Combining RUN commands in Docker - Mini Project: Build & Apply

Combining RUN Commands in Dockerfile

📖 Scenario: You are creating a Docker image for a simple web application. To keep the image small and efficient, you want to combine multiple RUN commands into one.

🎯 Goal: Build a Dockerfile that installs curl and vim using a single RUN command.

📋 What You'll Learn

Create a Dockerfile starting from the ubuntu:20.04 base image

Use a single RUN command to update package lists and install curl and vim

Use apt-get update and apt-get install -y curl vim combined with &&

End the RUN command with rm -rf /var/lib/apt/lists/* to clean up

Print the Dockerfile content at the end

💡 Why This Matters

🌍 Real World

Combining RUN commands in Dockerfiles helps create smaller, faster, and cleaner Docker images used in real-world software deployment.

💼 Career

Understanding how to optimize Dockerfiles is a key skill for DevOps engineers and developers working with containerized applications.

1

Create the base Dockerfile

Create a Dockerfile starting with the line FROM ubuntu:20.04.

Docker

# Your code here

Need a hint?

The first line in a Dockerfile specifies the base image using FROM.

2

Add a combined RUN command

Add a single RUN command that updates the package list with apt-get update and installs curl and vim using apt-get install -y curl vim. Combine these commands using &&.

Docker

FROM ubuntu:20.04
# Add a combined RUN command to update and install curl and vim
# Your code here

Need a hint?

Use RUN apt-get update && apt-get install -y curl vim to combine the commands.

3

Add cleanup to the RUN command

Extend the existing RUN command to also remove the package lists by adding rm -rf /var/lib/apt/lists/* at the end, combined with &&.

Docker

FROM ubuntu:20.04
RUN apt-get update && apt-get install -y curl vim
# Add cleanup command to RUN
# Your code here

Need a hint?

Use && rm -rf /var/lib/apt/lists/* to clean up after installing.

4

Print the Dockerfile content

Write a command to print the content of the Dockerfile using cat Dockerfile.

Docker

# Print the Dockerfile content
# Your code here

Need a hint?

Use cat Dockerfile to display the file content.