Add SIGHUP support to reload telegraf config

closes #539

CHANGELOG.md

@@ -9,6 +9,7 @@
 - [#534](https://github.com/influxdata/telegraf/pull/534): NSQ input plugin. Thanks @allingeek!
 - [#494](https://github.com/influxdata/telegraf/pull/494): Graphite output plugin. Thanks @titilambert!
 - AMQP SSL support. Thanks @ekini!
+- [#539](https://github.com/influxdata/telegraf/pull/539): Reload config on SIGHUP. Thanks @titilambert!
 
 ### Bugfixes
 - [#506](https://github.com/influxdb/telegraf/pull/506): Ping input doesn't return response time metric when timeout. Thanks @titilambert!

cmd/telegraf/telegraf.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"os/signal"
 	"strings"
+	"syscall"
 
 	"github.com/influxdb/telegraf"
 	"github.com/influxdb/telegraf/internal/config"
@@ -82,6 +83,10 @@ Examples:
 `
 
 func main() {
+	reload := make(chan bool, 1)
+	reload <- true
+	for <-reload {
+		reload <- false
 		flag.Usage = usageExit
 		flag.Parse()
 
@@ -196,10 +201,18 @@ func main() {
 
 		shutdown := make(chan struct{})
 		signals := make(chan os.Signal)
-	signal.Notify(signals, os.Interrupt)
+		signal.Notify(signals, os.Interrupt, syscall.SIGHUP)
 		go func() {
-		<-signals
+			sig := <-signals
+			if sig == os.Interrupt {
 				close(shutdown)
+			}
+			if sig == syscall.SIGHUP {
+				log.Printf("Reloading Telegraf config\n")
+				<-reload
+				reload <- true
+				close(shutdown)
+			}
 		}()
 
 		log.Printf("Starting Telegraf (version %s)\n", Version)
@@ -219,6 +232,7 @@ func main() {
 		}
 
 		ag.Run(shutdown)
+	}
 }
 
 func usageExit() {