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]>
23 lines
1.4 KiB
JSON
23 lines
1.4 KiB
JSON
{
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"id": "docker-port-publish-mcq",
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"title": "Works Inside, Unreachable Outside",
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"category": "Containers",
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"isolation_type": "shared_namespace",
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"difficulty": "Medium",
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"type": "mcq",
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"weight": 4,
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"description": "## Works Inside, Unreachable Outside\n\nA web server container is confirmed healthy — `docker exec <container> curl localhost:80` succeeds from inside it. But `curl http://localhost:8080/` from the HOST fails to connect. The container was started with plain `docker run -d myapp` (no other flags). What's most likely missing?",
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"options": [
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{ "id": "a", "text": "The image itself is broken" },
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{ "id": "b", "text": "A `-p 8080:80` port-publish flag was never set when the container was created, so nothing on the host maps to the container's port 80" },
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{ "id": "c", "text": "The container needs more memory" },
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{ "id": "d", "text": "DNS is misconfigured" }
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],
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"correct_option": "b",
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"explanation": "Working correctly INSIDE the container proves the application itself is fine — the failure is specifically that the host has no mapping to the container's internal port. Port publishing (`-p hostPort:containerPort`) must be set at container creation time; without it, the container's ports are only reachable from other containers on the same Docker network, never from the host.",
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"hints": [],
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"setup_commands": [],
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"default_namespace": "default",
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"teardown_commands": []
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}
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