authorization,X-Api-Key,X-Amz-Security-Token"
     }
     
     sqs = boto3.client('sqs')
     
     # Get value of the environment variables
     queue_url = os.getenv('SQS_QUEUE_URL')
     
     
     def lambda_handler(event, context):
         order = json.loads(event['body'])
     
         try:
             if 'receiptHandle' in order and order['receiptHandle']:
                 sqs.delete_message(
                     QueueUrl=queue_url,
                     ReceiptHandle=order['receiptHandle']
                 )
     
             else:
                 raise Exception("No receiptHandle provided")
     
         except Exception as e:
             print(f"Error deleting order: {e}")
             raise Exception(f"Error deleting order: {e}")
     
         return {
             'statusCode': 200,
             'headers': headers,
             'body': json.dumps('Order deleted successfully')
         }
     

     

3. Uncomment this code block.

   BookApiDeployment:
     Type: AWS::ApiGateway::Deployment
     Properties:
       RestApiId: !Ref BookApi
     DependsOn:
       - BookApiGet
       - BookApiCreate
       - BookApiDelete
       - LoginApi
       - RegisterApi
       - ConfirmApi
       - FcjCheckoutOrderApi
       - FcjOrderManagementApi
       - FcjHandleOrderApi
       - FcjDeleteOrderApi
   
   BookApiStage:
     Type: AWS::ApiGateway::Stage
     Properties:
       RestApiId: !Ref BookApi
       StageName: !Ref stage
       DeploymentId: !Ref BookApiDeployment
   

   

4. Run the below commands.

   sam build
   sam validate
   sam deploy
   

   

Check the creation

1. Open Amazon API Gateway console.

   • Click fcj-serverless-api.
   • Click Resources on the left menu.
   • Check /order just created.

2. Open Amazon Lambda console.

   • Click Functions on the left menu.
   • Choose delete_order function.
   • At delete_order page, check the function that just created.