From 9f87f9d6e78320c2445a34ab3016b56374e9d2ce Mon Sep 17 00:00:00 2001
From: Simon Pasquier <spasquie@redhat.com>
Date: Thu, 7 Jun 2018 17:57:01 +0200
Subject: [PATCH] cluster: advertise explicitly for empty addresses (#1386)

memberlist doesn't advertise a valid IP address when the bind address is
empty (":8001") or the unspecified IPv6 address ("[::]:8001).

Signed-off-by: Simon Pasquier <spasquie@redhat.com>
---
 cluster/advertise.go |  2 +-
 cluster/cluster.go   | 16 ++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/cluster/advertise.go b/cluster/advertise.go
index 5d7539eb..fb71cf01 100644
--- a/cluster/advertise.go
+++ b/cluster/advertise.go
@@ -38,7 +38,7 @@ func calculateAdvertiseAddress(bindAddr, advertiseAddr string) (net.IP, error) {
 		return ip, nil
 	}
 
-	if bindAddr == "0.0.0.0" {
+	if isAny(bindAddr) {
 		privateIP, err := sockaddr.GetPrivateIP()
 		if err != nil {
 			return nil, errors.Wrap(err, "failed to get private IP")
diff --git a/cluster/cluster.go b/cluster/cluster.go
index d9c8862b..3a2bec4a 100644
--- a/cluster/cluster.go
+++ b/cluster/cluster.go
@@ -122,9 +122,9 @@ func Join(
 	if err != nil {
 		return nil, errors.Wrap(err, "invalid listen address")
 	}
+
 	var advertiseHost string
 	var advertisePort int
-
 	if advertiseAddr != "" {
 		var advertisePortStr string
 		advertiseHost, advertisePortStr, err = net.SplitHostPort(advertiseAddr)
@@ -151,6 +151,11 @@ func Join(
 		level.Warn(l).Log("err", "this node advertises itself on an unroutable address", "addr", addr.String())
 		level.Warn(l).Log("err", "this node will be unreachable in the cluster")
 		level.Warn(l).Log("err", "provide --cluster.advertise-address as a routable IP address or hostname")
+	} else if isAny(bindAddr) && advertiseHost == "" {
+		// memberlist doesn't advertise properly when the bind address is empty or unspecified.
+		level.Info(l).Log("msg", "setting advertise address explicitly", "addr", addr.String(), "port", bindPort)
+		advertiseHost = addr.String()
+		advertisePort = bindPort
 	}
 
 	// TODO(fabxc): generate human-readable but random names?
@@ -184,7 +189,7 @@ func Join(
 	cfg.ProbeInterval = probeInterval
 	cfg.LogOutput = &logWriter{l: l}
 
-	if advertiseAddr != "" {
+	if advertiseHost != "" {
 		cfg.AdvertiseAddr = advertiseHost
 		cfg.AdvertisePort = advertisePort
 	}
@@ -667,6 +672,13 @@ func isUnroutable(addr string) bool {
 	return false
 }
 
+func isAny(addr string) bool {
+	if host, _, err := net.SplitHostPort(addr); err == nil {
+		addr = host
+	}
+	return addr == "" || net.ParseIP(addr).IsUnspecified()
+}
+
 // retry executes f every interval seconds until timeout or no error is returned from f.
 func retry(interval time.Duration, stopc <-chan struct{}, f func() error) error {
 	tick := time.NewTicker(interval)