The answer is the missing permission is s3:GetObject. This is correct because when CodeBuild attempts to download artifacts from an S3 bucket, it is performing a read operation on the stored objects, and the s3:GetObject action is the specific IAM permission that grants read access to individual S3 objects. Without it, the service role can start builds and view logs, but the actual retrieval of artifact files is blocked, resulting in an access denied error. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this question tests your understanding of the precise permissions required for each phase of a build pipeline—a common trap is assuming that broader S3 bucket-level permissions like s3:ListBucket are sufficient, but object-level read access is the key. A helpful memory tip is to think of "Get" as "Get the file": if CodeBuild needs to pull an artifact, it must have s3:GetObject on the bucket or the specific object path.
DOP-C02 SDLC Automation Practice Question
This DOP-C02 practice question tests your understanding of sdlc automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A DevOps engineer is reviewing the IAM policy attached to a CodeBuild service role. The policy allows starting builds and viewing logs. However, when CodeBuild tries to download artifacts from an S3 bucket in the same account, it fails with an access denied error. What is the missing permission?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
s3:GetObject
The error occurs because CodeBuild needs to download artifacts from S3, which requires the s3:GetObject permission on the bucket or object. Without this permission, the service role cannot read the artifact files, even though it can start builds and view logs. The s3:GetObject action is the specific permission that grants read access to S3 objects.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
s3:GetObject
Why this is correct
To download artifacts from S3, GetObject permission is required.
Related concept
Read the scenario before looking for a memorised answer.
✗
kms:Decrypt
Why it's wrong here
KMS is not mentioned; the bucket likely does not use SSE-KMS.
✗
s3:PutObject
Why it's wrong here
PutObject is for uploading artifacts; the build downloads artifacts.
✗
logs:DescribeLogGroups
Why it's wrong here
Log permissions are sufficient; the error is about S3 access.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse s3:GetObject with s3:PutObject or assume KMS decryption is always required, but the direct cause is the lack of read access to the S3 object.
Detailed technical explanation
How to think about this question
Under the hood, CodeBuild uses the service role's IAM policy to make S3 GetObject API calls when fetching artifacts. If the bucket uses SSE-KMS, the role also needs kms:Decrypt and kms:GenerateDataKey permissions, but the core missing permission here is s3:GetObject. In real-world scenarios, this often occurs when the S3 bucket policy also requires explicit principal permissions or when the artifact is in a different account requiring cross-account trust.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: s3:GetObject — The error occurs because CodeBuild needs to download artifacts from S3, which requires the s3:GetObject permission on the bucket or object. Without this permission, the service role cannot read the artifact files, even though it can start builds and view logs. The s3:GetObject action is the specific permission that grants read access to S3 objects.
What should I do if I get this DOP-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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