Create four access points that allow access to the central S3 bucket. Assign an access point to each web application bucket.

Create a bucket policy that allows access to the central S3 bucket. Attach the bucket policy to the central S3 bucket.

Create a cross-origin resource sharing (CORS) configuration that allows access to the central S3 bucket. Add the CORS configuration to the central S3 bucket.

Create a Content-MD5 header that provides a message integrity check for the central S3 bucket. insert the Content-MD5 header for each web application request.

Sequential

instanceID_log-HH-DD-MM-YYYY

instanceID_log-YYYY-MM-DD-HH

HH-DD-MM-YYYY-log_instanceID

YYYY-MM-DD-HH-log_instanceID

Upload an object to Amazon S3 by using the aws s3api put-object CLI command. Wait for the local Lambda invocation from the S3 event.

Create a sample JSON text file for a put object S3 event. Invoke the Lambda function locally. Use the aws lambda invoke CLI command with the JSON file and Lambda function name as arguments.

Use the sam local start-lambda CLI command lo start Lambda. Use the sam local generate-event s3 put CLI command to create the Lambda test JSON file. Use the sam local invoke CLI command with the JSON file as the argument to invoke the Lambda function.

Create a JSON string for the put object S3 event. In the AWS Management Console, use the JSON string to create a test event for the local Lambda function. Perform the test.