📌 Purpose

This Lambda function is triggered when an image is uploaded to a specific path in an S3 bucket (ss-au-bank-preprod/smartsell/pages_1/). It checks if the image is in Non-RGB color space and, if so, converts it to RGB, uploads it back to S3 (overwriting the original), and invalidates the CloudFront CDN cache for the updated file.

✅ Core Features

• ✅ Detect Non-RGB images using PIL (Pillow)
• ✅ Convert Non-RGB images to RGB
• ✅ Re-upload image to S3 at the same key a
• ✅ Invalidate CloudFront cache
• ✅ Record conversionTimeSec and isRGBProcessed as an S3 tag
• ✅ Send Slack alerts on failure with relevant metadata

⚙️ Environment Variables

Variable	Description
CDN_BASE_URL	Base URL of the CDN (used for Slack notifications)
CLOUDFRONT_DISTRIBUTION_ID	CloudFront distribution ID for cache invalidation
TARGET_BUCKET_NAME	S3 bucket name for triggering lambda

🔐 Secrets

Secret Name	Description
SLACK_CMYKTORGB_ALERT_API_TOKEN = {slack_api_token:’token_value’}
Slack Bot OAuth token to send alerts to Slack channel #Non-RGBtorgb-alerts

🚨 Failure Scenarios & Slack Alerts

Scenario	Slack Alert Triggered	Slack Message Preview
File not in smartsell/pages_1/	❌ No	No alert — file ignored silently
File is already tagged isRGBProcessed: true	❌ No	No alert — file considered already processed
File retry count >= 3 while image conversion	✅ Yes	Max retries reached for file: {filename}
S3 download failure	✅ Yes	Error while downloading file from S3: {filename}
Image is invalid or corrupted (Pillow error)	✅ Yes	Library related issues occurred while processing file: {filename}
Image is not Non-RGB (e.g., already RGB)	❌ No	No alert — image skipped as it's not in Non-RGB mode
Conversion succeeded	❌ No	No alert — success
Upload back to S3 fails	✅ Yes	Failed to upload RGB image to S3: {filename}
Tagging fails	✅ Yes	Failed to tag image on S3: {filename}
CloudFront invalidation fails	✅ Yes	CloudFront invalidation failed for: {cdn_url}
Any unexpected runtime exception	✅ Yes	{exception error message} (dynamically included)

Slack message example:

Non-RGB to RGB Conversion Failed
Original File: abc123.pdf
CDN URL: https://cdn.example.com/smartsell/pages_1/abc123.pdf
Retries: 3
Error: Max retries reached
System Error: Reason for the error

✅ AWS Setup

• ✅ Assumes your S3 bucket and CloudFront distribution are already set up.

  • A. Create a Lambda Function

    • Go to AWS Lambda → Create function → Author from scratch.
    • Assign a name, e.g., Non-RGB-to-rgb-converter.
    • Choose Python 3.9+ as the runtime.
    • Upload the zipped deployment package or deploy via SAM/Serverless Framework.
    • Add Pillow and Requests dependencies as layers

  • B. Create & Attach an IAM Role to Lambda

    • You will need to create an IAM Role and attach it to the Lambda function with these permissions:

  S3 Access:

  • Permission to:
    • Get objects
    • Put objects
    • Get and put object tags
  • Only for files under: your-bucket-name/smartsell/pages_1/

  CloudFront Access:

  • Permission to create cache invalidations

  Secrets Manager Access:

  • Permission to read one secret:
    • Name: SLACK_Non-RGBTORGB_ALERT_API_TOKEN

  C. Set Environment Variables

  In Lambda → Configuration → Environment variables, add:

  Key	Value
  TARGET_BUCKET_NAME	your S3 bucket name
  CDN_BASE_URL	your CloudFront URL (e.g., https://cdn.example.com)
  CLOUDFRONT_DISTRIBUTION_ID	Your CloudFront distribution ID

D. Store Slack Token in Secrets Manager

1. Go to Secrets Manager > Store a new secret.

2. Choose Other type of secret.

3. Set the key-value pair:

   {
     "slack_api_token": "xoxb-XXXXXXXXXX"
   }
   

   Name it exactly: SLACK_CMYKTORGB_ALERT_API_TOKEN

🔁 S3 Event Trigger Setup

1. Go to S3 > Your Bucket > Properties > Event notifications
2. Add a new event notification:
   • Event type: PUT (ObjectCreated)
   • Prefix filter: smartsell/pages_1/
   • Destination: Lambda → Select your function

🧪 Debugging & Observability

• View logs in CloudWatch Logs → Linked from the Lambda function page.
• Failures trigger a Slack message to #cmyktorgb-alerts with:
  • File name
  • CDN URL
  • Retry count
  • Error message