---
title: "Metrics"
description: "Enable and consume OpenTelemetry & vendor specific metrics"
---

We provide metrics in the **OpenTelemetry** (OTel) format and additionally support the following vendor backends:

* **Prometheus** (native scrape and via OTel Collector)

## Why Metrics & OTel

Observability enables:

1. **Incident detection** (latency spikes, reconnect storms)
2. **Capacity planning** (bytes, active sessions)
3. **User‑experience SLAs** (p95 tunnel latency, auth latency)
4. **Faster RCA** (dimensions like `error_type`, `result`)

OpenTelemetry provides a **vendor‑neutral** pipeline so you can change backends without retouching instrumented code.

## Availability

Newt exposes metrics starting from specific releases, but metrics are disabled in their default configuration.

- Newt: metrics implemented since Newt 1.6.0 (disabled by default)

## Open Telemetry

Push metrics and traces to an **OTel Collector** or any backend that accepts OTLP.

<Tip>
If you only enable Prometheus scrape, leave `*_METRICS_OTLP_ENABLED=false` and omit OTLP vars.
</Tip>

<Note>
The OTel Collector commonly uses port <code>4317</code> for gRPC and <code>4318</code> for HTTP. Set <code>OTEL_EXPORTER_OTLP_PROTOCOL</code> to <code>http/protobuf</code> for HTTP or <code>grpc</code> for gRPC, and point <code>OTEL_EXPORTER_OTLP_ENDPOINT</code> accordingly.
For further customization, see the [OTel Collector documentation](https://opentelemetry.io/docs/collector/).
</Note>

<AccordionGroup>
<Accordion title="Newt Configuration">
<Tabs>
	<Tab title="Environment Variables">
		```text
		NEWT_METRICS_OTLP_ENABLED=true         # enable OTLP exporter
		OTEL_EXPORTER_OTLP_ENDPOINT=otel-collector:4317
		OTEL_EXPORTER_OTLP_INSECURE=true       # or false + TLS vars
		OTEL_METRIC_EXPORT_INTERVAL=15s
		# Optional auth / TLS
		OTEL_EXPORTER_OTLP_HEADERS=authorization=Bearer%20XYZ
		OTEL_EXPORTER_OTLP_CERTIFICATE=/etc/otel/ca.pem
		```
	</Tab>
  	<Tab title="CLI Args">
		```text
		newt \
			--metrics-otlp-enabled=true \ # alias for otel
			--otel=true \
			--otel-exporter-otlp-endpoint=otel-collector:4317 \
			--otel-exporter-otlp-insecure=true \
			--otel-metric-export-interval=15s \
			--otel-exporter-otlp-headers=authorization=Bearer%20XYZ \
			--otel-exporter-otlp-certificate=/etc/otel/ca.pem
		```
	 See the [CLI reference](../../manage/sites/configure-site) for all available flags.
	</Tab>
</Tabs>
</Accordion>

<Accordion title="Newt Configuration Examples">
<Tabs>
  <Tab title="CLI (gRPC)">

		```bash
		# Enable OTLP exporters and point to your Collector's gRPC receiver.
		export OTEL_EXPORTER_OTLP_ENDPOINT="http://localhost:4317"
		export OTEL_EXPORTER_OTLP_PROTOCOL="grpc"

		newt \
		--otlp=true
		--id saz281jfa8z37zg
		--secret ssfdfsder33rrerrwe
		--endpoint http://pangolin.example.com
		```

