chore: add logs-in-context example with logrus

v3/integrations/nrlogrus/examples/server-http-logs-in-context/main.go

@@ -0,0 +1,97 @@
+// Copyright 2020 New Relic Corporation. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+// An application that illustrates Distributed Tracing with Logs-in-Context
+// when using http.Server or similar frameworks.
+package main
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"time"
+
+	"github.com/newrelic/go-agent/v3/integrations/logcontext-v2/nrlogrus"
+	newrelic "github.com/newrelic/go-agent/v3/newrelic"
+	"github.com/sirupsen/logrus"
+)
+
+type handler struct {
+	App *newrelic.Application
+}
+
+func (h *handler) ServeHTTP(writer http.ResponseWriter, req *http.Request) {
+	// The call to StartTransaction must include the response writer and the
+	// request.
+	txn := h.App.StartTransaction("server-txn")
+	defer txn.End()
+
+	txnLogger := logrus.WithContext(newrelic.NewContext(context.Background(), txn))
+
+	writer = txn.SetWebResponse(writer)
+	txn.SetWebRequestHTTP(req)
+
+	if req.URL.String() == "/segments" {
+		defer txn.StartSegment("f1").End()
+
+		txnLogger.Infof("/segments just started")
+
+		func() {
+			defer txn.StartSegment("f2").End()
+
+			io.WriteString(writer, "segments!")
+			time.Sleep(10 * time.Millisecond)
+
+			txnLogger.Infof("segment func just about to complete")
+		}()
+		time.Sleep(10 * time.Millisecond)
+	} else {
+		// Transaction.WriteHeader has to be used instead of invoking
+		// WriteHeader on the response writer.
+		writer.WriteHeader(http.StatusNotFound)
+	}
+	txnLogger.Infof("handler completing")
+}
+
+func makeApplication() (*newrelic.Application, error) {
+	app, err := newrelic.NewApplication(
+		newrelic.ConfigAppName("HTTP Server App"),
+		newrelic.ConfigLicense(os.Getenv("NEW_RELIC_LICENSE_KEY")),
+	)
+	if nil != err {
+		return nil, err
+	}
+	nrlogrusFormatter := nrlogrus.NewFormatter(app, &logrus.TextFormatter{})
+	logrus.SetFormatter(nrlogrusFormatter)
+	// Alternatively and if preferred, create a new logger and use that logger
+	// for logging with
+	// log := logrus.New()
+	// log.SetFormatter(nrlogrusFormatter)
+
+	// Wait for the application to connect.
+	if err = app.WaitForConnection(5 * time.Second); nil != err {
+		return nil, err
+	}
+
+	return app, nil
+}
+
+func main() {
+
+	app, err := makeApplication()
+	if nil != err {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	logrus.Infof("Application Starting")
+
+	server := http.Server{
+		Addr:    ":8000",
+		Handler: &handler{App: app},
+	}
+
+	server.ListenAndServe()
+}