Deleting Lambda function

We will create a Lambda function that deletes all items with the specified partition key and sort key in the DynamoDB table. And delete the image file in the S3 bucket:

  1. Click Create function LambdaListFunction

  2. Enter function name, ví dụ: book_delete

    • Select Python 3.9 for Runtime pattern
    • Click Create function LambdaListFunction

  3. Copy the below code block into lambda_function.py

    import boto3
import json

s3 = boto3.client('s3')
client = boto3.resource('dynamodb')

def get_image_name(image_path):
    str_image = image_path.split("/")
    for image_path_item in str_image:
        image_name = image_path_item

    return image_name;

def lambda_handler(event, context):
    error = None
    status = 200
    delete_id = event['pathParameters']
    delete_id['rv_id'] = 0

    table = client.Table("Books")
    image_path = ""

    try:
        data = table.get_item(Key = delete_id)
        image_path = data['Item']['image']
        image_name = get_image_name(image_path)
    except Exception as e:
        error = e

    try:
        response = table.query(
            ProjectionExpression="rv_id", 
            KeyConditionExpression="id = :id", 
            ExpressionAttributeValues={":id": delete_id['id']})

        for item in response['Items']:
            delete_id['rv_id'] = item['rv_id']
            print(delete_id)
            table.delete_item(Key = delete_id)

        print(image_name)
        s3.delete_object(Bucket='book-image-resize-store', Key=image_name)

    except Exception as e:
        error = e

    if error is None:
        message = 'successfully deleted item!'
    else:
        message = 'delete item fail'
        status = 400

    return {
            'statusCode': status,
            'body': message,
            'headers': {
                'Content-Type': 'application/json',
                'Access-Control-Allow-Origin': '*'
            },
        }
    • Click Deploy LambdaListFunction

      If you create S3 bucket with name different from the lab, replace it in line 42 of code

  4. Next, give the Lambda function permission to delete object from the S3 bucket and access to DynamoDB table.

    • Click Configuration tab

    • Select Permissions pattern on the left menu

    • Click on the role the function is executing LambdaListFunction

    • Click on the existing policy that starts with AWSLambdaExecutionRole-

    • Click Edit policy LambdaListFunction

    • Click JSON tab and add the blow json block:

      ,
        {
            "Effect": "Allow",
            "Action": [
                "dynamodb:DeleteItem",
                "dynamodb:GetItem",
                "dynamodb:Query",
                "s3:DeleteObject"
            ],
            "Resource": [
                "arn:aws:dynamodb:AWS_REGION:ACCOUNT_ID:table/Books",
                "arn:aws:s3:::book-image-resize-store/*"
            ]
        }

    • Replace AWS_REGION with the region where you create the table in DynamoDB, such as: ap-southeast-2

    • Replace ACCOUNT_ID with your account id

    • Click Review policy LambdaListFunction

    • Review the settings and click Save changes LambdaListFunction