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Docker 101: Publish All Exposed Ports on Random Host Ports to Avoid Port Conflicts
Can you get several builds of an app running side by side without port conflicts, so you can test them simultaneously?
Challenges
Focused, hands-on problems for sharpening your DevOps and server-side skills. Some teach specific concepts while others mirror real-world scenarios. Every challenge includes hints, feedback, and automated solution checks.
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Secure a Container Registry with Authentication and TLS
Set up your own OCI-compatible container registry with username/password authentication and HTTPS - the kind of protection you'd expect before using a registry in production.
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Run Your Own Container Registry
Stand up a self-hosted container registry so you can push and pull images without relying on a third-party registry. Useful for tests, internal services, air-gapped environments, or just for poking at the OCI Distribution API.
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Transfer Container Images to an Air-Gapped Environment
Get container images onto a server that has no route to the Internet or access to a container registry.
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Inspect a Container Image Without Pulling It
Explore the OCI image index, manifests, and configuration of a remote multi-platform image - without pulling a single byte of filesystem layers into the local Docker daemon.
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A Simple Sandbox Breakout: Spot It and Stop It
Investigate a potentially compromised CI host. A sandboxed "agent" running in the background is suspected of breaking out - confirm the breach and neutralize it without taking the sandbox down.
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Build a Container Image for Another Platform Using a Remote Builder
Learn how to build container images for non-native CPU architectures by offloading the build to a remote machine using Docker Buildx.
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Squash a Bloated Container Image to Remove Waste and Leaked Credentials
A poorly structured Docker image contains leftover build dependencies and leaked private registry credentials hiding in its intermediate layers. Squash the image to produce a clean, compact version with the same runtime filesystem.
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Use Docker Build Arguments to Inject Version and Commit Metadata into a Go Binary
Practice using Docker build arguments to inject version and commit metadata into a Go application during the image build.
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Install a Private npm Package in a Dockerfile Without Leaking Credentials
Build a container image for a Node.js app that uses a private npm package without leaking the registry credentials into the image layers.