# health

Stdlib `http.Handler` for service health checks. Runs all checks concurrently and returns a JSON summary.

## Install

```
go get code.nochebuena.dev/go/health
```

## Usage

```go
handler := health.NewHandler(logger, db, cache, queue)
r.Get("/health", handler)
```

### Response

```json
{
  "status": "UP",
  "components": {
    "db":    {"status": "UP",   "latency": "1.2ms"},
    "cache": {"status": "DOWN", "latency": "5ms", "error": "connection refused"}
  }
}
```

| Overall status | HTTP code | Condition |
|---|---|---|
| `UP` | 200 | All checks pass |
| `DEGRADED` | 200 | One or more `LevelDegraded` checks fail; no critical failures |
| `DOWN` | 503 | One or more `LevelCritical` checks fail |

## Implementing `Checkable`

```go
func (d *DB) HealthCheck(ctx context.Context) error { return d.pool.PingContext(ctx) }
func (d *DB) Name() string                          { return "postgres" }
func (d *DB) Priority() health.Level                { return health.LevelCritical }
```

## Logger

`health.Logger` is a duck-typed interface satisfied by `logz.Logger` without importing it.

```go
type Logger interface {
    Debug(msg string, args ...any)
    Info(msg string, args ...any)
    Warn(msg string, args ...any)
    Error(msg string, err error, args ...any)
    WithContext(ctx context.Context) Logger
}
```