Building images in CI pipeline in Docker - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of Docker build with cache disabled

What will be the output status of the following command when run in a CI pipeline?

docker build --no-cache -t myapp:latest .

Docker

docker build --no-cache -t myapp:latest .

A Build command is invalid and returns a syntax error.

B Build fails due to missing cache layers.

C Build uses cached layers and completes faster.

D Build completes successfully creating a new image without using any cached layers.

💡 Hint

The --no-cache option forces Docker to ignore cached layers.

Using --no-cache tells Docker to build every step fresh, so no cached layers are used. This ensures the image is built from scratch.

✅ Best Practice

intermediate

Choosing the best base image in CI builds

In a CI pipeline, which base image choice is best to minimize build time and image size for a Node.js application?

A Use the full 'node:latest' image with all tools included.

B Use 'node:alpine' image which is smaller and lightweight.

C Use 'ubuntu:latest' and install Node.js manually during build.

D Use 'scratch' base image with no pre-installed software.

💡 Hint

Smaller base images reduce download and build time in CI.

The 'node:alpine' image is a lightweight version optimized for smaller size and faster builds, ideal for CI pipelines.

❓ Troubleshoot

advanced

Diagnosing Docker build failure in CI

A CI pipeline fails at the Docker build step with the error:

failed to solve with frontend dockerfile.v0: failed to read dockerfile: open /workspace/Dockerfile: no such file or directory

What is the most likely cause?

A The Dockerfile syntax has errors causing parsing failure.

B Docker daemon is not running on the CI server.

C The Dockerfile is missing or not in the build context directory.

D The image tag name is invalid.

💡 Hint

Check the location and presence of the Dockerfile in the repository.

The error indicates Docker cannot find the Dockerfile in the specified build context, usually because it is missing or misplaced.

🔀 Workflow

advanced

Correct order of steps in a CI Docker build pipeline

Arrange the following steps in the correct order for a typical CI pipeline that builds and pushes a Docker image:

A 4, 2, 3, 1

B 4, 3, 2, 1

C 2, 4, 3, 1

D 3, 4, 2, 1

💡 Hint

You need source code before testing and building, and push last.

First checkout code, then run tests to verify correctness, then build the image, and finally push it to the registry.

🧠 Conceptual

expert

Effect of multi-stage builds on CI pipeline efficiency

How do multi-stage Docker builds improve CI pipeline efficiency?

A They reduce the final image size by separating build and runtime stages, speeding up deployment.

B They allow parallel builds of multiple images in one Dockerfile.

C They cache all intermediate layers to speed up rebuilds regardless of changes.

D They automatically push images to multiple registries simultaneously.

💡 Hint

Think about how separating build tools from runtime affects image size.

Multi-stage builds let you use heavy tools in early stages and copy only needed artifacts to the final image, making it smaller and faster to deploy.