ced4568andClaude Sonnet 5
682ef2de47
Adds all 8 ROOT 04 modules (why containers exist, images & containers, Docker CLI, container networking, container storage, Dockerfile & image build, Docker Compose, containers → Kubernetes) — 43 activities, using the nested Docker Engine Phase 6D built and tested. Modules 1, 2, and 8 are conceptual (no lab by design) — the honest bridge module (M8) explicitly names what Kubernetes adds beyond what this course already taught, without re-teaching Kubernetes itself. Adds 5 new hands-on Docker scenarios plus 2 MCQs, all against the real nested Docker Engine: docker-cli-basics (run/exec/inspect a real container), docker-container-networking (a genuine "works internally, unreachable from host" port-publishing failure, diagnosed and fixed by recreating the container with the correct `-p` flag), docker-container-storage (a real destroy/recreate cycle proving named-volume persistence, not just described), docker-build-image (a real Dockerfile, a real build, a real custom image run), and docker-compose-multiservice (a real two-service Compose application with a real published port). All tested end-to-end via the real scenario-validation API, including negative tests. Wires rootnode-containers-assessment (2 required + 4 random-draw scenarios) using the existing Phase 3B assessment engine. This completes the entire ROOT_ Foundations sequence (ROOT 01-04) — see docs/PHASE6E_ROOT_FOUNDATIONS_COMPLETION.md. Co-Authored-By: Claude Sonnet 5 <[email protected]>
34 lines
1.2 KiB
Markdown
34 lines
1.2 KiB
Markdown
# Knowledge Check: Why Containers Exist
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---
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**1. What real problem does "it works on my machine" name?**
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*Answer:* Dependency/environment inconsistency between where an application was developed and
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where it actually needs to run — differences in libraries, versions, and configuration that are
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easy to overlook and hard to fully document by hand.
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---
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**2. What's the actual architectural difference between a container and a virtual machine, not
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just "containers are smaller"?**
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*Answer:* A container shares the host machine's kernel and only isolates the application's
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process/filesystem/network view. A VM virtualizes an entire computer, including running its own
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separate kernel — a genuinely different isolation model, not just a size difference.
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---
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**3. Why do containers start so much faster than VMs?**
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*Answer:* A container doesn't boot a separate operating system/kernel — it starts a process
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using the ALREADY-RUNNING host kernel, while a VM has to boot an entire independent OS from
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scratch.
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## Instructor Notes
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**Facilitation:** Question 2 is the one worth confirming explicitly — many students carry the
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misconception "container = tiny VM" past this point without correction.
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**Approximate timing:** 5 minutes.
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