# Observability > Prometheus

# Prometheus

Artillery metrics can be sent to Prometheus via [Pushgateway](https://prometheus.io/docs/instrumenting/pushing/).

## Quick Start

```yaml
config:
  plugins:
    publish-metrics:
      - type: prometheus
        pushgateway: 'http://localhost:9091'
```

## Configuration

* Set `type` to `prometheus` and set `pushgateway` to the URL of the Pushgateway instance
* Set an optional `prefix` (defaults to `artillery`) and `tags`
* You can optionally set a custom CA certificate by using the `ca` option in the config

## Metric Names in Prometheus

Prometheus requires that every metric name is registered ahead of time, whereas metrics can be generated on the fly in Artillery, i.e. there is no way to know all metric names that may be generated by Artillery during a test run ahead of time.

This integration creates three metric names (when using the default `artillery` prefix):

* `artillery_counters`
* `artillery_summaries`
* `artillery_rates`

Individual Artillery metrics are then made available via the `metric` tag. For example:

* The built-in Artillery metric `http.response_time` is of type "summary", i.e. it has the following fields: `min`/`max`/`p95`/`p99`
* Those values can be looked up in Prometheus through the `artillery_summaries` metric with tag `metric:http_response_time_p95` for `p95`

## Examples

### Basic Configuration

```yaml
config:
  plugins:
    publish-metrics:
      - type: prometheus
        pushgateway: 'http://kubernetes.docker.internal:9091'
        tags:
          - 'testId:mytest123'
          - 'type:loadtest'
```

### With Custom Prefix and CA Certificate

```yaml
config:
  plugins:
    publish-metrics:
      - type: prometheus
        pushgateway: 'https://prometheus.example.com:9091'
        prefix: 'loadtest'
        tags:
          - 'environment:production'
          - 'service:checkout'
        ca: |
          -----BEGIN CERTIFICATE-----
          MIIDXTCCAkWgAwIBAgIJAKl...
          -----END CERTIFICATE-----
```

## Best Practices

1. **Use consistent tags**: Include tags that help you filter and group metrics in Prometheus queries
2. **Monitor Pushgateway**: Ensure your Pushgateway instance has sufficient resources to handle the metric volume
3. **Set retention policies**: Configure appropriate retention policies in Prometheus for your load test metrics

## Querying Metrics

Example Prometheus queries:

```promql
# Get 95th percentile response time
artillery_summaries{metric="http_response_time_p95"}

# Get request rate
artillery_rates{metric="http_requests"}

# Get error count
artillery_counters{metric="errors_count"}
```