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]>
65 lines
1.7 KiB
Markdown
65 lines
1.7 KiB
Markdown
# Demonstration: One File, Two Containers, One Network — Automatically
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## OBSERVE
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```yaml
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services:
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web:
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image: nginx:alpine
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ports:
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- "8080:80"
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cache:
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image: redis:alpine
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```
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## HYPOTHESIS
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Predict: without running `docker network create` yourself, will `web` be able to reach `cache`
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by name after `docker compose up`?
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## INSPECT
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```
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$ docker compose up -d
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$ docker compose exec web sh -c "wget -qO- http://cache:6379/ 2>&1 | head -1"
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```
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(Redis doesn't speak HTTP, so this specific request looks odd, but the connection ITSELF
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succeeding or failing tells you whether name resolution and network reachability work — a
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`Connection refused` here would mean it REACHED `cache` but Redis rejected the protocol
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mismatch, which is actually proof the network worked.)
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## CHANGE
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```
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$ docker compose ps
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NAME IMAGE STATUS
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web-1 nginx:alpine Up
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cache-1 redis:alpine Up
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$ docker network ls | grep compose
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xyz123 myproject_default bridge
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```
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Compose created a network automatically, named after the project directory, with no manual step.
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## VERIFY
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```
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$ docker compose down
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$ docker network ls | grep compose
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(nothing)
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```
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`docker compose down` cleaned up EVERYTHING Compose created — containers AND the network — in
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one command.
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## Instructor Notes
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**Demo goal:** Show the automatic networking as a real, observable fact (a real network exists,
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named and scoped to the project) rather than an assumed convenience.
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**Approximate timing:** 8 minutes live.
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**Common mistake to watch for:** forgetting `docker compose down` and accumulating orphaned
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networks/containers across multiple exercises — a good habit to reinforce explicitly.
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