CI/CD pipeline for Flask - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of a GitHub Actions workflow step for Flask testing

Given this GitHub Actions step that runs Flask tests, what is the output if all tests pass?

      - name: Run tests
        run: |
          python -m venv venv
          source venv/bin/activate
          pip install -r requirements.txt
          pytest tests/

A All tests passed successfully with no errors.

B SyntaxError: invalid syntax in requirements.txt

C ModuleNotFoundError: No module named 'pytest'

D Tests failed with assertion errors.

💡 Hint

Think about what happens when pytest runs and all tests pass.

If all tests pass, pytest outputs a success message and exits with code 0, so the step completes successfully.

❓ Configuration

intermediate

Correct Dockerfile for a Flask app in CI/CD

Which Dockerfile configuration correctly builds a Flask app image for deployment in a CI/CD pipeline?

A

FROM python:3.12-slim
WORKDIR /app
COPY . /app
RUN pip install -r requirements.txt
CMD ["python", "app.py"]

B

FROM node:18
WORKDIR /app
COPY . /app
RUN npm install
CMD ["node", "app.js"]

C

FROM python:3.12
COPY requirements.txt /
RUN pip install -r /requirements.txt
COPY . /app
WORKDIR /app
CMD ["flask", "run"]

D

FROM python:3.12
WORKDIR /app
COPY . /app
RUN pip install -r requirements.txt
CMD ["flask", "run", "--host=0.0.0.0"]

💡 Hint

Flask apps need to listen on all interfaces in containers.

Option D sets the working directory, copies files, installs dependencies, and runs Flask on 0.0.0.0 so it is accessible outside the container.

🔀 Workflow

advanced

Order of steps in a CI/CD pipeline for Flask

Arrange these steps in the correct order for a typical CI/CD pipeline for a Flask app:

A 1,2,3,4

B 2,1,3,4

C 1,3,2,4

D 3,2,1,4

💡 Hint

Tests must pass before building and pushing images.

First run tests to verify code, then build the Docker image, push it to a registry, and finally deploy it.

❓ Troubleshoot

advanced

Error when deploying Flask app: "Address already in use"

You deployed your Flask app in a container but get the error: "OSError: [Errno 98] Address already in use". What is the most likely cause?

A The Dockerfile is missing the requirements.txt file.

B The Flask app is trying to bind to a port already used by another process.

C The Flask app code has a syntax error.

D The container image was not pushed to the registry.

💡 Hint

This error usually means the port is busy.

The error means the port Flask tries to use is already occupied, often by another app or container.

✅ Best Practice

expert

Best practice for secret management in CI/CD for Flask

What is the best practice to handle sensitive environment variables like API keys in a CI/CD pipeline for a Flask app?

A Store secrets directly in the Flask app source code.

B Commit secrets in a separate config file in the repository.

C Use environment variables set securely in the CI/CD platform and inject them at runtime.

D Print secrets in the CI/CD logs for debugging.

💡 Hint

Think about security and avoiding exposure of secrets.

Storing secrets in environment variables managed by the CI/CD system keeps them out of source code and logs.