# MinIO Healthcheck

MinIO server exposes three un-authenticated, healthcheck endpoints liveness probe and a cluster probe at `/minio/health/live` and `/minio/health/cluster` respectively.

## Liveness probe

This probe always responds with '200 OK'. Only fails if 'etcd' is configured and unreachable. When liveness probe fails, Kubernetes like platforms restart the container.

```
livenessProbe:
  httpGet:
    path: /minio/health/live
    port: 9000

	Scheme          string
	Online          bool
	lastOnline      time.Time
	lastHCAt        time.Time
	offlineDuration time.Duration
	latency         latencyStat
}

// isOffline returns current liveness result of remote target. Add endpoint to
// healthCheck map if missing and default to online status
func (sys *BucketTargetSys) isOffline(ep *url.URL) bool {
	sys.hMutex.RLock()
	defer sys.hMutex.RUnlock()

## Monitoring MinIO in Kubernetes

MinIO server exposes un-authenticated liveness endpoints so Kubernetes can natively identify unhealthy MinIO containers. MinIO also exposes Prometheus compatible data on a different endpoint to enable Prometheus users to natively monitor their MinIO deployments.

## Explore Further

	op = strings.Replace(op, "ClusterCheckHandler", "health.Cluster", 1)
	op = strings.Replace(op, "ClusterReadCheckHandler", "health.ClusterRead", 1)
	op = strings.Replace(op, "LivenessCheckHandler", "health.Liveness", 1)
	op = strings.Replace(op, "ReadinessCheckHandler", "health.Readiness", 1)
	op = strings.Replace(op, "-fm", "", 1)
	return op
}

// If trace is enabled, execute the request if it is traced by other handlers

	healthCheckClusterPath     = "/cluster"
	healthCheckClusterReadPath = "/cluster/read"
	healthCheckPathPrefix      = minioReservedBucketPath + healthCheckPath
)

// registerHealthCheckRouter - add handler functions for liveness and readiness routes.
func registerHealthCheckRouter(router *mux.Router) {
	// Healthcheck router
	healthRouter := router.PathPrefix(healthCheckPathPrefix).Subrouter()

	// Cluster check handler to verify cluster is active

## Healthcheck Probe

MinIO server has two healthcheck related un-authenticated endpoints, a liveness probe to indicate if server is responding, cluster probe to check if server can be taken down for maintenance.

- Liveness probe available at `/minio/health/live`
- Cluster probe available at `/minio/health/cluster`

var errErasureV3ThisEmpty = fmt.Errorf("Erasure format version 3 has This field empty")

// isServerResolvable - checks if the endpoint is resolvable
// by sending a naked HTTP request with liveness checks.
func isServerResolvable(endpoint Endpoint, timeout time.Duration) error {
	serverURL := &url.URL{
		Scheme: endpoint.Scheme,
		Host:   endpoint.Host,

			}
			return
		}
	}
	writeResponse(w, http.StatusOK, nil, mimeNone)
}

// LivenessCheckHandler checks whether MinIO is up. It differs from the
// readiness handler since a failing liveness check causes pod restarts
// in K8S environments. Therefore, it does not contact external systems.
func LivenessCheckHandler(w http.ResponseWriter, r *http.Request) {
	if objLayer := newObjectLayerFn(); objLayer == nil {

	// Response sender goroutine...
	go func(outBlock <-chan struct{}) {
		wg.Wait()
		defer m.parent.deleteMux(true, m.ID)
		m.sendResponses(ctx, send, c, &handlerErr, outBlock)
	}(m.outBlock)

	// Remote aliveness check if needed.
	if msg.DeadlineMS == 0 || msg.DeadlineMS > uint32(lastPingThreshold/time.Millisecond) {
		go func() {
			wg.Wait()
			m.checkRemoteAlive()
		}()
	}
	return &m
}

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