prometheus

type Operator interface {
	// GatherMetrics try to collect metrics available on a best-effort manner.
	GatherMetrics() ([]*dto.MetricFamily, error)

	// MetricsHandler returns an interface to gather metrics via HTTP.
	MetricsHandler() http.Handler

	// InitializeMetrics initializes all metrics, with their appropriate null value,
	// for all gRPC methods registered on a gRPC server. This is useful, to ensure
	// that all metrics exist when collecting and querying. The server interceptors
	// MUST be registered BEFORE performing this operation.
	InitializeMetrics(srv *grpc.Server)

	// Client returns the unary and stream interceptor required to instrument a
	// gRPC client instance. Captured metrics include histograms by default; this
	// allows calculating service latency but is expensive.
	//   https://github.com/grpc-ecosystem/go-grpc-prometheus#histograms
	Client() (grpc.UnaryClientInterceptor, grpc.StreamClientInterceptor)

	// Server returns required gRPC interceptors to instrument a server instance.
	// Captured metrics include histograms by default; this allows calculating service
	// latency but is expensive.
	//   https://github.com/grpc-ecosystem/go-grpc-prometheus#histograms
	//
	// Example Grafana base dashboard:
	//   https://grafana.com/grafana/dashboards/9186
	Server() (grpc.UnaryServerInterceptor, grpc.StreamServerInterceptor)
}