From c3753d4d27d677ed024d451ef2f9def18e20a0f2 Mon Sep 17 00:00:00 2001
From: Colin Sullivan <colin.sullivan@apcera.com>
Date: Tue, 18 Oct 2016 12:50:49 -0600
Subject: [PATCH] Generate syslog tag based on executable/link name

---
 logger/syslog.go      | 21 +++++++++++++++++--
 logger/syslog_test.go | 49 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+), 2 deletions(-)

diff --git a/logger/syslog.go b/logger/syslog.go
index 99e2cffb..7d78b53b 100644
--- a/logger/syslog.go
+++ b/logger/syslog.go
@@ -9,6 +9,8 @@ import (
 	"log"
 	"log/syslog"
 	"net/url"
+	"os"
+	"strings"
 )
 
 // SysLogger provides a system logger facility
@@ -18,9 +20,24 @@ type SysLogger struct {
 	trace  bool
 }
 
+// GetSysLoggerTag generates the tag name for use in syslog statements. If
+// the executable is linked, the name of the link will be used as the tag,
+// otherwise, the name of the executable is used.  "gnatsd" is the default
+// for the NATS server.
+func GetSysLoggerTag() string {
+	procName := os.Args[0]
+	if strings.ContainsRune(procName, os.PathSeparator) {
+		parts := strings.FieldsFunc(procName, func(c rune) bool {
+			return c == os.PathSeparator
+		})
+		procName = parts[len(parts)-1]
+	}
+	return procName
+}
+
 // NewSysLogger creates a new system logger
 func NewSysLogger(debug, trace bool) *SysLogger {
-	w, err := syslog.New(syslog.LOG_DAEMON|syslog.LOG_NOTICE, "gnatsd")
+	w, err := syslog.New(syslog.LOG_DAEMON|syslog.LOG_NOTICE, GetSysLoggerTag())
 	if err != nil {
 		log.Fatalf("error connecting to syslog: %q", err.Error())
 	}
@@ -35,7 +52,7 @@ func NewSysLogger(debug, trace bool) *SysLogger {
 // NewRemoteSysLogger creates a new remote system logger
 func NewRemoteSysLogger(fqn string, debug, trace bool) *SysLogger {
 	network, addr := getNetworkAndAddr(fqn)
-	w, err := syslog.Dial(network, addr, syslog.LOG_DEBUG, "gnatsd")
+	w, err := syslog.Dial(network, addr, syslog.LOG_DEBUG, GetSysLoggerTag())
 	if err != nil {
 		log.Fatalf("error connecting to syslog: %q", err.Error())
 	}
diff --git a/logger/syslog_test.go b/logger/syslog_test.go
index 16452e80..dfe22f1c 100644
--- a/logger/syslog_test.go
+++ b/logger/syslog_test.go
@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"log"
 	"net"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 	"time"
@@ -37,6 +39,53 @@ func TestSysLoggerWithDebugAndTrace(t *testing.T) {
 	}
 }
 
+func testTag(t *testing.T, exePath, expected string) {
+	os.Args[0] = exePath
+	if result := GetSysLoggerTag(); result != expected {
+		t.Fatalf("Expected %s, received %s", expected, result)
+	}
+}
+
+func restoreArg(orig string) {
+	os.Args[0] = orig
+}
+
+func TestSysLoggerTagGen(t *testing.T) {
+	origArg := os.Args[0]
+	defer restoreArg(origArg)
+
+	testTag(t, "gnatsd", "gnatsd")
+	testTag(t, filepath.Join(".", "gnatsd"), "gnatsd")
+	testTag(t, filepath.Join("home", "bin", "gnatsd"), "gnatsd")
+	testTag(t, filepath.Join("..", "..", "gnatsd"), "gnatsd")
+	testTag(t, "gnatsd.service1", "gnatsd.service1")
+	testTag(t, "gnatsd_service1", "gnatsd_service1")
+	testTag(t, "gnatsd-service1", "gnatsd-service1")
+	testTag(t, "gnatsd service1", "gnatsd service1")
+}
+
+func TestSysLoggerTag(t *testing.T) {
+	origArg := os.Args[0]
+	defer restoreArg(origArg)
+
+	os.Args[0] = "ServerLoggerTag"
+
+	done := make(chan string)
+	startServer(done)
+	logger := NewRemoteSysLogger(serverFQN, true, true)
+	logger.Noticef("foo")
+
+	line := <-done
+	data := strings.Split(line, "[")
+	if len(data) != 2 {
+		t.Fatalf("Unexpected syslog line %s\n", line)
+	}
+
+	if !strings.Contains(data[0], os.Args[0]) {
+		t.Fatalf("Expected '%s', received '%s'\n", os.Args[0], data[0])
+	}
+}
+
 func TestRemoteSysLogger(t *testing.T) {
 	done := make(chan string)
 	startServer(done)