From a66ee26a6b487065db66c487027ce4f816bc5599 Mon Sep 17 00:00:00 2001
From: Cody Soyland <cody@soyland.org>
Date: Tue, 14 Apr 2020 16:35:39 -0500
Subject: [PATCH] Reopen log file on SIGHUP

---
 go.mod           |  3 +++
 go.sum           |  2 ++
 server/server.go | 22 +++++++++++++++++-----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/go.mod b/go.mod
index 9d9ecd366..18e398490 100644
--- a/go.mod
+++ b/go.mod
@@ -2,12 +2,15 @@ module github.com/pilosa/pilosa/v2
 
 replace github.com/hashicorp/memberlist => github.com/pilosa/memberlist v0.1.4-0.20190415211605-f6512523c021
 
+replace github.com/client9/reopen => github.com/codysoyland/reopen v1.0.1-0.20200414204206-42cbe848be3b
+
 require (
 	github.com/CAFxX/gcnotifier v0.0.0-20190112062741-224a280d589d
 	github.com/DataDog/datadog-go v0.0.0-20180822151419-281ae9f2d895
 	github.com/StackExchange/wmi v0.0.0-20190523213315-cbe66965904d // indirect
 	github.com/boltdb/bolt v1.3.1
 	github.com/cespare/xxhash v1.1.0
+	github.com/client9/reopen v0.0.0-00010101000000-000000000000
 	github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd // indirect
 	github.com/davecgh/go-spew v1.1.1
 	github.com/go-ole/go-ole v1.2.4 // indirect
diff --git a/go.sum b/go.sum
index 9da5feace..109caa573 100644
--- a/go.sum
+++ b/go.sum
@@ -26,6 +26,8 @@ github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDk
 github.com/cncf/udpa/go v0.0.0-20191209042840-269d4d468f6f/go.mod h1:M8M6+tZqaGXZJjfX53e64911xZQV5JYwmTeXPW+k8Sc=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd h1:qMd81Ts1T2OTKmB4acZcyKaMtRnY5Y44NuXGX2GFJ1w=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd/go.mod h1:sE/e/2PUdi/liOCUjSTXgM1o87ZssimdTWN964YiIeI=
+github.com/codysoyland/reopen v1.0.1-0.20200414204206-42cbe848be3b h1:CP/etmJf4LXC6I1MJQt+I7oh8geIkWllD/NT0T23Y0c=
+github.com/codysoyland/reopen v1.0.1-0.20200414204206-42cbe848be3b/go.mod h1:8fFEqM7bujfAJw/3T2Z/K8FMh+5vEsZ/8eDbNAVGFH8=
 github.com/coreos/etcd v3.3.10+incompatible/go.mod h1:uF7uidLiAD3TWHmW31ZFd/JWoc32PjwdhPthX9715RE=
 github.com/coreos/go-etcd v2.0.0+incompatible/go.mod h1:Jez6KQU2B/sWsbdaef3ED8NzMklzPG4d5KIOhIy30Tk=
 github.com/coreos/go-semver v0.2.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3EedlOD2RNk=
diff --git a/server/server.go b/server/server.go
index a65ba09be..70d30ab2c 100644
--- a/server/server.go
+++ b/server/server.go
@@ -36,6 +36,7 @@ import (
 
 	"golang.org/x/sync/errgroup"
 
+	"github.com/client9/reopen"
 	"github.com/pilosa/pilosa/v2"
 	"github.com/pilosa/pilosa/v2/boltdb"
 	"github.com/pilosa/pilosa/v2/encoding/proto"
@@ -419,15 +420,26 @@ func (m *Command) setupLogger() error {
 	if m.Config.LogPath == "" {
 		m.logOutput = m.Stderr
 	} else {
-		f, err := os.OpenFile(m.Config.LogPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0600)
+		f, err := reopen.NewFileWriter(m.Config.LogPath)
 		if err != nil {
 			return errors.Wrap(err, "opening file")
 		}
+		sighup := make(chan os.Signal, 1)
+		signal.Notify(sighup, syscall.SIGHUP)
+		go func() {
+			for {
+				// duplicate stderr onto log file
+				err = m.dup(int(f.Fd()), int(os.Stderr.Fd()))
+				if err != nil {
+					io.WriteString(f, "syscall dup error: "+err.Error())
+				}
+
+				// reopen log file on SIGHUP
+				<-sighup
+				f.Reopen()
+			}
+		}()
 		m.logOutput = f
-		err = m.dup(int(f.Fd()), int(os.Stderr.Fd()))
-		if err != nil {
-			return errors.Wrap(err, "syscall dup stderr to logfile")
-		}
 	}
 
 	if m.Config.Verbose {