From f012a16f05e87318153d83a5291ba39810c0ba83 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emmanuel=20BENO=C3=8ET?=
 <emmanuel.benoit@agrocampus-ouest.fr>
Date: Sat, 13 Feb 2021 23:42:32 +0100
Subject: [PATCH] Logging to a Graylog server

Added the --log-graylog command line argument which sends logs to a
Graylog server using GELF/UDP.
---
 README.md |  2 --
 go.mod    |  1 +
 main.go   | 15 +++++++++++----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 3a05c4a..acc0f80 100644
--- a/README.md
+++ b/README.md
@@ -52,8 +52,6 @@ go build
 To Do
 ------
 
-* Proper logging, work in progress:
-  * Sending logs to... well, Graylog... through CLI switches.
 * Document command line flags.
 * Add TLS options (skip checks / specify CA) for the Graylog API.
 * Read object ownership using `grn_permissions` to preserve privileges on users'
diff --git a/go.mod b/go.mod
index f6a18dd..b305b94 100644
--- a/go.mod
+++ b/go.mod
@@ -3,6 +3,7 @@ module glgroups
 go 1.15
 
 require (
+	github.com/gemnasium/logrus-graylog-hook/v3 v3.0.2
 	github.com/go-ldap/ldap v3.0.3+incompatible
 	github.com/sirupsen/logrus v1.7.0
 	gopkg.in/asn1-ber.v1 v1.0.0-20181015200546-f715ec2f112d // indirect
diff --git a/main.go b/main.go
index 92d4714..e5dda18 100644
--- a/main.go
+++ b/main.go
@@ -5,6 +5,7 @@ import (
 	"io/ioutil"
 	"os"
 
+	lrh_gl "github.com/gemnasium/logrus-graylog-hook/v3"
 	"github.com/sirupsen/logrus"
 	lrh_wr "github.com/sirupsen/logrus/hooks/writer"
 )
@@ -22,6 +23,8 @@ type (
 		logLevel string
 		// A file to write logs into.
 		logFile string
+		// Graylog server to send logs to (using GELF/UDP). Format is <hostname>:<port>.
+		logGraylog string
 	}
 )
 
@@ -34,10 +37,11 @@ var (
 func parseCommandLine() cliFlags {
 	flags := cliFlags{}
 	flag.StringVar(&flags.cfgFile, "c", "graylog-groups.yml", "Configuration file.")
-	flag.StringVar(&flags.instance, "i", "", "Instance identifier.")
-	flag.BoolVar(&flags.quiet, "q", false, "Quiet mode.")
-	flag.StringVar(&flags.logLevel, "L", "", "Log level.")
-	flag.StringVar(&flags.logFile, "log-file", "", "Log file.")
+	flag.StringVar(&flags.instance, "i", "", "Instance identifier")
+	flag.BoolVar(&flags.quiet, "q", false, "Quiet mode")
+	flag.StringVar(&flags.logLevel, "L", "", "Log level")
+	flag.StringVar(&flags.logFile, "log-file", "", "Log file")
+	flag.StringVar(&flags.logGraylog, "log-graylog", "", "Log to Graylog server (format: <host>:<port>)")
 	flag.Parse()
 	return flags
 }
@@ -94,6 +98,9 @@ func configureLogging(flags cliFlags) {
 	if flags.logFile != "" {
 		configureLogFile(flags.logFile)
 	}
+	if flags.logGraylog != "" {
+		log.Logger.AddHook(lrh_gl.NewGraylogHook(flags.logGraylog, nil))
+	}
 	if flags.quiet {
 		log.Logger.SetOutput(ioutil.Discard)
 	}