etcdserver: wait for snapshots before closing raft

Fixes #5374

etcdserver/server.go

@@ -542,12 +542,13 @@ func (s *EtcdServer) run() {
 	defer func() {
 		sched.Stop()
 
+		// wait for snapshots before closing raft so wal stays open
+		s.wg.Wait()
+
 		// must stop raft after scheduler-- etcdserver can leak rafthttp pipelines
 		// by adding a peer after raft stops the transport
 		s.r.stop()
 
-		s.wg.Wait()
-
 		// kv, lessor and backend can be nil if running without v3 enabled
 		// or running unit tests.
 		if s.lessor != nil {

integration/cluster_test.go

@@ -232,9 +232,14 @@ func TestIssue2681(t *testing.T) {
 }
 
 // Ensure we can remove a member after a snapshot then add a new one back.
-func TestIssue2746(t *testing.T) {
+func TestIssue2746(t *testing.T) { testIssue2746(t, 5) }
+
+// With 3 nodes TestIssue2476 sometimes had a shutdown with an inflight snapshot.
+func TestIssue2746WithThree(t *testing.T) { testIssue2746(t, 3) }
+
+func testIssue2746(t *testing.T, members int) {
 	defer testutil.AfterTest(t)
-	c := NewCluster(t, 5)
+	c := NewCluster(t, members)
 
 	for _, m := range c.Members {
 		m.SnapCount = 10
@@ -248,7 +253,7 @@ func TestIssue2746(t *testing.T) {
 		clusterMustProgress(t, c.Members)
 	}
 
-	c.RemoveMember(t, uint64(c.Members[4].s.ID()))
+	c.RemoveMember(t, uint64(c.Members[members-1].s.ID()))
 	c.waitLeader(t, c.Members)
 
 	c.AddMember(t)