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