DOP-C02 SDLC Automation Practice Question
A company uses AWS CodePipeline with an Amazon S3 source action. The pipeline deploys to an Amazon ECS Fargate service. The engineer notices that the pipeline does not automatically start when a new object is uploaded to the S3 bucket. The S3 bucket versioning is enabled. What is the most likely cause?
⚠ Common exam trap
Many candidates assume S3 versioning alone enables automatic pipeline triggers, but versioning only ensures object version tracking, not event-driven execution.
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
✓
The S3 bucket does not have event notifications configured for the pipeline
AWS CodePipeline with an S3 source action does not automatically detect new object uploads unless the S3 bucket is configured with event notifications that trigger the pipeline. Without these notifications, the pipeline must be started manually or via a webhook. Since versioning is enabled, the issue is not related to versioning but to the missing event notification configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The pipeline has manual approval required before the source stage
Why it's wrong here
A manual approval action in CodePipeline is a stage-level gate that pauses execution before a deployment or other downstream action can proceed; it cannot be placed 'before the source stage' because the source stage is always the first stage in a pipeline definition. If the pipeline never triggers when an object is uploaded to S3, the root cause lies upstream of pipeline execution itself, not in a manual approval that would only delay an already-started run.
- ✓
The S3 bucket does not have event notifications configured for the pipeline
Why this is correct
CodePipeline does not automatically poll an Amazon S3 source bucket for new objects unless the bucket has event notifications enabled to emit s3:ObjectCreated:* events to the pipeline. Without an Amazon CloudWatch Events rule or an S3 event notification configured to invoke the pipeline on object writes, the pipeline will only run manually or when explicitly started from the console, CLI, or SDK. This is the standard prerequisite for automatic triggering from an S3 source, and its absence explains why the pipeline remains idle after an upload.
- ✗
S3 versioning is not enabled on the bucket
Why it's wrong here
S3 versioning is not required for CodePipeline to detect changes or to trigger a run; the pipeline tracks the object version ID and only cares that a new object version is present when the source action runs. While enabling versioning is a best practice for source artifact consistency and rollback ability, the absence of versioning does not prevent event notifications or manual executions from working. Therefore, this condition may be operationally suboptimal but is not the reason the pipeline fails to trigger automatically on upload.
- ✗
The ECS service is not configured for blue/green deployments
Why it's wrong here
Blue/green deployments are a deployment strategy for ECS (using CodeDeploy) that affects how traffic is shifted during a deployment, not how the pipeline is triggered from an S3 source. The pipeline trigger depends exclusively on the source stage's detection mechanism (S3 event notifications or polling) and is completely independent of the deployment configuration of the target ECS service. Even a pipeline with rolling ECS deployment will trigger correctly as long as the S3 event notification is set up, so this is not a plausible cause for the pipeline never starting.
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
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This DOP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DOP-C02 exam.