AWS DVA-C02 Drill: EventBridge CodeCommit Events - Lambda Triggering for PR Validation

Jeff’s Note

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Unlike generic exam dumps, ADH analyzes this scenario through the lens of a Real-World Lead Developer.

For AWS DVA-C02 candidates, the confusion often lies in knowing which CodeCommit event names appear in EventBridge for pull request lifecycle events. In production, this means you need exact event names to properly trigger Lambda functions and automate CI/CD failing or passing gates. Let’s drill down.

The Certification Drill (Simulated Question)

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Scenario

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NovaApps is building an automated pipeline to enforce code quality before merging pull requests into their main branch. Developers store application code in AWS CodeCommit. NovaApps uses AWS CodeBuild to run unit tests. To automate triggering tests, a Lambda function is created that starts CodeBuild when pull requests are created or updated.

The team wants to use Amazon EventBridge to detect the correct CodeCommit events representing pull request creation and source branch updates, so the Lambda function can be invoked timely and reliably.

The Requirement:

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Select the correct Amazon EventBridge detail.event value(s) emitted by AWS CodeCommit to invoke the Lambda when a pull request is either created or its source branch is updated.

The Options

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• A) { "source":"aws.codecommit", "detail": { "event":"pullRequestApprovalRuleCreated" } }
• B) -
• C) { "source":"aws.codecommit", "detail": { "event":"pullRequestSourceBranchUpdated", "pullRequestCreated" } }
• D) { "detail":{ "source":"aws.codecommit", "event":"pullRequestUpdated","pullRequestSourceBranchCreated" } }

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Correct Answer

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C

Quick Insight: The Developer Imperative

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• The specific CodeCommit EventBridge detail.event values for pull request lifecycle are exact string identifiers.
• “pullRequestSourceBranchUpdated” and “pullRequestCreated” are the events that correspond to source branch updates and PR creation.
• Properly filtering on these events enables Lambda triggers to automate CodeBuild runs for PR validation.

Content Locked: The Expert Analysis

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You’ve identified the answer. But do you know the implementation details that separate a Junior from a Senior?

The Expert’s Analysis

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Correct Answer

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Option C

The Winning Logic

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AWS CodeCommit produces very specific event values in Amazon EventBridge for pull request lifecycle actions. Among these, pullRequestCreated denotes the creation of a pull request, and pullRequestSourceBranchUpdated denotes when the source branch of the PR receives new commits or updates.

For automating CI/CD workflows that kick off unit tests on any new PR or code update within that PR, your Lambda needs to listen exactly to these events.

• Option C correctly lists these event types together under the "detail": { "event": [...] } structure, making it the suitable trigger.

• The Lambda can parse EventBridge events with these values and programmatically start the CodeBuild job to run unit tests.

The Trap (Distractor Analysis)

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• Why not Option A?
  "pullRequestApprovalRuleCreated" relates to approval rules on a PR but does not trigger on creation or source branch updates. It’s irrelevant for automatic test runs on code changes.

• Why not Option B?
  Missing option, no context.

• Why not Option D?
  EventBridge events always have "source" at the top level, not inside "detail". Also, "pullRequestUpdated" and "pullRequestSourceBranchCreated" are not official event names from CodeCommit. These are invalid or malformed event values.

The Technical Blueprint

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# Example AWS CLI EventBridge rule to capture PR creation and source branch updates:

aws events put-rule \
  --name "TriggerLambdaOnPR" \
  --event-pattern '{
    "source": ["aws.codecommit"],
    "detail-type": ["CodeCommit Pull Request State Change"],
    "detail": {
      "event": ["pullRequestCreated", "pullRequestSourceBranchUpdated"]
    }
  }'

The Comparative Analysis

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Real-World Application (Practitioner Insight)

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Exam Rule

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For the exam, always pick the pullRequestCreated and pullRequestSourceBranchUpdated events when working with CodeCommit PR lifecycle triggers in EventBridge.

Real World

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In practice, teams extend this with CodePipeline or use AWS CodeBuild’s native integration with CodeCommit triggers. But understanding the underlying EventBridge events unlocks advanced custom workflows and Lambda automation.

(CTA) Stop Guessing, Start Mastering

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Disclaimer

This is a study note based on simulated scenarios for the AWS DVA-C02 exam.