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Luca Sacchi Ricciardi 23a9ffe443 feat(lab-03): complete Phase 4 - Compute & EC2 lab

Phase Plans (5 files):
- 04-RESEARCH.md: Domain research on Docker limits, healthchecks, EC2 parallels
- 04-VALIDATION.md: Success criteria and validation strategy
- 04-01-PLAN.md: Test infrastructure (RED phase)
- 04-02-PLAN.md: Diátxis documentation
- 04-03-PLAN.md: Infrastructure implementation (GREEN phase)

Test Scripts (6 files, 1300+ lines):
- 01-resource-limits-test.sh: Validate INF-03 compliance
- 02-healthcheck-test.sh: Validate healthcheck configuration
- 03-enforcement-test.sh: Verify resource limits with docker stats
- 04-verify-infrastructure.sh: Infrastructure verification
- 99-final-verification.sh: End-to-end student verification
- run-all-tests.sh: Test orchestration with fail-fast
- quick-test.sh: Fast validation (<30s)

Documentation (11 files, 2500+ lines):
Tutorials (3):
- 01-set-resource-limits.md: EC2 instance types, Docker limits syntax
- 02-implement-healthchecks.md: ELB health check parallels
- 03-dependencies-with-health.md: depends_on with service_healthy

How-to Guides (4):
- check-resource-usage.md: docker stats monitoring
- test-limits-enforcement.md: Stress testing CPU/memory
- custom-healthcheck.md: HTTP, TCP, database healthchecks
- instance-type-mapping.md: Docker limits → EC2 mapping

Reference (3):
- compose-resources-syntax.md: Complete deploy.resources reference
- healthcheck-syntax.md: All healthcheck parameters
- ec2-instance-mapping.md: Instance type mapping table

Explanation (1):
- compute-ec2-parallels.md: Container=EC2, Limits=Instance Type, Healthcheck=ELB

Infrastructure:
- docker-compose.yml: 5 services (web, app, worker, db, stress-test)
  All services: INF-03 compliant (cpus + memory limits)
  All services: healthcheck configured
  EC2 parallels: t2.nano, t2.micro, t2.small, t2.medium, m5.large
- Dockerfile: Alpine 3.19 + stress tools + non-root user

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

2026-04-03 15:16:58 +02:00

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Reference: Docker Compose Healthcheck Syntax

Riferimento completo per la configurazione degli healthchecks.

Sezione healthcheck

Struttura Completa

services:
  service_name:
    healthcheck:
      test: ["CMD", "command", "arg1", "arg2"]
      interval: 30s
      timeout: 30s
      retries: 3
      start_period: 0s

Parametri

test (Required)

Comando da eseguire per verificare la salute.

Formato CMD:

test: ["CMD", "wget", "--spider", "-q", "http://localhost/health"]

Formato CMD-SHELL:

test: ["CMD-SHELL", "curl -f http://localhost/ || exit 1"]

Formato NONE:

test: ["NONE"]

Disabilita healthcheck ereditato dall'immagine.

interval

Frequenza di esecuzione del test.

interval: 5s       # Ogni 5 secondi
interval: 10s      # Ogni 10 secondi
interval: 30s      # Ogni 30 secondi (default)
interval: 1m       # Ogni minuto

Validità:

Minimo: 1s (1 secondo)
Massimo: Nessuno
Default: 30s

timeout

Tempo massimo per completare il test.

timeout: 2s        # 2 secondi
timeout: 5s        # 5 secondi (default)
timeout: 30s       # 30 secondi

Nota: Se il test supera il timeout, conta come fallimento.

retries

Numero di fallimenti consecutivi prima di marcare unhealthy.

retries: 1         # 1 fallimento = unhealthy
retries: 3         # 3 fallimenti = unhealthy (default)
retries: 5         # 5 fallimenti = unhealthy

Calcolo del tempo unhealthy:

tempo_totale = (interval + timeout) × retries

Esempio con interval: 10s, timeout: 5s, retries: 3:

Check 1: 0s - 5s
Check 2: 10s - 15s
Check 3: 20s - 25s
Unhealthy dopo: 25s

start_period

Grace period prima di contare retries verso unhealthy.

start_period: 0s   # Nessun grace period (default)
start_period: 5s   # 5 secondi di grace
start_period: 10s  # 10 secondi di grace
start_period: 30s  # 30 secondi di grace

Comportamento:

Durante start_period: Fallimenti non contano
Dopo start_period: retries inizi a contare

Esempi per Tipo di Servizio

HTTP Service (Nginx)

healthcheck:
  test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost/"]
  interval: 10s
  timeout: 5s
  retries: 3
  start_period: 5s

Database (PostgreSQL)

healthcheck:
  test: ["CMD-SHELL", "pg_isready -U postgres || exit 1"]
  interval: 10s
  timeout: 5s
  retries: 5
  start_period: 10s

Cache (Redis)

healthcheck:
  test: ["CMD", "redis-cli", "ping"]
  interval: 10s
  timeout: 3s
  retries: 3

TCP Connection

healthcheck:
  test: ["CMD-SHELL", "nc -z localhost 8080 || exit 1"]
  interval: 15s
  timeout: 2s
  retries: 3

File Check

healthcheck:
  test: ["CMD-SHELL", "test -f /tmp/ready || exit 1"]
  interval: 5s
  timeout: 1s
  retries: 5

Stati di Salute

Ciclo di Vita

created → starting → healthy
                ↓
              unhealthy

Transizioni:

Da	A	Condizione
created	starting	Container avviato con healthcheck
starting	healthy	`retries` consecutivi passano
starting	unhealthy	`retries` consecutivi falliscono (dopo start_period)
healthy	unhealthy	`retries` consecutivi falliscono
unhealthy	healthy	1 check passa

Ispezionare Stato

# Stato corrente
docker inspect lab03-web --format '{{.State.Health.Status}}'
# Output: healthy / unhealthy / starting

# Exit code dell'ultimo check
docker inspect lab03-web --format '{{.State.Health.ExitCode}}'
# Output: 0 (success) o !0 (failure)

### Vedi Anche
- Tutorial: Implementare Healthchecks
- How-to: Custom Healthcheck

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