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]>
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Knowledge Check: Dockerfile and Image Build
1. What does WORKDIR actually set?
Answer: The working directory for every subsequent instruction in the build, and the container's default working directory when it runs.
2. What is the "build context"?
Answer: The directory (usually specified as . at the end of docker build -t tag .) that
Docker can see and copy files FROM during the build — COPY instructions read from it.
3. Why does instruction order in a Dockerfile affect build speed?
Answer: Docker caches each instruction's result as a layer and reuses cached layers for unchanged instructions — everything before the first ACTUALLY-changed instruction stays cached, so putting rarely-changing instructions (like dependency installs) before frequently-changing ones (like application code) minimizes unnecessary rebuilding.
4. What's .dockerignore for, and what other file does it resemble?
Answer: It excludes files from the build context (keeping large/irrelevant files out of the
image and speeding up builds) — the same idea as ROOT 03's .gitignore.
Instructor Notes
Facilitation: Question 3 directly reinforces the caching demo — a good check that the concept, not just the observation, landed.
Approximate timing: 5 minutes.