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]>
63 lines
1.3 KiB
Markdown
63 lines
1.3 KiB
Markdown
# Demonstration: `run` Creates, `exec` Reaches In
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## OBSERVE
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```
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$ docker run -d --name web nginx:alpine
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$ docker ps --format '{{.Names}}'
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web
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```
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One container exists.
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## HYPOTHESIS
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Predict: will `docker exec web echo hello` create a SECOND container?
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## INSPECT
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```
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$ docker exec web echo hello
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hello
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$ docker ps --format '{{.Names}}'
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web
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```
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Still exactly one container — `exec` ran a new command INSIDE the existing one, it never
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created anything new.
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## CHANGE
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Now actually run the same image again:
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```
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$ docker run -d --name web2 nginx:alpine
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$ docker ps --format '{{.Names}}'
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web2
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web
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```
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Now two containers exist — because `run`, unlike `exec`, always creates a NEW container.
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## VERIFY
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```
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$ docker logs web | tail -3
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$ docker inspect web --format '{{.State.Running}}'
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true
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```
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Both containers are independent, each with their own logs and state — exactly as Module 2's
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"one image, many containers" demonstration showed.
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## Instructor Notes
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**Demo goal:** Directly contrast `run` and `exec`'s effect on the container COUNT — this is the
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most common early confusion and deserves a side-by-side comparison.
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**Approximate timing:** 8 minutes live.
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**Common mistake to watch for:** trying to `exec` into a container that isn't running yet
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(`exec` requires an ALREADY-running target) — a good moment to connect back to `docker ps`
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first.
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