- A
gcloud run deploy --image ... --canary-percent=5
Why wrong: Incorrect. The `--canary-percent` flag does not exist in `gcloud run deploy`. The correct flag for setting traffic percentage is `--traffic`.
- B
gcloud run deploy --image ... --traffic=5
Correct. The `--traffic` flag sets the percentage of traffic for the newly deployed revision. This command starts a canary deployment with 5% traffic to the new revision.
- C
gcloud run deploy --image ... --to-revisions=REVISION_1=95,REVISION_2=5
Why wrong: Incorrect. The `--to-revisions` flag is used to specify traffic splits by revision name, but at deploy time the revision name is not known. It is typically used after the revision exists to update traffic distribution.
- D
gcloud run deploy --image ... --min-instances=1 --max-instances=10
Why wrong: Incorrect. The `--min-instances` and `--max-instances` flags control the number of container instances, not traffic routing. They do not set the initial traffic percentage.
PCDE Canary deployment Practice Question
This PCDE practice question tests your understanding of building and implementing ci/cd pipelines for a service. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: canary deployment. 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 company uses Cloud Run and wants to deploy a new revision that initially receives 5% of traffic, and only if it's healthy, gradually increase to 100%. Which gcloud command should they use?
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
gcloud run deploy --image ... --traffic=5
Option B is correct because the `gcloud run deploy` command with the `--traffic` flag allows you to deploy a new revision and immediately set the percentage of traffic it should receive. By specifying `--traffic=5`, the new revision gets 5% of traffic, while the previous revision keeps the remaining 95%. This initiates a canary deployment. The gradual increase to 100% must be managed separately using `gcloud run services update-traffic` commands or an automated pipeline, but the initial command is correct for starting the canary.
Key principle: Canary deployment
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
gcloud run deploy --image ... --canary-percent=5
Why it's wrong here
Incorrect. The `--canary-percent` flag does not exist in `gcloud run deploy`. The correct flag for setting traffic percentage is `--traffic`.
- ✓
gcloud run deploy --image ... --traffic=5
Why this is correct
Correct. The `--traffic` flag sets the percentage of traffic for the newly deployed revision. This command starts a canary deployment with 5% traffic to the new revision.
Related concept
Canary deployment
- ✗
gcloud run deploy --image ... --to-revisions=REVISION_1=95,REVISION_2=5
Why it's wrong here
Incorrect. The `--to-revisions` flag is used to specify traffic splits by revision name, but at deploy time the revision name is not known. It is typically used after the revision exists to update traffic distribution.
- ✗
gcloud run deploy --image ... --min-instances=1 --max-instances=10
Why it's wrong here
Incorrect. The `--min-instances` and `--max-instances` flags control the number of container instances, not traffic routing. They do not set the initial traffic percentage.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap is that candidates may think the `--to-revisions` flag is the correct way to set initial traffic for a new revision, but it requires knowing the revision name beforehand. The `--traffic` flag is specifically designed for deploying a new revision with a controlled traffic split.
Detailed technical explanation
How to think about this question
Cloud Run uses a traffic management system based on revision-level routing, where each revision can be assigned a percentage of traffic via the `--to-revisions` flag. The gradual rollout is achieved by Cloud Run's internal health-checking mechanism: if the new revision fails health checks (e.g., HTTP 500 errors or timeout), the rollout automatically stops and rolls back to the previous revision. This is distinct from a simple static traffic split, as the platform monitors the revision's readiness and liveness probes to determine if the traffic increase should proceed.
KKey Concepts to Remember
- Canary deployment
- gcloud run deploy --traffic
- Traffic splitting
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
Canary deployment
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Canary deployment Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Review canary deployment, then practise related PCDE questions on the same topic to reinforce the concept.
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FAQ
Questions learners often ask
What does this PCDE question test?
Building and Implementing CI/CD Pipelines for a Service — This question tests Building and Implementing CI/CD Pipelines for a Service — Canary deployment.
What is the correct answer to this question?
The correct answer is: gcloud run deploy --image ... --traffic=5 — Option B is correct because the `gcloud run deploy` command with the `--traffic` flag allows you to deploy a new revision and immediately set the percentage of traffic it should receive. By specifying `--traffic=5`, the new revision gets 5% of traffic, while the previous revision keeps the remaining 95%. This initiates a canary deployment. The gradual increase to 100% must be managed separately using `gcloud run services update-traffic` commands or an automated pipeline, but the initial command is correct for starting the canary.
What should I do if I get this PCDE question wrong?
Review canary deployment, then practise related PCDE questions on the same topic to reinforce the concept.
What is the key concept behind this question?
Canary deployment
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Last reviewed: Jul 4, 2026
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