Deploying from CI/CD pipeline in Docker - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of Docker command in CI/CD

You run this command in your CI pipeline to build and tag a Docker image:

docker build -t myapp:latest .

What will be the output if the Dockerfile is missing in the current directory?

Docker

docker build -t myapp:latest .

A Successfully built and tagged myapp:latest

B Build completed but image not tagged

C Warning: No Dockerfile specified, using default

D Error response from daemon: Dockerfile not found

💡 Hint

Think about what Docker needs to build an image.

Docker requires a Dockerfile in the specified directory to build an image. If missing, it returns an error saying Dockerfile not found.

🔀 Workflow

intermediate

Correct order of CI/CD deployment steps

Arrange these steps in the correct order for deploying a Dockerized app from a CI/CD pipeline:

A 3,2,1,4

B 2,3,1,4

C 3,1,2,4

D 1,3,2,4

💡 Hint

Think about building before testing and pushing.

First build the image, then test it, push it to registry, and finally deploy it.

❓ Troubleshoot

advanced

Troubleshooting failed Docker push in CI

In your CI pipeline, the Docker push command fails with:

denied: requested access to the resource is denied

What is the most likely cause?

Docker

docker push myregistry.com/myapp:latest

A You are not logged in to the Docker registry

B The Dockerfile has syntax errors

C The image was not built before push

D The Docker daemon is not running

💡 Hint

Think about permissions and authentication.

The error means the registry denied access, usually because the user is not logged in or lacks permissions.

🧠 Conceptual

advanced

Why use multi-stage builds in CI/CD pipelines?

What is the main benefit of using multi-stage Docker builds in a CI/CD pipeline?

A It automatically deploys the image after build

B It allows running multiple containers simultaneously

C It reduces the final image size by separating build and runtime stages

D It speeds up the Docker daemon startup time

💡 Hint

Think about image size and efficiency.

Multi-stage builds let you copy only necessary artifacts to the final image, making it smaller and more secure.

✅ Best Practice

expert

Secure handling of secrets in CI/CD Docker deployments

Which method is the safest way to handle sensitive environment variables (like passwords) during Docker image deployment in a CI/CD pipeline?

A Pass secrets as plain text arguments during docker build

B Store secrets in the CI/CD platform's secret manager and inject at runtime

C Include secrets in the source code repository in a .env file

D Hardcode secrets in the Dockerfile using ENV instructions

💡 Hint

Think about avoiding exposure of secrets in images or code.

Using the CI/CD platform's secret manager keeps secrets out of code and images, injecting them securely at runtime.