Ingest Lambda + S3 Trigger

Create Ingest Lambda

1. Go to Lambda → Create function

2. Select Author from scratch

3. Fill:

   • Function name: beetroot-ingest
   • Runtime: Python 3.14

4. Under Permissions:

   • Click Change default execution role
   • Select Use an existing role
   • Choose your role: beetroot-ingest-role (the role you created)

5. Click Create function

6. The Lambda function would have the following code inside it:

import json

def lambda_handler(event, context):
    print("S3 EVENT:")
    print(json.dumps(event))
    return {"ok": True}

7. To check if the Lambda function is working:

   • In the Lambda page, open the Test tab (above the code editor).
   • You can keep the default test event or edit it
   • Click on Test button
   • After it runs, open Details to see the response and logs. Expected response:

   {
     "statusCode": 200,
     "body": "\"Hello from Lambda!\""
   }

Add S3 trigger

1. Open Lambda → beetroot-ingest
2. Click Add trigger
3. Select S3
4. Bucket: beetroot-raw
5. Event type: All object create events (PUT is also fine)
6. Prefix: photos-raw/
7. Acknowledge the permission prompt → click Add

Checkpoint

This is what you should see after adding the S3 trigger:

End-to-End Test

Upload one new photo (so logs are easy to read):

aws s3 cp ./beetroot-test-photos/group1.jpg s3://beetroot-raw/photos-raw/ --region us-east-1

Verify via CloudWatch Logs

1. Open Lambda → beetroot-ingest
2. Go to Monitor → View CloudWatch logs
3. Open the latest log stream

In the logs, confirm you see S3 EVENT: {'Records': ...}