  </Tab>
  <Tab title="Docker Compose">

		```yaml title="docker-compose.metrics.yaml"
		services:
			otel-collector:
				image: ghcr.io/open-telemetry/opentelemetry-collector-releases/opentelemetry-collector-contrib:latest # DO NOT use 'latest' in production
				command: ["--config=/etc/otel/config.yaml"]
				volumes:
					- ./otel-config.yaml:/etc/otel/config.yaml:ro
				ports:
				- "4317:4317"   # gRPC
				- "4318:4318"   # HTTP
				- "8888:8888"   # Prometheus exporter (from the Collector) - Optional

			newt:
				image: fosrl/newt:latest # DO NOT use 'latest' in production
				environment:
					NEWT_METRICS_OTLP_ENABLED: "true"
					OTEL_EXPORTER_OTLP_ENDPOINT: otel-collector:4317
					OTEL_EXPORTER_OTLP_INSECURE: "true"
					PANGOLIN_ENDPOINT: https://example.com
					NEWT_ID: heresmynewtid
					NEWT_SECRET: yoursupersecretkeyhere
		```

		```yaml title="otel-config.yaml"
		receivers:
		otlp:
			protocols:
			grpc:
				endpoint: 0.0.0.0:4317
			http:
				endpoint: 0.0.0.0:4318

		processors: {}

		# Example exporters:
		exporters:
			otlp:
				endpoint: otel-collector:4317
				insecure: true
			prometheus:
				endpoint: "0.0.0.0:8889"

		service:
		pipelines:
			metrics:
			receivers: [otlp]
			processors: []
			exporters: [prometheus]
		```

		Forward to Remote Write Backend

		```yaml title="otel-config-remote.yaml"
		exporters:
			prometheusremotewrite:
				endpoint: https://prom-remote.example.com/api/v1/write
				headers:
					X-Scope-OrgID: tenant-a
				tls:
					insecure_skip_verify: false
		service:
			pipelines:
				metrics/remote:
					receivers: [otlp]
					processors: [batch]
					exporters: [prometheusremotewrite]
		```
		<Note>
		Combine exporters (e.g. local Prometheus + remote write) to retain fast local dashboards and ship long‑term retention externally.
		</Note>

	</Tab>
</Tabs>
</Accordion>
</AccordionGroup>


## Prometheus (without OTel Collector)

<AccordionGroup>
<Accordion title="Newt Configuration">

Each service listens on an admin HTTP address (example Newt default `:2112`).

<Tabs>
	<Tab title="Environment Variables">
		```text
		NEWT_METRICS_PROMETHEUS_ENABLED=true   # /metrics endpoint
		NEWT_ADMIN_ADDR=:2112                  # admin HTTP address
		```
	</Tab>
  	<Tab title="CLI Args">
		```text
		newt \
			--metrics-prometheus-enabled=true \ # alias for metrics
			--metrics=true
			--admin-addr=:2112 \
		```
	 See the [CLI reference](../../manage/sites/configure-site) for all available flags.
	</Tab>
</Tabs>
</Accordion>

