Resizing image Lmabda function

In this step we create a new Lambda function that resizes the image after the user uploads it.

  1. Open template.yaml file in fcj-book-shop folder
  2. Add the following script at the end of the file to create resizing image function 
    ImageResizer:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: fcj-book-shop/resize_image/function.zip
      PackageType: Zip
      Handler: index.handler
      Runtime: nodejs16.x
      FunctionName: resize_image
      Architectures:
        - x86_64
      Policies:
        - Statement:
            - Sid: ResizeUploadImage
              Effect: Allow
              Action:
                - s3:GetObject
                - s3:PutObject
                - s3:DeleteObject
              Resource:
                - arn:aws:s3:::book-image-shop/*
                - arn:aws:s3:::book-image-resize-shop/*
      Events:
        ResizeImage:
          Type: S3
          Properties:
            Bucket: !Ref BookImageShop
            Events: s3:ObjectCreated:*
      Environment:
        Variables:
          WIDTH: 200
          HEIGHT: 280
          DES_BUCKET: book-image-resize-shop

If you create S3 bucket names that are different from the ones in the lab, please check Policies | Resources or Environment of resources and update.

  • Add the following script at the end of the file to grant permission to the books-image-shop bucket to use this function

    LambdaInvokePermission:
    Type: "AWS::Lambda::Permission"
    Properties:
      FunctionName: !GetAtt ImageResizer.Arn
      Action: "lambda:InvokeFunction"
      Principal: "s3.amazonaws.com"
      SourceAccount: !Sub ${AWS::AccountId}
      SourceArn: !GetAtt BookImageShop.Arn

    LambdaDeleteFunction

  1. The directory structure is as follows:

    fcj-book-shop
├── fcj-book-shop
│   ├── books_list
│   │   └── books_list.py
│   ├── book_create
│   │   └── book_create.py
│   ├── book_delete
│   │   └── book_delete.py
│   ├── resize_image
│       └── function.zip
└── template.yaml
    • Create resize_image folder in fcj-book-shop/fcj-book-shop/ folder
    • Download the below file and copy to this folder
  2. function.zip (8382 ko)

  3. Run the following command to deploy SAM

    sam build
sam deploy

    LambdaDeleteFunction

  4. Back to Lambda console

    • Click resize_image function created LambdaDeleteFunction

  5. Click Configuration tab

    • Select Trigger on the left menu, display S3 bucket - book-image-shop

  6. Select Permissions on the left menu

    • Click on the role that the function is executing LambdaDeleteFunction

  7. Expand the policy, see the permissions granted to the function LambdaDeleteFunction