Why Docker in CI/CD matters - See It in Action

Why Docker in CI/CD Matters

📖 Scenario: You work in a team that builds software applications. Your team wants to make sure the software is tested and delivered quickly and reliably. To do this, you use a process called CI/CD (Continuous Integration and Continuous Delivery). Docker helps your team by making sure the software runs the same way everywhere.

🎯 Goal: You will create a simple Docker setup to understand why Docker is important in CI/CD pipelines. You will create a Dockerfile, add a configuration variable, build the Docker image, and finally run the container to see the output.

📋 What You'll Learn

Create a Dockerfile with a base image and a simple command

Add an environment variable in the Dockerfile

Build the Docker image using the correct tag

Run the Docker container and display the output

💡 Why This Matters

🌍 Real World

Teams use Docker in CI/CD pipelines to avoid 'it works on my machine' problems by packaging apps with all dependencies.

💼 Career

Understanding Docker in CI/CD is essential for DevOps roles to automate testing and deployment reliably.

1

Create a Dockerfile with a base image

Create a file named Dockerfile with the base image alpine:latest and a command to print Hello from Docker in CI/CD! using echo.

Docker

# Create a Dockerfile with base image alpine:latest and echo command
# Your code here

Need a hint?

Use FROM alpine:latest to set the base image. Use CMD ["echo", "Your message"] to print a message.

2

Add an environment variable in the Dockerfile

Add an environment variable called GREETING with the value Hello from Docker in CI/CD! in the Dockerfile. Change the CMD to use this variable with sh -c and echo.

Docker

FROM alpine:latest
# Add environment variable GREETING
ENV GREETING="Hello from Docker in CI/CD!"
# Change CMD to use GREETING variable
CMD ["sh", "-c", "echo $GREETING"]

Need a hint?

Use ENV GREETING="Hello from Docker in CI/CD!" to set the variable. Use CMD ["sh", "-c", "echo $GREETING"] to print it.

3

Build the Docker image with a tag

Build the Docker image using the command docker build -t ci-cd-demo . in the terminal. This tags the image as ci-cd-demo.

Docker

FROM alpine:latest
ENV GREETING="Hello from Docker in CI/CD!"
CMD ["sh", "-c", "echo $GREETING"]
# Build the image with tag ci-cd-demo
# Your code here

Need a hint?

Use docker build -t ci-cd-demo . to build the image with the tag ci-cd-demo.

4

Run the Docker container and display the output

Run the Docker container using docker run ci-cd-demo and print the output.

Docker

FROM alpine:latest
ENV GREETING="Hello from Docker in CI/CD!"
CMD ["sh", "-c", "echo $GREETING"]
# Run the container and print output
# Your code here

Need a hint?

Use docker run ci-cd-demo to run the container and see the message.