<Accordion title="Newt Configuration Examples">
<Tabs>
	<Tab title="CLI">
		```bash
		newt \
			--metrics-prometheus-enabled=true \
			--admin-addr=:2112 \
			--id saz281jfa8z37zg \
			--secret ssfdfsder33rrerrwe \
			--endpoint https://pangolin.example.com
		```
	</Tab>
	<Tab title="Docker Compose">
  		```yaml title="docker-compose.metrics.yaml"
		services:
			newt:
				image: fosrl/newt:latest # DO NOT use 'latest' in production
				environment:
					NEWT_METRICS_OTLP_ENABLED: "true"
					OTEL_EXPORTER_OTLP_ENDPOINT: otel-collector:4317
					OTEL_EXPORTER_OTLP_INSECURE: "true"
					PANGOLIN_ENDPOINT: https://example.com
					NEWT_ID: saz281jfa8z37zg
					NEWT_SECRET: ssfdfsder33rrerrwe
		```
	</Tab>
	<Tab title="Prometheus Scrape Config">
		```yaml title="prometheus.yml (fragment)"
		scrape_configs:
			- job_name: pangolin
				static_configs: [{ targets: ["pangolin:2112"] }]
		```
	</Tab>
</Tabs>
</Accordion>
</AccordionGroup>

## Full Metric Reference

**Version 1.0.0 from 2025-10-28**

Below are currently implemented metrics for **Newt**.

* **Metric**: exact metric name
* **Instrument & unit**: OTel instrument type and canonical unit
* **Purpose**: what the metric conveys / recommended use
* **Emission path**: subsystem responsible (for troubleshooting missing data)
* **Example series**: representative sample including labels

<Warning>
Names/labels can change between major versions. Avoid hard‑coding full label sets in alerts; prefer existence checks and aggregate functions.
</Warning>

### Newt metrics

<Tabs>
  <Tab title="OpenTelemetry (OTel)">
    <ResponseField name="newt">
      OpenTelemetry metric instruments exposed by Newt. Expand each section to see individual metrics with labels, units, emission points, and examples.

      <Expandable title="Site & Build">
        <ResponseField name="newt_site_registrations_total" type="Counter">
          Counts Pangolin registration attempts keyed by result.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `result` (`success`|`failure`), `site_id`  
            **Emission path:** `telemetry.IncSiteRegistration`  
            **Example:** `newt_site_registrations_total{result="success",site_id="abc"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_site_online" type="ObservableGauge">
          0/1 heartbeat for the active site.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `site_id`  
            **Emission path:** `state.TelemetryView` (callback)  
            **Example:** `newt_site_online{site_id="self"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_site_last_heartbeat_seconds" type="ObservableGauge">
          Seconds since last Pangolin heartbeat.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `site_id`  
            **Emission path:** `TouchHeartbeat` (callback)  
            **Example:** `newt_site_last_heartbeat_seconds{site_id="self"} 3.2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_build_info" type="ObservableGauge">
          Constant 1 with build metadata labels.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `version`, `commit`  
            **Emission path:** Build info registration  
            **Example:** `newt_build_info{version="1.2.3",commit="abc123"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_restart_count_total" type="Counter">
          Process boot indicator (increments once per process start).
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** —  
            **Emission path:** `RegisterBuildInfo`  
            **Example:** `newt_restart_count_total 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_cert_rotation_total" type="Counter">
          Certificate rotation events keyed by result.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `result`  
            **Emission path:** `IncCertRotation`  
            **Example:** `newt_cert_rotation_total{result="success"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_config_reloads_total" type="Counter">
          Config reload attempts keyed by result.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `result`  
            **Emission path:** `telemetry.IncConfigReload`  
            **Example:** `newt_config_reloads_total{result="success"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_config_apply_seconds" type="Histogram (s)">
          Duration per config-apply phase keyed by `phase` and `result`.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `phase`, `result`  
            **Emission path:** `telemetry.ObserveConfigApply`  
            **Example:** `newt_config_apply_seconds_bucket{phase="peer",result="success",le="0.1"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Tunnel">
        <ResponseField name="newt_tunnel_sessions" type="ObservableGauge">
          Active sessions per tunnel (or collapsed).
