> ## Documentation Index
> Fetch the complete documentation index at: https://docs.ultrabalancer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# /prometheus Endpoint

> Prometheus metrics endpoint with complete metric reference and scraping configuration

## Overview

The `/prometheus` endpoint exports metrics in Prometheus format for native Prometheus scraping and monitoring.

**Endpoint:** `GET /prometheus`

**Response Format:** `text/plain; version=0.0.4`

## Available Metrics

### Request Metrics

```prometheus theme={null}
# HELP ultrabalancer_requests_total Total number of requests
# TYPE ultrabalancer_requests_total counter
ultrabalancer_requests_total 1547823

# HELP ultrabalancer_requests_successful Successful requests
# TYPE ultrabalancer_requests_successful counter
ultrabalancer_requests_successful 1542891

# HELP ultrabalancer_requests_failed Failed requests
# TYPE ultrabalancer_requests_failed counter
ultrabalancer_requests_failed 4932
```

### Response Time Histogram

```prometheus theme={null}
# HELP ultrabalancer_response_time_seconds Response time in seconds
# TYPE ultrabalancer_response_time_seconds histogram
ultrabalancer_response_time_seconds_bucket{le="0.005"} 123456
ultrabalancer_response_time_seconds_bucket{le="0.01"} 234567
ultrabalancer_response_time_seconds_bucket{le="0.025"} 345678
ultrabalancer_response_time_seconds_bucket{le="0.05"} 456789
ultrabalancer_response_time_seconds_bucket{le="0.1"} 512345
ultrabalancer_response_time_seconds_bucket{le="0.25"} 545678
ultrabalancer_response_time_seconds_bucket{le="0.5"} 547123
ultrabalancer_response_time_seconds_bucket{le="1"} 547823
ultrabalancer_response_time_seconds_bucket{le="+Inf"} 1547823
ultrabalancer_response_time_seconds_sum 19247.456
ultrabalancer_response_time_seconds_count 1547823
```

### Backend Metrics

```prometheus theme={null}
# HELP ultrabalancer_backend_healthy Backend health status (1=healthy, 0=unhealthy)
# TYPE ultrabalancer_backend_healthy gauge
ultrabalancer_backend_healthy{backend="192.168.1.10:8080"} 1
ultrabalancer_backend_healthy{backend="192.168.1.11:8080"} 1

# HELP ultrabalancer_backend_requests_total Total requests per backend
# TYPE ultrabalancer_backend_requests_total counter
ultrabalancer_backend_requests_total{backend="192.168.1.10:8080"} 515941
ultrabalancer_backend_requests_total{backend="192.168.1.11:8080"} 515940

# HELP ultrabalancer_backend_active_connections Active connections per backend
# TYPE ultrabalancer_backend_active_connections gauge
ultrabalancer_backend_active_connections{backend="192.168.1.10:8080"} 42
ultrabalancer_backend_active_connections{backend="192.168.1.11:8080"} 38
```

## Prometheus Configuration

```yaml prometheus.yml theme={null}
global:
  scrape_interval: 15s
  evaluation_interval: 15s

scrape_configs:
  - job_name: 'ultrabalancer'
    static_configs:
      - targets: ['localhost:8080']
    metrics_path: '/prometheus'
    scrape_interval: 5s
```

## Common Queries

### Request Rate

```promql theme={null}
# Requests per second
rate(ultrabalancer_requests_total[5m])

# Success rate
100 * (
  rate(ultrabalancer_requests_successful[5m]) /
  rate(ultrabalancer_requests_total[5m])
)

# Error rate
rate(ultrabalancer_requests_failed[5m])
```

### Latency

```promql theme={null}
# Average response time
rate(ultrabalancer_response_time_seconds_sum[5m]) /
rate(ultrabalancer_response_time_seconds_count[5m])

# p50 latency
histogram_quantile(0.50, rate(ultrabalancer_response_time_seconds_bucket[5m]))

# p95 latency
histogram_quantile(0.95, rate(ultrabalancer_response_time_seconds_bucket[5m]))

# p99 latency
histogram_quantile(0.99, rate(ultrabalancer_response_time_seconds_bucket[5m]))
```

## Related Topics

<CardGroup cols={2}>
  <Card title="Metrics Endpoint" icon="code" href="/api-reference/metrics">
    JSON metrics endpoint
  </Card>

  <Card title="Monitoring" icon="display" href="/integration/monitoring">
    Complete monitoring setup
  </Card>

  <Card title="CLI Reference" icon="terminal" href="/configuration/cli-reference">
    Dashboard command documentation
  </Card>
</CardGroup>