The answer is to use Cloud Build’s built-in caching with a persistent volume to store node_modules between builds. This approach works because Cloud Build allows you to mount a persistent volume, such as `/cache`, in your `cloudbuild.yaml`, and by running `npm ci --prefer-offline`, the pipeline reuses previously downloaded dependencies instead of fetching them from the registry each time. On the Google Professional Cloud Developer exam, this scenario tests your understanding of how to reduce build time for Cloud Run deployments by leveraging Cloud Build’s volume caching rather than external services like Cloud Storage or manual layer caching in Dockerfiles. A common trap is assuming that Docker layer caching alone is sufficient for Node.js dependencies, but persistent volumes are more reliable for large `node_modules` trees across separate build steps. Memory tip: think “persistent volume for persistent pain points”—caching `node_modules` on a volume keeps your builds fast and your pipeline lean.
PCD Building and testing applications Practice Question
This PCD practice question tests your understanding of building and testing applications. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 developer is designing a CI/CD pipeline for a Node.js application hosted on Cloud Run using Cloud Build. The pipeline should run unit tests, build the container, push to Artifact Registry, and deploy to Cloud Run. The developer wants to minimize build time by caching dependencies. What is the recommended approach?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Cloud Build's built-in caching with a persistent volume to store node_modules between builds.
Option D is correct because Cloud Build supports built-in caching via persistent volumes (e.g., `/cache` or `/workspace`) that can store `node_modules` across builds. By configuring a cache volume in the `cloudbuild.yaml` and using `npm ci --prefer-offline`, the pipeline avoids re-downloading dependencies on every run, significantly reducing build time for Node.js applications on Cloud Run.
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.
✗
Run npm install locally and commit the node_modules folder to the repository for faster builds.
Why it's wrong here
Committing node_modules is not best practice and increases repository size.
✗
Use Cloud Build's step-level caching by copying the node_modules from a previous build step.
Why it's wrong here
Step-level caching does not persist across separate builds.
✗
Create a custom base image that includes all dependencies and reference it in the Dockerfile.
Why it's wrong here
This approach works but is less flexible and requires maintaining the base image.
✓
Use Cloud Build's built-in caching with a persistent volume to store node_modules between builds.
Why this is correct
Cloud Build's volume caching allows dependency caching across builds.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that committing `node_modules` or using custom base images are efficient caching strategies, but the correct approach is to use Cloud Build's native persistent volume caching, which is purpose-built for this scenario.
Detailed technical explanation
How to think about this question
Cloud Build's persistent volume caching uses a `volumes` field in `cloudbuild.yaml` to mount a shared directory (e.g., `/cache`) across steps, allowing `npm cache` or `node_modules` to persist between builds. Under the hood, Cloud Build uses Google Cloud Storage buckets to store the cache, which is automatically managed and pruned. In real-world scenarios, combining this with `npm ci` (which uses `package-lock.json` for deterministic installs) ensures both speed and reproducibility, especially for large monorepos or projects with many dependencies.
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 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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Building and testing applications — This question tests Building and testing applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Cloud Build's built-in caching with a persistent volume to store node_modules between builds. — Option D is correct because Cloud Build supports built-in caching via persistent volumes (e.g., `/cache` or `/workspace`) that can store `node_modules` across builds. By configuring a cache volume in the `cloudbuild.yaml` and using `npm ci --prefer-offline`, the pipeline avoids re-downloading dependencies on every run, significantly reducing build time for Node.js applications on Cloud Run.
What should I do if I get this PCD question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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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