CI/CD pipeline for Express apps - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this GitHub Actions step?

Given this GitHub Actions step in a CI pipeline for an Express app, what will be the output if the tests fail?

Express

steps:
  - name: Run tests
    run: npm test

A The pipeline stops and marks the job as failed.

B The pipeline skips the test step and marks it as successful.

C The pipeline retries the test step automatically.

D The pipeline continues to the next step regardless of test results.

💡 Hint

By default, a failing command in GitHub Actions stops the job.

In GitHub Actions, if a command like 'npm test' fails (returns non-zero), the job stops and is marked failed unless you explicitly allow failure.

❓ Configuration

intermediate

Which Dockerfile snippet correctly sets up an Express app for production?

Choose the Dockerfile snippet that correctly installs dependencies and starts the Express app in production mode.

A

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

B

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

C

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

D

FROM node:18
WORKDIR /app
COPY package*.json ./
RUN npm install --only=production
COPY . .
CMD ["node", "server.js"]

💡 Hint

Production installs only needed packages and uses the correct start file.

Option D installs only production dependencies and starts the app with 'node server.js', which is typical for Express apps in production.

🔀 Workflow

advanced

What is the correct order of steps in a CI/CD pipeline for an Express app?

Arrange these steps in the correct order for a typical CI/CD pipeline deploying an Express app.

A 4,2,1,3

B 4,1,2,3

C 1,4,2,3

D 2,4,1,3

💡 Hint

Code must be pushed before tests run, then build and deploy.

First, code is pushed (4), then tests run (1), then Docker image is built (2), and finally deployed (3).

❓ Troubleshoot

advanced

Why does this GitHub Actions step fail with 'npm: command not found'?

In a GitHub Actions workflow for an Express app, this step fails: - name: Install dependencies run: npm install What is the most likely cause?

A The npm install command is misspelled.

B The package.json file is missing in the repository.

C The runner does not have Node.js installed or the PATH is incorrect.

D The workflow YAML syntax is invalid.

💡 Hint

Check if Node.js is available on the runner environment.

If 'npm' is not found, it usually means Node.js is not installed or PATH is not set correctly on the runner.

✅ Best Practice

expert

Which practice improves CI/CD pipeline speed for Express apps?

Select the best practice to speed up the CI/CD pipeline when building Docker images for Express apps.

A Use multi-stage Docker builds to separate dependencies installation from app code copying.

B Always run npm install without caching to ensure fresh dependencies.

C Build the Docker image on every commit without using any cache.

D Push the Docker image to the registry before running tests.

💡 Hint

Separating layers helps Docker cache dependencies and avoid reinstalling them every build.

Multi-stage builds and caching dependencies speed up builds by reusing layers when code changes but dependencies don't.