Content trust and image signing in Docker - Mini Project: Build & Apply

Content Trust and Image Signing with Docker

📖 Scenario: You work in a team that builds and shares Docker images. To keep your images safe and trusted, you want to use Docker Content Trust. This helps you sign images so others know they are from you and not changed by someone else.

🎯 Goal: Learn how to enable Docker Content Trust, sign a Docker image, and verify the signature to ensure image authenticity.

📋 What You'll Learn

Use Docker commands to enable content trust

Sign a Docker image with a tag

Verify the signed image

Understand the role of environment variables in content trust

💡 Why This Matters

🌍 Real World

Docker Content Trust helps teams ensure that the images they use and share are authentic and have not been tampered with. This is important for security in production environments.

💼 Career

Understanding image signing and content trust is valuable for DevOps engineers and developers working with containerized applications to maintain secure and reliable deployments.

1

Enable Docker Content Trust

Set the environment variable DOCKER_CONTENT_TRUST to 1 to enable Docker Content Trust for your session.

Docker

# Set DOCKER_CONTENT_TRUST=1 to enable content trust
# Your code here

Need a hint?

Use the export command in your terminal to set environment variables.

2

Pull and Tag an Image

Pull the official alpine image from Docker Hub and tag it as myalpine:trusted locally.

Docker

export DOCKER_CONTENT_TRUST=1
# Pull alpine image and tag as myalpine:trusted
# Your code here

Need a hint?

Use docker pull alpine to get the image and docker tag alpine myalpine:trusted to create the new tag.

3

Sign the Docker Image

Push the myalpine:trusted image to your Docker Hub repository to sign it using Docker Content Trust. Use the command docker push myalpine:trusted.

Docker

export DOCKER_CONTENT_TRUST=1

docker pull alpine

docker tag alpine myalpine:trusted
# Push myalpine:trusted to sign the image
# Your code here

Need a hint?

Use docker push with the tagged image name to sign and upload the image.

4

Verify the Signed Image

Run docker pull myalpine:trusted with Docker Content Trust enabled to verify the image signature and confirm it is trusted.

Docker

export DOCKER_CONTENT_TRUST=1

docker pull alpine

docker tag alpine myalpine:trusted

docker push myalpine:trusted
# Pull myalpine:trusted to verify the signature
# Your code here

Need a hint?

Pulling the image again with content trust enabled will check the signature automatically.