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// Copyright 2018, OpenCensus Authors
//
// 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 main
import (
"fmt"
"log"
"net/http"
"time"
"go.opencensus.io/zpages"
"go.opencensus.io/examples/exporter"
"go.opencensus.io/plugin/ochttp"
"go.opencensus.io/stats/view"
"go.opencensus.io/trace"
)
const (
metricsLogFile = "/tmp/metrics.log"
tracesLogFile = "/tmp/trace.log"
)
func main() {
// Start z-Pages server.
go func() {
mux := http.NewServeMux()
zpages.Handle(mux, "/debug")
log.Fatal(http.ListenAndServe("127.0.0.1:8081", mux))
}()
// Using log exporter to export metrics but you can choose any supported exporter.
exporter, err := exporter.NewLogExporter(exporter.Options{
ReportingInterval: 10 * time.Second,
MetricsLogFile: metricsLogFile,
TracesLogFile: tracesLogFile,
})
if err != nil {
log.Fatalf("Error creating log exporter: %v", err)
}
exporter.Start()
defer exporter.Stop()
defer exporter.Close()
// Always trace for this demo. In a production application, you should
// configure this to a trace.ProbabilitySampler set at the desired
// probability.
trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
// Report stats at every second.
view.SetReportingPeriod(1 * time.Second)
client := &http.Client{Transport: &ochttp.Transport{}}
http.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
fmt.Fprintf(w, "hello world")
// Provide an example of how spans can be annotated with metadata
_, span := trace.StartSpan(req.Context(), "child")
defer span.End()
span.Annotate([]trace.Attribute{trace.StringAttribute("key", "value")}, "something happened")
span.AddAttributes(trace.StringAttribute("hello", "world"))
time.Sleep(time.Millisecond * 125)
r, _ := http.NewRequest("GET", "https://example.com", nil)
// Propagate the trace header info in the outgoing requests.
r = r.WithContext(req.Context())
resp, err := client.Do(r)
if err != nil {
log.Println(err)
} else {
// TODO: handle response
resp.Body.Close()
}
})
log.Fatal(http.ListenAndServe(":50030", &ochttp.Handler{}))
}
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