# Monitor Endpoints

Track custom metrics from your deployment endpoints by printing JSON metadata. Valohai automatically collects and visualizes these metrics.

### Collect metrics

Print JSON with `vh_metadata` to log metrics from your endpoint:

```python
import json

print(
    json.dumps(
        {
            "vh_metadata": {
                "accuracy": 0.9247,
                "best_guess": "dog",
                "confidence": 0.87,
            },
        },
    ),
)
```

Valohai parses this output and makes it available for visualization.

### View metrics

Access deployment metrics from your deployment version:

1. Open the **Deployment** tab
2. Select your deployment
3. Click on a version
4. View metrics in the **Monitoring** tab

**Available visualizations:**

* Time series charts (metrics over time)
* Histograms (distribution of values)
* Request logs (individual predictions)

### Common metrics to track

**Model performance:**

```python
print(
    json.dumps(
        {
            "vh_metadata": {
                "prediction_confidence": 0.94,
                "processing_time_ms": 23,
            },
        },
    ),
)
```

**Business metrics:**

```python
print(
    json.dumps(
        {
            "vh_metadata": {
                "fraud_detected": True,
                "transaction_amount": 1250.00,
            },
        },
    ),
)
```

**System metrics:**

```python
import time

start = time.time()
# ... inference code ...
duration = time.time() - start

print(
    json.dumps(
        {
            "vh_metadata": {
                "inference_latency_ms": int(duration * 1000),
            },
        },
    ),
)
```

### View endpoint logs

Access full logs for debugging or detailed inspection:

1. Navigate to your deployment version
2. Select an endpoint
3. Click **Log** tab
4. Filter by time range or search for specific events

***

**Next:** Learn how to [troubleshoot failing endpoints](https://github.com/valohai/dokuhai/blob/main/docs/debug.md).


---

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