Scratch base image for minimal containers in Docker - Mini Project: Build & Apply

Scratch Base Image for Minimal Containers

📖 Scenario: You want to create a very small Docker container that runs a simple program without any extra files or tools. Using the scratch base image helps you build the smallest possible container.This is useful when you want your container to be lightweight and secure, like sending a small package instead of a big box.

🎯 Goal: Build a Docker image using the scratch base image that runs a simple static binary program.You will create a Dockerfile step-by-step to copy your program into the container and run it.

📋 What You'll Learn

Create a Dockerfile starting from the scratch base image

Copy a static binary file named hello into the container

Set the container to run the hello program when started

Build and run the container to see the output

💡 Why This Matters

🌍 Real World

Using the scratch base image helps create very small and secure containers by including only the necessary files. This is useful for production environments where size and security matter.

💼 Career

Many DevOps and cloud engineering roles require building efficient container images. Knowing how to use scratch images is a valuable skill for optimizing container deployments.

1

Create a Dockerfile with the scratch base image

Create a file named Dockerfile and write the line FROM scratch as the first line to use the minimal base image.

Docker

# Your code here

Need a hint?

The FROM instruction sets the base image. Use scratch for an empty base.

2

Copy the static binary into the container

Add a line to the Dockerfile to copy the file named hello from your current directory into the container's root directory /.

Docker

FROM scratch
# Your code here

Need a hint?

Use the COPY instruction to add files into the container.

3

Set the container to run the binary

Add a line to the Dockerfile to set the default command to run the hello program when the container starts. Use the CMD instruction with the executable path /hello.

Docker

FROM scratch
COPY hello /
# Your code here

Need a hint?

The CMD instruction defines the command to run inside the container.

4

Build and run the Docker container

Build the Docker image with the tag hello-scratch using the command docker build -t hello-scratch .. Then run the container with docker run --rm hello-scratch to see the output.

Docker

FROM scratch
COPY hello /
CMD ["/hello"]
# Your code here

Need a hint?

Make sure your hello binary prints Hello from scratch! when run.