{
  "id": "docker-compose-multiservice",
  "title": "Run a Real Two-Service Application With Compose",
  "category": "Containers",
  "isolation_type": "shared_namespace",
  "difficulty": "Medium",
  "type": "task",
  "weight": 7,
  "description": "## Run a Real Two-Service Application With Compose\n\nManually running two related containers, wiring their network, and keeping track of dependency order gets tedious fast — Compose describes the whole application in one file.\n\n**Your task**, at `/srv/compose-lab/docker-compose.yml`:\n\n1. Define a `web` service from `nginx:alpine`, publishing host port `8077` to container port `80`\n2. Define an `api` service from `alpine:3.19`, running `sh -c 'echo api-ready > /tmp/ready && sleep 3600'`\n3. Make `web` depend on `api` (`depends_on`)\n4. Bring the whole application up with `docker compose up -d`\n5. Confirm both services are actually running, and that `curl http://localhost:8077/` succeeds",
  "hints": [
    {
      "title": "The compose file",
      "body": "A `services:` block defines each container as a named service — `ports` publishes a port exactly like `docker run -p`, `depends_on` controls startup order.",
      "command": "cat <<EOF > /srv/compose-lab/docker-compose.yml\nservices:\n  web:\n    image: nginx:alpine\n    ports:\n      - '8077:80'\n    depends_on:\n      - api\n  api:\n    image: alpine:3.19\n    command: sh -c 'echo api-ready > /tmp/ready && sleep 3600'\nEOF"
    },
    {
      "title": "Bringing it up",
      "body": "`docker compose up -d` reads the compose file in the current directory (or use `-f` to point at one elsewhere) and starts every service defined in it.",
      "command": "cd /srv/compose-lab && docker compose up -d"
    }
  ],
  "setup_commands": [
    { "command": "rm -rf /srv/compose-lab && mkdir -p /srv/compose-lab" },
    { "command": "docker pull nginx:alpine" },
    { "command": "docker pull alpine:3.19" }
  ],
  "validation": {
    "commands": [
      { "description": "the web service is running", "command": "docker compose -f /srv/compose-lab/docker-compose.yml ps --format '{{.Service}}:{{.State}}' 2>/dev/null | grep web", "expected_output": "web:running", "match": "exact" },
      { "description": "the api service is running", "command": "docker compose -f /srv/compose-lab/docker-compose.yml ps --format '{{.Service}}:{{.State}}' 2>/dev/null | grep api", "expected_output": "api:running", "match": "exact" },
      { "description": "the published port actually works", "command": "curl -sf http://localhost:8077/ -o /dev/null -w '%{http_code}'", "expected_output": "200", "match": "exact" }
    ]
  },
  "default_namespace": "default",
  "teardown_commands": [
    { "command": "docker compose -f /srv/compose-lab/docker-compose.yml down 2>/dev/null; rm -rf /srv/compose-lab" }
  ]
}