From 4713645dd7fc66a3dee9caa1b6c02b52555e683c Mon Sep 17 00:00:00 2001
From: Povilas Versockas <p.versockas@gmail.com>
Date: Fri, 22 Jun 2018 08:53:47 +0300
Subject: [PATCH] Change to list current members and join only new ones

---
 pkg/cluster/cluster.go | 47 ++++++++++++++++++++++++++++++------------
 1 file changed, 34 insertions(+), 13 deletions(-)

diff --git a/pkg/cluster/cluster.go b/pkg/cluster/cluster.go
index 787fb64dc64..a2988763b04 100644
--- a/pkg/cluster/cluster.go
+++ b/pkg/cluster/cluster.go
@@ -29,6 +29,7 @@ type Peer struct {
 
 	cfg             *memberlist.Config
 	knownPeers      []string
+	advertiseAddr   string
 	refreshInterval time.Duration
 
 	data                 *data
@@ -124,7 +125,7 @@ func New(
 		level.Warn(l).Log("err", "provide --cluster.advertise-address as a routable IP address or hostname")
 	}
 
-	resolvedPeers, err := resolvePeers(context.Background(), knownPeers, advertiseAddr, net.Resolver{}, waitIfEmpty)
+	resolvedPeers, err := resolvePeers(context.Background(), knownPeers, advertiseAddr, *net.DefaultResolver, waitIfEmpty)
 	if err != nil {
 		return nil, errors.Wrap(err, "resolve peers")
 	}
@@ -161,14 +162,15 @@ func New(
 	reg.MustRegister(gossipClusterMembers)
 
 	return &Peer{
-		logger:               l,
-		knownPeers:           knownPeers,
-		cfg:                  cfg,
-		refreshInterval:      refreshInterval,
-		gossipMsgsReceived:   gossipMsgsReceived,
-		gossipClusterMembers: gossipClusterMembers,
-		stopc:                make(chan struct{}),
-		data:                 &data{data: map[string]PeerState{}},
+		logger:                   l,
+		knownPeers:               knownPeers,
+		cfg:                      cfg,
+		refreshInterval:          refreshInterval,
+		gossipMsgsReceived:       gossipMsgsReceived,
+		gossipClusterMembers:     gossipClusterMembers,
+		stopc:                    make(chan struct{}),
+		data:                     &data{data: map[string]PeerState{}},
+		advertiseAddr:            advertiseAddr,
 		advertiseStoreAPIAddr:    advertiseStoreAPIAddr,
 		advertiseQueryAPIAddress: advertiseQueryAPIAddress,
 	}, nil
@@ -241,13 +243,32 @@ func (p *Peer) Refresh() error {
 		return nil
 	}
 
-	prev := p.mlist.NumMembers()
-	curr, err := p.mlist.Join(p.knownPeers)
+	resolvedPeers, err := resolvePeers(context.Background(), p.knownPeers, p.advertiseAddr, *net.DefaultResolver, false)
 	if err != nil {
-		return errors.Wrap(err, "could not refresh memberlist cluster")
+		return errors.Wrapf(err, "refresh cluster could not resolve peers: %v", resolvedPeers)
 	}
-	level.Debug(p.logger).Log("msg", "refreshed cluster", "before", prev, "after", curr)
 
+	currMembers := p.mlist.Members()
+	for _, peer := range resolvedPeers {
+		var isPeerFound bool
+
+		for _, mem := range currMembers {
+			if mem.Address() == peer {
+				isPeerFound = true
+				break
+			}
+		}
+
+		if !isPeerFound {
+			curr, err := p.mlist.Join([]string{peer})
+			if err != nil {
+				return errors.Wrapf(err, "refresh cluster could not join peer: %s", peer)
+			}
+			level.Debug(p.logger).Log("msg", "refresh cluster peer joined", "peer", peer, "before", len(currMembers), "after", curr)
+		}
+	}
+
+	level.Debug(p.logger).Log("msg", "refresh cluster done", "peers", strings.Join(p.knownPeers, ","), "resolvedPeers", strings.Join(resolvedPeers, ","))
 	return nil
 }