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package main
import (
"fmt"
"io"
"log"
"net/http"
"strconv"
"time"
"gitlab.com/gitlab-org/labkit/correlation"
"gitlab.com/gitlab-org/labkit/tracing"
tracingcorrelation "gitlab.com/gitlab-org/labkit/tracing/correlation"
)
func main() {
tracing.Initialize(tracing.WithServiceName("router"))
tr := &http.Transport{
MaxIdleConns: 10,
IdleConnTimeout: 30 * time.Second,
DisableCompression: true,
}
client := &http.Client{
Transport: correlation.NewInstrumentedRoundTripper(tracing.NewRoundTripper(tr)),
}
// Listen and propagate traces
http.Handle("/query",
// Add the tracing middleware in
correlation.InjectCorrelationID(
tracing.Handler(
tracingcorrelation.BaggageHandler(
http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
query := r.URL.Query()
ttlString := query.Get("ttl")
var ttl int
var err error
if ttlString == "" {
ttl = 1
} else {
ttl, err = strconv.Atoi(ttlString)
if err != nil {
ttl = 1
}
}
ttl--
if ttl < 0 {
fmt.Fprintf(w, "Hello")
return
}
nextURL := fmt.Sprintf("http://localhost:8080/query?ttl=%d", ttl)
req, err := http.NewRequest(http.MethodGet, nextURL, nil)
if err != nil {
w.WriteHeader(500)
return
}
req = req.WithContext(r.Context())
resp, err := client.Do(req)
if err != nil {
w.WriteHeader(500)
return
}
defer resp.Body.Close()
_, err = io.Copy(w, resp.Body)
if err != nil {
w.WriteHeader(500)
return
}
})),
// Use this route identifier with the tracing middleware
tracing.WithRouteIdentifier("/query"),
),
correlation.WithPropagation()))
log.Fatal(http.ListenAndServe(":8080", nil))
}
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