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `site_id`, `tunnel_id`  
            **Emission path:** `RegisterStateView`  
            **Example:** `newt_tunnel_sessions{site_id="self",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_bytes_total" type="Counter (bytes)">
          Traffic per tunnel, direction, and protocol.
          <Expandable title="Details">
            **Unit:** bytes  
            **Labels:** `tunnel_id`, `direction` (`ingress`|`egress`), `protocol` (`tcp`|`udp`)  
            **Emission path:** Proxy manager  
            **Example:** `newt_tunnel_bytes_total{direction="egress",protocol="tcp",tunnel_id="wgpub"} 8192`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_latency_seconds" type="Histogram (s)">
          RTT samples per tunnel/transport.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `tunnel_id`, `transport`  
            **Emission path:** Health checks  
            **Example:** `newt_tunnel_latency_seconds_bucket{transport="wireguard",le="0.05",tunnel_id="wgpub"} 4`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_reconnects_total" type="Counter">
          Reconnect attempts keyed by initiator & reason.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `tunnel_id`, `initiator` (`client`|`server`), `reason`  
            **Emission path:** `telemetry.IncReconnect`  
            **Example:** `newt_tunnel_reconnects_total{initiator="client",reason="timeout",tunnel_id="wgpub"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Connection & Auth">
        <ResponseField name="newt_connection_attempts_total" type="Counter">
          Auth/WebSocket connection attempts keyed by transport & result.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `transport`, `result`  
            **Emission path:** `telemetry.IncConnAttempt`  
            **Example:** `newt_connection_attempts_total{transport="websocket",result="failure"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_connection_errors_total" type="Counter">
          Connection errors keyed by transport and type.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `transport`, `error_type`  
            **Emission path:** `telemetry.IncConnError`  
            **Example:** `newt_connection_errors_total{transport="auth",error_type="auth_failed"} 1`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="WebSocket">
        <ResponseField name="newt_websocket_connect_latency_seconds" type="Histogram (s)">
          Dial latency for Pangolin WebSocket.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `result`, `transport`  
            **Emission path:** `ObserveWSConnectLatency`  
            **Example:** `newt_websocket_connect_latency_seconds_bucket{result="success",transport="websocket",le="0.5"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_disconnects_total" type="Counter">
          WebSocket disconnects keyed by reason.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `reason`, `tunnel_id`  
            **Emission path:** `IncWSDisconnect`  
            **Example:** `newt_websocket_disconnects_total{reason="remote_close",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_keepalive_failures_total" type="Counter">
          Ping/Pong failures observed by keepalive.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `reason` (e.g., `ping_write`, `pong_timeout`)  
            **Emission path:** `telemetry.IncWSKeepaliveFailure(ctx, "ping_write")`  
            **Example:** `newt_websocket_keepalive_failures_total{reason="ping_write"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_session_duration_seconds" type="Histogram (s)">
          Duration of established WS sessions keyed by result.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `result` (`success`|`error`)  
            **Emission path:** `telemetry.ObserveWSSessionDuration(ctx, time.Since(start).Seconds(), "error")`  
            **Example:** `newt_websocket_session_duration_seconds_bucket{result="error",le="60"} 3`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_connected" type="ObservableGauge">
          Current WS connection state (0/1).
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** —  
            **Emission path:** `telemetry.SetWSConnectionState(true|false)`  
            **Example:** `newt_websocket_connected 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_reconnects_total" type="Counter">
          WebSocket reconnect attempts keyed by reason.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `reason`  
            **Emission path:** `telemetry.IncWSReconnect(ctx, "ping_write")`  
            **Example:** `newt_websocket_reconnects_total{reason="ping_write"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_messages_total" type="Counter">
