nrzerologplugin: Plugin to support logs in context for Zerolog

v3/integrations/logcontext/nrzerologplugin/go.mod

@@ -0,0 +1,10 @@
+module github.com/newrelic/go-agent/v3/integrations/logcontext/nrzerologplugin
+
+go 1.7
+
+require (
+	github.com/justinas/alice v1.2.0 // indirect
+	github.com/newrelic/go-agent/v3 v3.11.0
+	github.com/rs/zerolog v1.21.0
+)
+

v3/integrations/logcontext/nrzerologplugin/nrzerologplugin.go

@@ -0,0 +1,84 @@
+package nrzerologplugin
+
+import (
+	"net/http"
+	"runtime"
+	"strconv"
+	"time"
+
+	"github.com/newrelic/go-agent/v3/integrations/logcontext"
+	"github.com/newrelic/go-agent/v3/internal"
+	"github.com/newrelic/go-agent/v3/newrelic"
+	"github.com/rs/zerolog"
+)
+
+func init() { internal.TrackUsage("integration", "logcontext", "zerolog") }
+
+// Middleware adds the necessary date to enable logs in context
+func Middleware(h http.Handler) http.Handler {
+	fn := func(w http.ResponseWriter, r *http.Request) {
+
+		updateContextFn := func(c zerolog.Context) zerolog.Context {
+			if txn := newrelic.FromContext(r.Context()); nil != txn {
+				data := map[string]interface{}{
+					logcontext.KeyMessage: zerolog.MessageFieldName,
+					logcontext.KeyLevel:   zerolog.LevelFieldName,
+				}
+
+				logcontext.AddLinkingMetadata(data, txn.GetLinkingMetadata())
+
+				c = c.Fields(data)
+			}
+
+			return c
+		}
+
+		zerolog.Ctx(r.Context()).UpdateContext(updateContextFn)
+		h.ServeHTTP(w, r)
+	}
+
+	return http.HandlerFunc(fn)
+}
+
+// Hook Zerolog hook to add information regarding the file to the logs
+func Hook(e *zerolog.Event, level zerolog.Level, msg string) {
+	if e.Enabled() {
+		// We cannot get the timestamp from zerolog, so we use the current one
+		e.Uint64(logcontext.KeyTimestamp, uint64(time.Now().UnixNano())/uint64(1000*1000))
+
+		// 6 is a magic number, that's the number of frames in the stacktrace we need to
+		// go up until we get to the function/method who actually called the logger.
+		// It depends on how many function calls we introduced and how many are
+		// introduced by zerolog.
+		file, line, method := traceinfo(6)
+		e.Str(logcontext.KeyFile, file)
+		e.Str(logcontext.KeyLine, strconv.Itoa(line))
+		e.Str(logcontext.KeyMethod, method)
+		e.Str(logcontext.KeyLevel, level.String())
+	}
+}
+
+// traceinfo returns the file, line number and function name.
+// calldepth is the number of frames to be ignored.
+func traceinfo(calldepth int) (string, int, string) {
+	pc := make([]uintptr, 1)
+	n := runtime.Callers(calldepth, pc)
+	frames := runtime.CallersFrames(pc[:n])
+	f, _ := frames.Next()
+	return f.File, f.Line, f.Function
+}
+
+// trimPath shortens given path leaving at most given number of right hand
+// segments.
+func trimPath(filepath string, segments int) string {
+	var chunks int
+	for i := len(filepath) - 1; i > 0; i-- {
+		if filepath[i] == '/' {
+			chunks++
+			if chunks >= segments {
+				return filepath[i+1:]
+			}
+		}
+	}
+	return filepath
+}

v3/integrations/logcontext/nrzerologplugin/nrzerologplugin_example_test.go

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+package nrzerologplugin_test
+
+import (
+	"net/http"
+	"os"
+
+	"github.com/justinas/alice"
+	"github.com/newrelic/go-agent/v3/integrations/logcontext/nrzerologplugin"
+	"github.com/rs/zerolog"
+)
+
+func ExampleNrZerologPlugin() {
+	logger := zerolog.New(os.Stdout)
+	logger = logger.Hook(zerolog.HookFunc(nrzerologplugin.Hook))
+
+	myHandler := func(w http.ResponseWriter, r *http.Request) {
+		logger := zerolog.Ctx(r.Context())
+		logger.Info().Msg("hello world")
+		w.Write([]byte("hello world"))
+	}
+
+	chain := alice.New(nrzerologplugin.Middleware).Then(http.HandlerFunc(myHandler))
+
+	http.ListenAndServe(":8000", chain)
+}