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Builds and launches Docker containers with health verification. Use when validating that containerized services start correctly.
Paths: File paths (references/, ../ln-*) are relative to this skill directory. ln-783-container-launcher Type: L3 Worker Category: 7XX Project Bootstrap Purpose Builds Docker images, launches containers, and performs comprehensive health verification using Docker native health checks and retry strategies. Scope: Detect and validate docker-compose.yml configuration Build Docker images Launch containers with proper startup order Verify container health using native health checks Provide access URLs and cleanup instructions Out of Scope: Building application code (handled by ln-781) Running tests (handled by ln-782) Container orchestration beyond single host (Kubernetes, Swarm) When to Use Scenario Use This Skill Standalone-capable Yes Standalone container launch Yes Development environment setup Yes Production deployment No, use proper CI/CD Workflow Step 1: Pre-flight Checks Verify Docker environment readiness. Check Failure Action Docker daemon running Report error with installation instructions Docker Compose available Report error, suggest installation Compose file exists Report error, list expected locations Required ports free Report conflict, suggest alternatives Sufficient disk space Warn if low space (<2GB free) Step 2: Parse Compose Configuration Extract service information from docker-compose.yml. Information Purpose Service names Track which containers to monitor Exposed ports Know which ports to check Health check definitions Use native health checks if defined Dependencies (depends_on) Understand startup order Volume mounts Verify paths exist Step 3: Build Images Build all images defined in compose file. Aspect Strategy Build context Use paths from compose file Build args Pass through from compose configuration Cache Use Docker layer cache for speed Failure Report build errors with full log Step 4: Launch Containers Start containers with proper orchestration. Aspect Strategy Startup order Respect depends_on and healthcheck conditions Detached mode Run in background Network Use compose-defined networks Volumes Mount all defined volumes Step 5: Health Verification Verify all containers are healthy using appropriate strategy. Strategy Selection: Condition Strategy Service has healthcheck: in compose Use native Docker health status Service has depends_on: condition: service_healthy Wait for Docker health status No healthcheck defined Use external HTTP probe with retry Retry Configuration: Parameter Value Rationale Max attempts 10 Allow slow-starting services Initial delay 5s Give containers time to start Backoff Exponential (5, 10, 20, 40s) Avoid overwhelming services Max total wait 120s Reasonable upper limit Health Check Methods: Method When to Use Docker health status When container has healthcheck defined HTTP GET to exposed port For web services without healthcheck Container exec For services without exposed ports TCP port check For databases and message queues Step 6: Report Results Return structured results to orchestrator. Result Structure: Field Description containers Array of container status objects healthChecks Array of health check results accessUrls Map of service name to access URL overallStatus healthy / unhealthy / partial startupDuration Time from launch to all healthy Container Status Object: Field Description name Container name service Service name from compose status running / exited / restarting health healthy / unhealthy / starting / none port Exposed port (if any) startedAt Container start timestamp Health Check Result: Field Description url Checked URL or endpoint status HTTP status code or check result responseTime Time to respond in ms healthy Boolean health status Error Handling Error Type Action Docker daemon not running Report with start instructions Port already in use Report conflict, suggest docker compose down first Image build failed Report with build logs Container exited Report with container logs Health check timeout Report with last known status and logs Network unreachable Check Docker network configuration Options Option Default Description keepRunning true Leave containers running after verification stopAfter false Stop containers after successful verification healthTimeout 120 Max seconds to wait for healthy status showLogs true Show container logs on failure buildFirst true Build images before starting pullLatest false Pull base images before build Cleanup Instructions Provide user with cleanup commands in report. Action Description Stop containers Stop running containers, preserve data Remove containers and networks Clean up containers but keep volumes Remove everything Full cleanup including volumes and images Critical Rules Use native health checks when available - more reliable than external probes Implement retry with backoff - services need time to initialize Always collect logs on failure - essential for debugging Parse compose file for ports - do not hardcode port numbers Respect depends_on order - critical for database-dependent services Monitor Integration (Claude Code 2.1.98+) MANDATORY READ: Load references/monitor_integration_pattern.md For container health verification, use Monitor to stream container logs: Pattern Command timeout_ms Readiness signal docker compose logs -f 2>&1 | grep --line-buffered -iE 'ready|listening|healthy|started' healthTimeout * 1000 Error watch docker compose logs -f 2>&1 | grep --line-buffered -iE 'error|fatal|panic|exit' healthTimeout * 1000 Use persistent: true if keepRunning is true and ongoing log monitoring is needed. Fallback: if Monitor is unavailable, use retry loop with sleep + curl health check. Definition of Done Docker environment verified All images built successfully All containers running All health checks passing Access URLs provided Results returned to orchestrator Reference Files Parent: ../ln-780-bootstrap-verifier/SKILL.md Version: 2.0.0 Last Updated: 2026-01-10
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