          In/out WS messages keyed by direction & type.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `direction` (`in`|`out`), `msg_type` (`ping`|`pong`|`text`|...)  
            **Emission path:** `IncWSMessage`  
            **Example:** `newt_websocket_messages_total{direction="out",msg_type="ping"} 4`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Proxy">
        <ResponseField name="newt_proxy_active_connections" type="ObservableGauge">
          Active TCP/UDP proxy connections per tunnel/protocol.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `protocol`, `tunnel_id`  
            **Emission path:** Proxy callback  
            **Example:** `newt_proxy_active_connections{protocol="tcp",tunnel_id="wgpub"} 3`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_buffer_bytes" type="ObservableGauge (bytes)">
          Proxy buffer pool size.
          <Expandable title="Details">
            **Unit:** bytes  
            **Labels:** `protocol`, `tunnel_id`  
            **Emission path:** Proxy callback  
            **Example:** `newt_proxy_buffer_bytes{protocol="tcp",tunnel_id="wgpub"} 10240`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_async_backlog_bytes" type="ObservableGauge (bytes)">
          Unflushed async byte backlog.
          <Expandable title="Details">
            **Unit:** bytes  
            **Labels:** `protocol`, `tunnel_id`  
            **Emission path:** Proxy callback  
            **Example:** `newt_proxy_async_backlog_bytes{protocol="udp",tunnel_id="wgpub"} 4096`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_drops_total" type="Counter">
          Proxy write drops keyed by protocol/tunnel.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `protocol`, `tunnel_id`  
            **Emission path:** `IncProxyDrops`  
            **Example:** `newt_proxy_drops_total{protocol="udp",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_accept_total" type="Counter">
          Proxy accept events keyed by result/reason.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `tunnel_id`, `protocol`, `result`, `reason`  
            **Emission path:** `telemetry.IncProxyAccept(ctx, tunnelID, "tcp", "failure", "timeout")`  
            **Example:** `newt_proxy_accept_total{protocol="tcp",result="failure",reason="timeout"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_connections_total" type="Counter">
          Lifecycle events (opened/closed) per connection.
          <Expandable title="Details">
            **Unit:** 1  
            **Labels:** `tunnel_id`, `protocol`, `event` (`opened`|`closed`)  
            **Emission path:** `telemetry.IncProxyConnectionEvent(ctx, tunnelID, "tcp", telemetry.ProxyConnectionOpened)`  
            **Example:** `newt_proxy_connections_total{protocol="tcp",event="opened"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_connection_duration_seconds" type="Histogram (s)">
          Duration of completed proxy connections.
          <Expandable title="Details">
            **Unit:** seconds  
            **Labels:** `tunnel_id`, `protocol`, `result`  
            **Emission path:** `telemetry.ObserveProxyConnectionDuration(ctx, tunnelID, "tcp", "success", seconds)`  
            **Example:** `newt_proxy_connection_duration_seconds_bucket{protocol="tcp",result="success",le="1"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>
    </ResponseField>
  </Tab>

  <Tab title="Prometheus">
    <ResponseField name="newt">
      Prometheus-style series for the same Newt metrics. Names, labels, and examples mirror the OTel tab.

      <Expandable title="Site & Build">
        <ResponseField name="newt_site_registrations_total" type="counter">
          Counts Pangolin registration attempts keyed by result.
          <Expandable title="Details">
            **Labels:** `result`, `site_id` • **Unit:** 1 • **Path:** `telemetry.IncSiteRegistration`  
            **Example:** `newt_site_registrations_total{result="success",site_id="abc"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_site_online" type="gauge">
          0/1 heartbeat for the active site.
          <Expandable title="Details">
            **Labels:** `site_id` • **Unit:** 1 • **Path:** `state.TelemetryView`  
            **Example:** `newt_site_online{site_id="self"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_site_last_heartbeat_seconds" type="gauge">
          Seconds since last Pangolin heartbeat.
          <Expandable title="Details">
            **Labels:** `site_id` • **Unit:** seconds • **Path:** `TouchHeartbeat`  
            **Example:** `newt_site_last_heartbeat_seconds{site_id="self"} 3.2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_build_info" type="gauge">
          Constant 1 with build metadata labels.
          <Expandable title="Details">
