Jeff’s Note #
Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.
For DVA-C02 candidates, the confusion often lies in choosing between containerized or serverless scheduled tasks. In production, this hinges on knowing exactly which AWS service minimizes operational overhead while meeting scheduled execution needs. Let’s drill down.
The Certification Drill (Simulated Question) #
Scenario #
DataStrata Inc., a startup, wants to build a small application that triggers an external API call once daily at a precise time. They currently have no pre-existing AWS infrastructure and want to leverage AWS best practices for minimal operational overhead.
The Requirement: #
Design a solution that performs the scheduled API call once a day at the specified time with the MOST operational efficiency.
The Options #
- A) Use a Kubernetes cron job running within Amazon Elastic Kubernetes Service (EKS).
- B) Use a Linux cron job scheduled on an Amazon EC2 instance running Amazon Linux.
- C) Use an AWS Lambda function invoked daily by an Amazon EventBridge scheduled event.
- D) Use an AWS Batch job submitted to an AWS Batch job queue once per day.
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Correct Answer #
C) Use an AWS Lambda function invoked daily by an Amazon EventBridge scheduled event.
Quick Insight: The Developer Efficiency Imperative #
- Serverless architectures like Lambda invoked by EventBridge scheduled rules provide zero infrastructure management and automatically scale without idle charges.
- Alternatives like EKS cron jobs or EC2 cron require managing servers or clusters, costing more time and operational effort.
- AWS Batch is overkill for simple daily scheduled API calls and adds unnecessary complexity.
Content Locked: The Expert Analysis #
You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?
The Expert’s Analysis #
Correct Answer #
Option C
The Winning Logic #
This scenario is a classic candidate for a serverless scheduled event with minimal operational overhead:
- AWS Lambda functions are ideal for lightweight tasks such as invoking APIs without provisioning or managing servers.
- Amazon EventBridge (formerly CloudWatch Events) allows creation of cron-like scheduled rules to trigger Lambda functions reliably at the specified time.
- This combination eliminates downtime risks, patching, or scaling burdens.
- Lambda pricing is based on execution time and resources used, often cheaper for low-frequency, short jobs.
- The developer can focus on code, not infrastructure.
The Trap (Distractor Analysis) #
- Option A (EKS cron job): Requires provisioning, managing and patching Kubernetes clusters, a complex over-engineering for a simple scheduled call. Also incurs higher cost and operational overhead.
- Option B (EC2 cron): Involves managing an EC2 instance 24/7 just to run one daily task, leading to unnecessary cost and maintenance effort.
- Option D (AWS Batch): Designed for large-scale batch processing jobs, it is disproportionately complex and operationally heavy for this use case.
The Technical Blueprint #
# CLI snippet to create an EventBridge rule triggering Lambda daily at 9:00 AM UTC
aws events put-rule --schedule-expression "cron(0 9 * * ? *)" --name DailyApiTrigger
# Lambda function grant permission to EventBridge
aws lambda add-permission --function-name DailyApiCall --statement-id EventBridgeInvoke --action 'lambda:InvokeFunction' --principal events.amazonaws.com --source-arn arn:aws:events:region:account-id:rule/DailyApiTrigger
# Add the Lambda function as the target of the EventBridge rule
aws events put-targets --rule DailyApiTrigger --targets "Id"="1","Arn"="arn:aws:lambda:region:account-id:function:DailyApiCall"
The Comparative Analysis #
| Option | API Complexity | Performance | Use Case |
|---|---|---|---|
| A) EKS | High (K8s APIs, manifests) | High availability | Heavy cronjobs requiring container dependencies |
| B) EC2 | Moderate (cron, SSH, OS) | Depends on instance | Legacy workloads; requires managing OS |
| C) Lambda + EventBridge | Low (event-driven scheduling) | Fast cold start, scales automatically | Lightweight tasks, minimal ops |
| D) AWS Batch | High (job definitions, queues) | Designed for batch jobs | Large scale batch processing |
Real-World Application (Practitioner Insight) #
Exam Rule #
“For the exam, always pick Lambda + EventBridge when you see a simple daily scheduled task with no existing infrastructure.”
Real World #
“In production, even if customers run containerized stacks, serverless often wins for isolated scheduled tasks because it dramatically reduces cost and ops burden.”
(CTA) Stop Guessing, Start Mastering #
Disclaimer
This is a study note based on simulated scenarios for the AWS DVA-C02 exam.