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]>
1.5 KiB
Demonstration: One Image, Many Independent Containers
OBSERVE
$ docker images | grep alpine
alpine 3.19 a1b2c3d4e5f6 2 weeks ago 7.4MB
Exactly one alpine:3.19 image exists locally right now.
HYPOTHESIS
Predict: after running three containers from it, how many images will docker images show?
INSPECT
$ docker run -d --name c1 alpine:3.19 sleep 300
$ docker run -d --name c2 alpine:3.19 sleep 300
$ docker run -d --name c3 alpine:3.19 sleep 300
$ docker images | grep alpine
alpine 3.19 a1b2c3d4e5f6 2 weeks ago 7.4MB
Still exactly one image — confirmed.
CHANGE
$ docker ps --format '{{.Names}}: {{.ID}}'
c3: 9f8e7d6c5b4a
c2: 3d2c1b0a9f8e
c1: 7c6b5a4d3e2f
Three DIFFERENT containers, each with its own ID, all created from that same one image.
VERIFY
$ docker rm -f c1 c2 c3
$ docker images | grep alpine
alpine 3.19 a1b2c3d4e5f6 2 weeks ago 7.4MB
Removing all three containers left the image completely untouched — proving containers and the image they came from have independent lifecycles.
Instructor Notes
Demo goal: Make the 1-image-many-containers relationship undeniable by actually counting both before and after, rather than just stating it.
Approximate timing: 8 minutes live.
Common mistake to watch for: assuming docker rm on a container also removes its image —
a good moment to reinforce that images and containers have separate removal commands
(docker rm for containers, docker rmi for images) for exactly this reason.