Create Health Check

Health Check Generator

Creates Health Check infrastructure for monitoring application and dependency health.

When to Use

Component Characteristics

HealthCheckInterface

• name(): string — unique identifier for the check
• check(): HealthCheckResult — execute the health check

HealthStatus Enum

• Healthy: All systems operational
• Degraded: Partially operational, non-critical issues
• Unhealthy: System is down or critical failure

HealthCheckResult

• Immutable value object
• Properties: name, status (HealthStatus), durationMs (float), details (array)
• Static factory methods: healthy(), unhealthy(), degraded()

HealthCheckRunner

• Accepts iterable of HealthCheckInterface implementations
• Runs all checks with configurable timeout
• Aggregates overall status (worst status wins)
• Catches exceptions as unhealthy results

Generation Process

Step 1: Generate Domain Components

Path: src/Domain/Shared/Health/

1. HealthCheckInterface.php — Interface for health checks
2. HealthStatus.php — Enum with Healthy/Degraded/Unhealthy states
3. HealthCheckResult.php — Immutable result value object

Step 2: Generate Infrastructure Checkers

Path: src/Infrastructure/Health/

1. DatabaseHealthCheck.php — PDO connectivity check
2. RedisHealthCheck.php — Redis connectivity check
3. RabbitMqHealthCheck.php — RabbitMQ connectivity check
4. HealthCheckRunner.php — Runs all checks and aggregates status

Step 3: Generate Presentation Endpoint

Path: src/Presentation/Api/Action/

1. HealthCheckAction.php — PSR-15 handler returning JSON response

Step 4: Generate Tests

1. HealthCheckResultTest.php — Result construction and serialization
2. HealthCheckRunnerTest.php — Aggregation and error handling
3. HealthCheckActionTest.php — HTTP response codes and format

File Placement

Naming Conventions

Quick Template Reference

HealthCheckInterface

interface HealthCheckInterface
{
    public function name(): string;
    public function check(): HealthCheckResult;
}

HealthStatus

enum HealthStatus: string
{
    case Healthy = 'healthy';
    case Degraded = 'degraded';
    case Unhealthy = 'unhealthy';

    public function isOperational(): bool;
    public function merge(self $other): self;
}

HealthCheckResult

final readonly class HealthCheckResult
{
    public function __construct(
        public string $name,
        public HealthStatus $status,
        public float $durationMs,
        public array $details = []
    ) {}

    public static function healthy(string $name, float $durationMs): self;
    public static function unhealthy(string $name, float $durationMs, string $error): self;
    public static function degraded(string $name, float $durationMs, string $reason): self;
    public function toArray(): array;
}

Usage Example

// GET /health
$runner = new HealthCheckRunner($checkers, timeoutSeconds: 5);
$result = $runner->run();
// $result['status'] is HealthStatus, $result['checks'] is array<string, HealthCheckResult>

Response Format (RFC Health Check JSON)

{
    "status": "healthy",
    "checks": {
        "database": {
            "name": "database",
            "status": "healthy",
            "duration_ms": 1.23,
            "details": {}
        },
        "redis": {
            "name": "redis",
            "status": "healthy",
            "duration_ms": 0.45,
            "details": {}
        },
        "rabbitmq": {
            "name": "rabbitmq",
            "status": "degraded",
            "duration_ms": 15.7,
            "details": {
                "reason": "High latency detected"
            }
        }
    }
}

Anti-patterns to Avoid

References

For complete PHP templates and examples, see:

• references/templates.md — HealthCheckInterface, HealthStatus, HealthCheckResult, checkers, runner, action templates
• references/examples.md — DI wiring, custom checker, and unit tests

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