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Reach a Distroless Container's Debug Endpoint From a Sidecar Container
A distroless container serves a debug interface on its own loopback address. Can you reach this debug endpoint using nothing but standard Docker commands?
Challenges
Focused, hands-on DevOps and server-side problems with hints, feedback, and automated solution checks.
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Run the Application's Test Suite in a Container Without Network Access
You are containerizing the dev workflows of a legacy Python service and you need to find out which external services its test suite talks to. Can you think of an easy way to do it?
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Turn Off a Feature Flag in a Production Redis Server Using a Local Containerized redis-cli
Ad-hoc containers are a handy way to run command-line tools without installing them on the host. Use one to access a production Redis server and turn off a feature flag. But beware of the gotcha: the production server can only be tunneled to the localhost.
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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?
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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.