Resizing image Lambda 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.

    • Firstly, we will create width and height parameters.

      width:
  Type: String
  Default: 200px

height:
  Type: String
  Default: 280px

      LambdaResizeFunction

    • Then, we add the following scripts to create ImageResize function.

      ImageResize:
  Type: AWS::Serverless::Function
  Properties:
    CodeUri: fcj-book-shop/resize_image/function.zip
    PackageType: Zip
    Handler: index.handler
    Runtime: nodejs20.x
    FunctionName: resize_image
    Architectures:
      - x86_64
    Policies:
      - Statement:
          - Sid: ResizeUploadImage
            Effect: Allow
            Action:
              - s3:GetObject
              - s3:PutObject
              - s3:DeleteObject
            Resource:
              - !Sub "arn:aws:s3:::${bookImageShopBucketName}/*"
              - !Sub "arn:aws:s3:::${bookImageResizeShopBucketName}/*"
    Events:
      ResizeImage:
        Type: S3
        Properties:
          Bucket: !Ref BookImageShop
          Events: s3:ObjectCreated:*
    Environment:
      Variables:
        WIDTH: !Ref width
        HEIGHT: !Ref height
        DES_BUCKET: !Ref BookImageResizeShop

      LambdaResizeFunction

    • Next, add the following script at the end of the file to grant permission to the book-image-shop-by-myself bucket to use this function.

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

      LambdaResizeFunction

      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.

  3. The directory structure is as follows.

    fcj-book-shop
├── fcj-book-shop
│   ├── books_list
│   │   └── books_list.py
│   ├── book_create
│       └── requirements.txt
│   │   └── 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.
  4. function.zip (25985 ko)

  5. Run the following command to deploy SAM.

    sam build
sam validate
sam deploy

    LambdaResizeFunction

  6. Open AWS Lambda console.

    • Click resize_image function created. LambdaResizeFunction
    • At resize_image page.
      • Click Configuration tab.
      • Select Triggers on the left menu.
      • Click Details.
      • Check s3:ObjectCreated detail that we created before. LambdaResizeFunction
      • Click Configuration tab.
      • Select Permissions on the left menu.
      • Click on the role that the function is executing. LambdaResizeFunction
    • At fcj-book-shop-ImageResizeRole-… page.
      • Check the permissions granted to the function. LambdaResizeFunction