Installing with Docker in Jenkins - Practice Exercises

Challenge - 5 Problems

💻 Command Output

intermediate

Jenkins Docker Container Startup Output

You run the command to start Jenkins in Docker:

docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts

What output will you see first in the Docker logs indicating Jenkins is ready to use?

Jenkins

docker run -p 8080:8080 -p 50000:50000 jenkins/jenkins:lts

A Error: Port 8080 is already in use

B Jenkins initialAdminPassword: /var/jenkins_home/secrets/initialAdminPassword

C Jenkins is fully up and running

D Jenkins initial setup wizard is complete

💡 Hint

Look for the file path where Jenkins stores the initial admin password.

When Jenkins starts in Docker for the first time, it outputs the location of the initial admin password file. This is shown as 'Jenkins initialAdminPassword: /var/jenkins_home/secrets/initialAdminPassword'.

❓ Configuration

intermediate

Correct Docker Run Command for Jenkins with Volume

Which Docker command correctly runs Jenkins with persistent data stored on the host at /home/user/jenkins_home?

A docker run -p 8080:8080 -v jenkins_home:/var/jenkins_home jenkins/jenkins:lts

B docker run -p 8080:8080 -v /var/jenkins_home:/home/user/jenkins_home jenkins/jenkins:lts

C docker run -p 8080:8080 -v /home/user/jenkins_home:/var/jenkins_home jenkins/jenkins:lts

D docker run -p 8080:8080 -v /home/user/jenkins_home jenkins/jenkins:lts

💡 Hint

Remember the format for Docker volume mapping is host_path:container_path.

Option C correctly maps the host directory to the Jenkins home directory inside the container, ensuring data persists outside the container.

❓ Troubleshoot

advanced

Jenkins Docker Container Fails to Start

You try to start Jenkins with:

docker run -p 8080:8080 jenkins/jenkins:lts

The container exits immediately. What is the most likely cause?

A Port 8080 is already in use on the host

B Docker daemon is not running

C Jenkins image is missing from local Docker cache

D The container requires a volume mount for /var/jenkins_home

💡 Hint

Check if another service is using the port Jenkins needs.

If port 8080 is busy, Docker cannot bind it and the container exits immediately with an error.

🔀 Workflow

advanced

Steps to Upgrade Jenkins Docker Container

What is the correct sequence to upgrade Jenkins running in Docker to a newer version without losing data?

A 1,2,3,4

B 2,3,1,4

C 1,3,2,4

D 2,1,3,4

💡 Hint

You must stop the old container before starting a new one with the updated image.

First stop the old container to free resources, then pull the new image, start a new container with the existing data volume, and finally verify everything works.

✅ Best Practice

expert

Secure Jenkins Docker Installation

Which practice best improves security when running Jenkins in Docker?

A Disable Jenkins authentication to simplify access

B Expose Jenkins ports to all network interfaces

C Run Jenkins container as root user for full access

D Use Docker secrets or environment variables for sensitive data

💡 Hint

Think about how to protect passwords and tokens in Docker.

Using Docker secrets or environment variables keeps sensitive data out of code and images, reducing risk of leaks.