What is Docker - Hands-On Activity

What is Docker

📖 Scenario: Imagine you want to share a small app with your friend. But your friend has a different computer setup. Docker helps you package your app so it runs the same everywhere.

🎯 Goal: Learn the basic idea of Docker by creating a simple Dockerfile that sets up a container with a message.

📋 What You'll Learn

Create a Dockerfile with a base image

Add a command to print a message

Build the Docker image

Run the Docker container to see the message

💡 Why This Matters

🌍 Real World

Docker is used to package apps so they run the same on any computer or server, avoiding setup problems.

💼 Career

Knowing Docker is essential for developers and DevOps engineers to build, share, and deploy applications efficiently.

1

Create a Dockerfile with a base image

Create a file named Dockerfile and write the line FROM alpine to use the Alpine Linux base image.

Docker

# Create a Dockerfile with the line: FROM alpine
# Your code here

Need a hint?

Use the FROM instruction to specify the base image.

2

Add a command to print a message

Add the line CMD ["echo", "Hello from Docker!"] below the FROM alpine line in the Dockerfile.

Docker

FROM alpine
# Add a CMD instruction to print "Hello from Docker!"
# Your code here

Need a hint?

Use CMD with JSON array syntax to specify the command.

3

Build the Docker image

Run the command docker build -t hello-docker . in the terminal to build the image named hello-docker from the current directory.

Docker

FROM alpine
CMD ["echo", "Hello from Docker!"]
# Build the Docker image with the tag hello-docker
# Your code here

Need a hint?

Use docker build with -t to name your image.

4

Run the Docker container to see the message

Run the command docker run hello-docker in the terminal to start the container and see the message Hello from Docker!.

Docker

FROM alpine
CMD ["echo", "Hello from Docker!"]
# Command to build image:
docker build -t hello-docker .
# Run the container to see the message
# Your code here

Need a hint?

Use docker run followed by the image name to start the container.