Metrics Latest
Reference for all Prometheus metrics exposed by the HTTP Add-on
The interceptor and the external scaler expose metrics via OpenTelemetry, with a Prometheus-compatible endpoint enabled by default on each component.
Endpoint configuration
| Setting | Default | Description |
|---|---|---|
| Port | 2223 | Configurable via OTEL_PROM_EXPORTER_PORT. |
| Path | /metrics | Standard Prometheus scrape path. |
| Enabled | true | Configurable via OTEL_PROM_EXPORTER_ENABLED. |
Both components also support OTLP metric export. See Environment Variables for configuration.
Interceptor metrics
Request count
| Prometheus name | interceptor_request_count_total |
| OTel instrument name | interceptor.request.count |
| Type | Counter |
| Description | Total requests processed by the interceptor proxy. |
Labels:
| Label | Description |
|---|---|
code | HTTP response status code (integer). |
cold_start | true when the request waited for backend readiness, including waits that ended before the backend became ready; otherwise false. |
method | HTTP request method. Non-standard methods are normalized to _OTHER (see Method normalization). |
route_name | Name of the matched InterceptorRoute or HTTPScaledObject. |
route_namespace | Namespace of the matched route resource. |
Request concurrency
| Prometheus name | interceptor_request_concurrency |
| OTel instrument name | interceptor.request.concurrency |
| Type | UpDownCounter (gauge) |
| Description | Requests currently in-flight at the interceptor proxy. |
Labels:
| Label | Description |
|---|---|
route_name | Name of the matched InterceptorRoute or HTTPScaledObject. |
route_namespace | Namespace of the matched route resource. |
Request duration
| Prometheus name | interceptor_request_duration_seconds |
| OTel instrument name | interceptor.request.duration |
| Type | Histogram |
| Unit | Seconds |
| Description | Time from request received to response written. |
Bucket boundaries: 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10, 15, 30, 60, 120, 300.
The first boundaries follow the OTel HTTP semantic conventions, and the additional boundaries expose longer cold-start request durations.
Labels:
| Label | Description |
|---|---|
code | HTTP response status code (integer). |
cold_start | true when the request waited for backend readiness, including waits that ended before the backend became ready; otherwise false. |
method | HTTP request method. Non-standard methods are normalized to _OTHER (see Method normalization). |
route_name | Name of the matched InterceptorRoute or HTTPScaledObject. |
route_namespace | Namespace of the matched route resource. |
Cold-start duration
| Prometheus name | interceptor_cold_start_duration_seconds |
| OTel instrument name | interceptor.cold_start.duration |
| Type | Histogram |
| Unit | Seconds |
| Description | Time spent waiting for a cold-start backend to become ready. |
The metric is recorded only when a request waits for backend readiness.
Bucket boundaries: 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5, 7.5, 10, 15, 30, 60, 120, 300.
Labels:
| Label | Description |
|---|---|
outcome | Readiness wait result: ready when backend became ready, timeout when wait ended with another error, or cancelled when request context was cancelled. |
route_name | Name of the matched InterceptorRoute or HTTPScaledObject. |
route_namespace | Namespace of the matched route resource. |
Cold-start rejections
| Prometheus name | interceptor_cold_start_rejections_total |
| OTel instrument name | interceptor.cold_start.rejections |
| Type | Counter |
| Description | Requests rejected because the cold-start pending request limit was reached. |
Labels:
| Label | Description |
|---|---|
route_name | Name of the matched InterceptorRoute or HTTPScaledObject. |
route_namespace | Namespace of the matched route resource. |
Method normalization
The method label accepts the following standard HTTP methods without modification:
CONNECT, DELETE, GET, HEAD, OPTIONS, PATCH, POST, PUT, TRACE
All other method values are replaced with _OTHER to prevent unbounded label cardinality.
Scaler metrics
Pinger fetch duration
| Prometheus name | scaler_pinger_fetch_duration_seconds |
| OTel instrument name | scaler.pinger.fetch.duration |
| Type | Histogram |
| Unit | Seconds |
| Description | Duration of a queue pinger fetch cycle across all interceptor pods. |
Bucket boundaries: 0.005, 0.01, 0.025, 0.05, 0.075, 0.1, 0.25, 0.5, 0.75, 1, 2.5, 5
Pinger fetch errors
| Prometheus name | scaler_pinger_fetch_errors_total |
| OTel instrument name | scaler.pinger.fetch.errors |
| Type | Counter |
| Description | Total failed queue pinger fetch cycles. |
Pinger endpoints
| Prometheus name | scaler_pinger_endpoints |
| OTel instrument name | scaler.pinger.endpoints |
| Type | Gauge |
| Description | Number of interceptor endpoints the scaler is polling. |