The correct approach is to create a Dockerfile that uses the base runtime image and runs apt-get install. This is necessary because the App Engine flexible environment runs your application inside a Docker container based on a Google-provided runtime image, which only includes default system packages. To install system-level dependencies like libssl-dev that are missing from that image, you must customize the container by writing a Dockerfile that starts FROM the base image and then executes apt-get commands to add the required packages. On the Google Professional Cloud Developer exam, this question tests your understanding of how the flexible environment differs from the standard environment—specifically, that flexible gives you full control over the runtime via Docker. A common trap is assuming you can use a requirements.txt or app.yaml setting to install OS packages; those only handle Python libraries, not system-level tools. Memory tip: think “FROM + apt-get” for any OS-level dependency in flexible.
PCD Deploying applications Practice Question
This PCD practice question tests your understanding of deploying 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 needs to deploy a Python application to App Engine flexible environment. The application requires a specific version of a system package (libssl-dev) that is not included in the default runtime image. How should the developer install this package?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a Dockerfile that uses the base runtime image and runs apt-get install.
Option C is correct because the App Engine flexible environment runs your application in a Docker container based on a Google-provided runtime image. To install system packages like libssl-dev that are not included in the default image, you must customize the container by creating a Dockerfile that starts FROM the base runtime image and then runs apt-get install. This is the standard method for adding OS-level dependencies in the flexible environment.
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.
✗
Use a custom runtime that already includes the package.
Why it's wrong here
Custom runtime is an option but requires more effort; using a Dockerfile is the standard way.
✗
Specify the package in the app.yaml file under the 'libraries' section.
Why it's wrong here
app.yaml libraries are for language-specific libraries, not system packages.
✓
Create a Dockerfile that uses the base runtime image and runs apt-get install.
Why this is correct
A Dockerfile allows customizing the runtime, including system packages.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add the package name to the requirements.txt file.
Why it's wrong here
requirements.txt is for Python packages, not system packages.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse the 'libraries' section in app.yaml (which is for Python packages) with system package installation, or mistakenly think requirements.txt can handle OS-level dependencies, leading them to pick options B or D instead of the correct Dockerfile approach.
Detailed technical explanation
How to think about this question
Under the hood, the App Engine flexible environment uses a Dockerfile to build the container image. When you provide a Dockerfile, Google Cloud Build pulls the base runtime image (e.g., gcr.io/google-appengine/python) and executes your custom instructions, such as RUN apt-get update && apt-get install -y libssl-dev. This is essential for applications that depend on native libraries, like those using cryptography or OpenSSL, where the Python package (e.g., pyopenssl) requires the system library at compile time.
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.
Deploying applications — This question tests Deploying applications — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a Dockerfile that uses the base runtime image and runs apt-get install. — Option C is correct because the App Engine flexible environment runs your application in a Docker container based on a Google-provided runtime image. To install system packages like libssl-dev that are not included in the default image, you must customize the container by creating a Dockerfile that starts FROM the base runtime image and then runs apt-get install. This is the standard method for adding OS-level dependencies in the flexible environment.
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.
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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