Observability: Metrics

Overview

Envoy provide robust platform for metrics, Envoy support three different kinds of stats: counter, gauges, histograms.

Envoy enables prometheus format output via the /stats/prometheus admin endpoint.

Envoy support different kinds of sinks, but EG will only support Open Telemetry sink.

Envoy Gateway leverages Gateway API for configuring managed Envoy proxies. Gateway API defines core, extended, and implementation-specific API support levels for implementers such as Envoy Gateway to expose features. Since metrics is not covered by Core or Extended APIs, EG should provide an easy to config metrics per EnvoyProxy.

Goals

  • Support expose metrics in prometheus way(reuse probe port).
  • Support Open Telemetry stats sink.

Non-Goals

  • Support other stats sink.

Use-Cases

  • Enable prometheus metric
  • Push metrics via Open Telemetry Sink
  • TODO: Customize histogram buckets of target metric
  • TODO: Support stats matcher

ProxyMetric API Type

type ProxyMetrics struct {
	// Prometheus defines the configuration for Admin endpoint `/stats/prometheus`.
	Prometheus *PrometheusProvider `json:"prometheus,omitempty"`
	// Sinks defines the metric sinks where metrics are sent to.
	Sinks []MetricSink `json:"sinks,omitempty"`
}

type MetricSinkType string

const (
	MetricSinkTypeOpenTelemetry MetricSinkType = "OpenTelemetry"
)

type MetricSink struct {
	// Type defines the metric sink type.
	// EG currently only supports OpenTelemetry.
	// +kubebuilder:validation:Enum=OpenTelemetry
	// +kubebuilder:default=OpenTelemetry
	Type MetricSinkType `json:"type"`
	// OpenTelemetry defines the configuration for OpenTelemetry sink.
	// It's required if the sink type is OpenTelemetry.
	OpenTelemetry *OpenTelemetrySink `json:"openTelemetry,omitempty"`
}

type OpenTelemetrySink struct {
	// Host define the service hostname.
	Host string `json:"host"`
	// Port defines the port the service is exposed on.
	//
	// +optional
	// +kubebuilder:validation:Minimum=0
	// +kubebuilder:validation:Maximum=65535
	// +kubebuilder:default=4317
	Port int32 `json:"port,omitempty"`

	// TODO: add support for customizing OpenTelemetry sink in https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/stat_sinks/open_telemetry/v3/open_telemetry.proto#envoy-v3-api-msg-extensions-stat-sinks-open-telemetry-v3-sinkconfig
}

type PrometheusProvider struct {
}

Example

  1. The following is an example to enable prometheus metric.
apiVersion: config.gateway.envoyproxy.io/v1alpha1
kind: EnvoyProxy
metadata:
  name: prometheus
  namespace: envoy-gateway-system
spec:
  telemetry:
    metrics:
      prometheus: {}
  1. The following is an example to send metric via Open Telemetry sink.
apiVersion: config.gateway.envoyproxy.io/v1alpha1
kind: EnvoyProxy
metadata:
  name: otel-sink
  namespace: envoy-gateway-system
spec:
  telemetry:
    metrics:
      sinks:
        - type: OpenTelemetry
          openTelemetry:
            host: otel-collector.monitoring.svc.cluster.local
            port: 4317

Last modified December 7, 2023: feat: support docs preview (#2278) (8f003cd)