            **Labels:** `version`, `commit` • **Unit:** 1 • **Path:** Build info registration  
            **Example:** `newt_build_info{version="1.2.3",commit="abc123"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_restart_count_total" type="counter">
          Process boot indicator (increments once).
          <Expandable title="Details">
            **Labels:** — • **Unit:** 1 • **Path:** `RegisterBuildInfo`  
            **Example:** `newt_restart_count_total 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_cert_rotation_total" type="counter">
          Certificate rotation events keyed by result.
          <Expandable title="Details">
            **Labels:** `result` • **Unit:** 1 • **Path:** `IncCertRotation`  
            **Example:** `newt_cert_rotation_total{result="success"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_config_reloads_total" type="counter">
          Config reload attempts keyed by result.
          <Expandable title="Details">
            **Labels:** `result` • **Unit:** 1 • **Path:** `telemetry.IncConfigReload`  
            **Example:** `newt_config_reloads_total{result="success"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_config_apply_seconds" type="histogram">
          Duration per config-apply phase & result.
          <Expandable title="Details">
            **Labels:** `phase`, `result` • **Unit:** seconds • **Path:** `telemetry.ObserveConfigApply`  
            **Example:** `newt_config_apply_seconds_bucket{phase="peer",result="success",le="0.1"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Tunnel">
        <ResponseField name="newt_tunnel_sessions" type="gauge">
          Active sessions per tunnel (or collapsed).
          <Expandable title="Details">
            **Labels:** `site_id`, `tunnel_id` • **Unit:** 1 • **Path:** `RegisterStateView`  
            **Example:** `newt_tunnel_sessions{site_id="self",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_bytes_total" type="counter">
          Traffic per tunnel/direction/protocol.
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `direction`, `protocol` • **Unit:** bytes • **Path:** Proxy manager  
            **Example:** `newt_tunnel_bytes_total{direction="egress",protocol="tcp",tunnel_id="wgpub"} 8192`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_latency_seconds" type="histogram">
          RTT samples per tunnel/transport.
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `transport` • **Unit:** seconds • **Path:** Health checks  
            **Example:** `newt_tunnel_latency_seconds_bucket{transport="wireguard",le="0.05",tunnel_id="wgpub"} 4`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_tunnel_reconnects_total" type="counter">
          Reconnect attempts by initiator & reason.
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `initiator`, `reason` • **Unit:** 1 • **Path:** `telemetry.IncReconnect`  
            **Example:** `newt_tunnel_reconnects_total{initiator="client",reason="timeout",tunnel_id="wgpub"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Connection & Auth">
        <ResponseField name="newt_connection_attempts_total" type="counter">
          Auth/WebSocket attempts by transport & result.
          <Expandable title="Details">
            **Labels:** `transport`, `result` • **Unit:** 1 • **Path:** `telemetry.IncConnAttempt`  
            **Example:** `newt_connection_attempts_total{transport="websocket",result="failure"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_connection_errors_total" type="counter">
          Connection errors by transport and type.
          <Expandable title="Details">
            **Labels:** `transport`, `error_type` • **Unit:** 1 • **Path:** `telemetry.IncConnError`  
            **Example:** `newt_connection_errors_total{transport="auth",error_type="auth_failed"} 1`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="WebSocket">
        <ResponseField name="newt_websocket_connect_latency_seconds" type="histogram">
          Dial latency for Pangolin WebSocket.
          <Expandable title="Details">
            **Labels:** `result`, `transport` • **Unit:** seconds • **Path:** `ObserveWSConnectLatency`  
            **Example:** `newt_websocket_connect_latency_seconds_bucket{result="success",transport="websocket",le="0.5"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_disconnects_total" type="counter">
          WS disconnects by reason.
          <Expandable title="Details">
            **Labels:** `reason`, `tunnel_id` • **Unit:** 1 • **Path:** `IncWSDisconnect`  
            **Example:** `newt_websocket_disconnects_total{reason="remote_close",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_keepalive_failures_total" type="counter">
          Keepalive Ping/Pong failures.
          <Expandable title="Details">
