Observability: Metrics
2 minute read
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 by default
- Disable 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 {
// Disable the Prometheus endpoint.
Disable bool `json:"disable,omitempty"`
}
Example
- The following is an example to disable prometheus metric.
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: EnvoyProxy
metadata:
name: prometheus
namespace: envoy-gateway-system
spec:
telemetry:
metrics:
prometheus:
disable: true
- The following is an example to send metric via Open Telemetry sink.
apiVersion: 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
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