banyand/observability/meter_prom.go

//go:build prometheus
// +build prometheus

// Licensed to Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Apache Software Foundation (ASF) licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package observability

import (
	"sync"

	grpcprom "github.com/grpc-ecosystem/go-grpc-middleware/providers/prometheus"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promhttp"

	"github.com/apache/skywalking-banyandb/pkg/meter"
	"github.com/apache/skywalking-banyandb/pkg/meter/prom"
	"google.golang.org/grpc"
)

var (
	reg = prometheus.NewRegistry()

	once       = sync.Once{}
	srvMetrics *grpcprom.ServerMetrics
)

func init() {
	reg.MustRegister(prometheus.NewGoCollector())
	reg.MustRegister(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))
	mux.Handle("/metrics", promhttp.HandlerFor(
		reg,
		promhttp.HandlerOpts{},
	))
}

// NewMeterProvider returns a meter.Provider based on the given scope.
func NewMeterProvider(scope meter.Scope) meter.Provider {
	return prom.NewProvider(scope, reg)
}

// MetricsServerInterceptor returns a server interceptor for metrics.
func MetricsServerInterceptor() (grpc.UnaryServerInterceptor, grpc.StreamServerInterceptor) {
	once.Do(func() {
		srvMetrics = grpcprom.NewServerMetrics(
			grpcprom.WithServerHandlingTimeHistogram(
				grpcprom.WithHistogramBuckets([]float64{0.001, 0.01, 0.1, 0.3, 0.6, 1, 3, 6, 9, 20, 30, 60, 90, 120}),
			),
		)
		reg.MustRegister(srvMetrics)
	})
	return srvMetrics.UnaryServerInterceptor(), srvMetrics.StreamServerInterceptor()
}