MLA-C01 Deployment and Orchestration of ML Workflows Practice Question

A company wants to trigger a model retraining pipeline whenever new training data arrives in an S3 bucket. They also need to send a notification to a Slack channel when the retraining completes. Which TWO AWS services should they use to implement this event-driven workflow? (Select TWO.)

⚠ Common exam trap

A common pitfall is confusing event-trigger services (Lambda, EventBridge) with storage/audit services (SQS, CloudTrail, Model Registry). Candidates often select SQS for decoupling or CloudTrail for monitoring, but these do not directly trigger the retraining or send notifications in an event-driven manner.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

AWS Lambda

AWS Lambda is correct because it can be triggered directly by S3 events (e.g., s3:ObjectCreated) to invoke the model retraining pipeline. Amazon EventBridge is correct because it can capture completion events from the retraining pipeline (e.g., SageMaker training job state changes) and route them to a target like a Slack webhook via Lambda or SNS, enabling the notification workflow.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
AWS Lambda
Why this is correct
AWS Lambda provides the compute layer that reacts to the S3 event notification, invoking code to start the retraining pipeline without polling. It satisfies the event-driven trigger requirement, and the same function can publish to Slack via a webhook once retraining completes, meeting the notification constraint.
✗
AWS CloudTrail
Why it's wrong here
CloudTrail records API activity for auditing and governance; it does not emit S3 object-created events to a pipeline target or deliver Slack messages. It is tempting because it captures bucket-level API calls, and would be correct for auditing who deleted or modified training data.
✓
Amazon EventBridge
Why this is correct
Amazon EventBridge routes S3 event notifications to the retraining pipeline, satisfying the requirement to trigger on new training data arrival. Its rule-based event bus decouples the bucket from downstream targets, so completion events can also fan out to Slack via a Lambda target or API destination.
✗
SageMaker Model Registry
Why it's wrong here
The Model Registry catalogues and versions trained models; it neither reacts to S3 object creation nor posts to Slack, so it cannot initiate the pipeline. It is tempting because it tracks model lineage and approval status, and would be correct for promoting a model from staging to production.

Quick reference

AWS S3 Storage Class Comparison

Storage Class	Min Duration	Retrieval	Use Case
S3 Standard	None	Immediate	Frequently accessed data
S3 Standard-IA	30 days	Immediate	Infrequent access, rapid retrieval
S3 One Zone-IA	30 days	Immediate	Non-critical infrequent data
S3 Intelligent-Tiering	None	Immediate–hours	Unknown or changing access patterns
S3 Glacier Instant	90 days	Milliseconds	Archive with instant retrieval
S3 Glacier Flexible	90 days	Minutes–hours	Archive, flexible retrieval
S3 Glacier Deep Archive	180 days	Hours	Long-term compliance archive

Go deeper

MLA-C01 Deployment and Orchestration of ML Workflows Practice Question

Why each option matters

Option-by-option breakdown

AWS S3 Storage Class Comparison

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