forked from jaegertracing/jaeger
/
builder.go
89 lines (79 loc) · 2.98 KB
/
builder.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// Licensed 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 metrics
import (
"errors"
"expvar"
"flag"
"net/http"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promhttp"
"github.com/spf13/viper"
"github.com/uber/jaeger-lib/metrics"
jexpvar "github.com/uber/jaeger-lib/metrics/expvar"
jprom "github.com/uber/jaeger-lib/metrics/prometheus"
)
const (
metricsBackend = "metrics-backend"
metricsHTTPRoute = "metrics-http-route"
defaultMetricsBackend = "prometheus"
defaultMetricsRoute = "/metrics"
)
var errUnknownBackend = errors.New("unknown metrics backend specified")
// Builder provides command line options to configure metrics backend used by Jaeger executables.
type Builder struct {
Backend string
HTTPRoute string // endpoint name to expose metrics, e.g. for scraping
handler http.Handler
}
// AddFlags adds flags for Builder.
func AddFlags(flags *flag.FlagSet) {
flags.String(
metricsBackend,
defaultMetricsBackend,
"Defines which metrics backend to use for metrics reporting: expvar, prometheus, none")
flags.String(
metricsHTTPRoute,
defaultMetricsRoute,
"Defines the route of HTTP endpoint for metrics backends that support scraping")
}
// InitFromViper initializes Builder with properties retrieved from Viper.
func (b *Builder) InitFromViper(v *viper.Viper) *Builder {
b.Backend = v.GetString(metricsBackend)
b.HTTPRoute = v.GetString(metricsHTTPRoute)
return b
}
// CreateMetricsFactory creates a metrics factory based on the configured type of the backend.
// If the metrics backend supports HTTP endpoint for scraping, it is stored in the builder and
// can be later added by RegisterHandler function.
func (b *Builder) CreateMetricsFactory(namespace string) (metrics.Factory, error) {
if b.Backend == "prometheus" {
metricsFactory := jprom.New().Namespace(metrics.NSOptions{Name: namespace, Tags: nil})
b.handler = promhttp.HandlerFor(prometheus.DefaultGatherer, promhttp.HandlerOpts{DisableCompression: true})
return metricsFactory, nil
}
if b.Backend == "expvar" {
metricsFactory := jexpvar.NewFactory(10).Namespace(metrics.NSOptions{Name: namespace, Tags: nil})
b.handler = expvar.Handler()
return metricsFactory, nil
}
if b.Backend == "none" || b.Backend == "" {
return metrics.NullFactory, nil
}
return nil, errUnknownBackend
}
// Handler returns an http.Handler for the metrics endpoint.
func (b *Builder) Handler() http.Handler {
return b.handler
}