            **Labels:** `reason` • **Unit:** 1 • **Path:** `telemetry.IncWSKeepaliveFailure(ctx, "ping_write")`  
            **Example:** `newt_websocket_keepalive_failures_total{reason="ping_write"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_session_duration_seconds" type="histogram">
          Duration of established WebSocket sessions by result.
          <Expandable title="Details">
            **Labels:** `result` • **Unit:** seconds • **Path:** `telemetry.ObserveWSSessionDuration(...)`  
            **Example:** `newt_websocket_session_duration_seconds_bucket{result="error",le="60"} 3`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_connected" type="gauge">
          Current WS connection status (0/1).
          <Expandable title="Details">
            **Labels:** — • **Unit:** 1 • **Path:** `telemetry.SetWSConnectionState(true|false)`  
            **Example:** `newt_websocket_connected 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_reconnects_total" type="counter">
          Reconnect attempts by reason.
          <Expandable title="Details">
            **Labels:** `reason` • **Unit:** 1 • **Path:** `telemetry.IncWSReconnect(ctx, "ping_write")`  
            **Example:** `newt_websocket_reconnects_total{reason="ping_write"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_websocket_messages_total" type="counter">
          In/out WS messages by direction & type.
          <Expandable title="Details">
            **Labels:** `direction`, `msg_type` • **Unit:** 1 • **Path:** `IncWSMessage`  
            **Example:** `newt_websocket_messages_total{direction="out",msg_type="ping"} 4`
          </Expandable>
        </ResponseField>
      </Expandable>

      <Expandable title="Proxy">
        <ResponseField name="newt_proxy_active_connections" type="gauge">
          Active TCP/UDP proxy connections per tunnel/protocol.
          <Expandable title="Details">
            **Labels:** `protocol`, `tunnel_id` • **Unit:** 1 • **Path:** Proxy callback  
            **Example:** `newt_proxy_active_connections{protocol="tcp",tunnel_id="wgpub"} 3`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_buffer_bytes" type="gauge">
          Proxy buffer pool size.
          <Expandable title="Details">
            **Labels:** `protocol`, `tunnel_id` • **Unit:** bytes • **Path:** Proxy callback  
            **Example:** `newt_proxy_buffer_bytes{protocol="tcp",tunnel_id="wgpub"} 10240`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_async_backlog_bytes" type="gauge">
          Unflushed async byte backlog.
          <Expandable title="Details">
            **Labels:** `protocol`, `tunnel_id` • **Unit:** bytes • **Path:** Proxy callback  
            **Example:** `newt_proxy_async_backlog_bytes{protocol="udp",tunnel_id="wgpub"} 4096`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_drops_total" type="counter">
          Proxy write drops per protocol/tunnel.
          <Expandable title="Details">
            **Labels:** `protocol`, `tunnel_id` • **Unit:** 1 • **Path:** `IncProxyDrops`  
            **Example:** `newt_proxy_drops_total{protocol="udp",tunnel_id="wgpub"} 2`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_accept_total" type="counter">
          Proxy accept events by result/reason.
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `protocol`, `result`, `reason` • **Unit:** 1 • **Path:** `telemetry.IncProxyAccept(...)`  
            **Example:** `newt_proxy_accept_total{protocol="tcp",result="failure",reason="timeout"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_connections_total" type="counter">
          Connection lifecycle events (opened/closed).
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `protocol`, `event` • **Unit:** 1 • **Path:** `telemetry.IncProxyConnectionEvent(...)`  
            **Example:** `newt_proxy_connections_total{protocol="tcp",event="opened"} 1`
          </Expandable>
        </ResponseField>

        <ResponseField name="newt_proxy_connection_duration_seconds" type="histogram">
          Duration of completed proxy connections.
          <Expandable title="Details">
            **Labels:** `tunnel_id`, `protocol`, `result` • **Unit:** seconds • **Path:** `telemetry.ObserveProxyConnectionDuration(...)`  
            **Example:** `newt_proxy_connection_duration_seconds_bucket{protocol="tcp",result="success",le="1"} 3`
          </Expandable>
        </ResponseField>
      </Expandable>
    </ResponseField>
  </Tab>
</Tabs>

---

## References

* <Link href="https://opentelemetry.io/docs/">OpenTelemetry Documentation</Link>
* <Link href="https://prometheus.io/docs/introduction/overview/">Prometheus Documentation</Link>

<Tip>
Have improvements or a missing metric? Open an issue or PR referencing this page.
</Tip>

