Serverless - Deploying applications with SAM > Deploy Lambda function > Deploy Lambda function > Resizing image Lmabda function

Resizing image Lmabda function

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

Open template.yaml file in fcj-book-store folder
Add the following script at the end of the file to create resizing image function

ImageResizer:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: fcj-book-store/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-store/*
                - arn:aws:s3:::book-image-resize-store/*
      Events:
        ResizeImage:
          Type: S3
          Properties:
            Bucket: !Ref BookImageStore
            Events: s3:ObjectCreated:*
      Environment:
        Variables:
          WIDTH: 200
          HEIGHT: 280
          DES_BUCKET: book-image-resize-store

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-store 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 BookImageStore.Arn

LambdaResizeFunction

The directory structure is as follows:

fcj-book-store
├── fcj-book-store
│   ├── 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-store/fcj-book-store/ folder
Download the below file and copy to this folder

Source code

function.zip (8382 ko)

Run the following command to deploy SAM

sam build
sam deploy

LambdaResizeFunction

Back to Lambda console

Click resize_image function created

LambdaResizeFunction

Click Configuration tab

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

LambdaResizeFunction

Select Permissions on the left menu

Click on the role that the function is executing

LambdaResizeFunction

Expand the policy, see the permissions granted to the function

LambdaResizeFunction