From 458eb41be1390ae53987477ee9355dd316e02e24 Mon Sep 17 00:00:00 2001
From: freddygv <gh@freddygv.xyz>
Date: Fri, 19 Mar 2021 19:57:23 -0600
Subject: [PATCH] Prevent synthetic upstreams without addresses from failing
 duplicate ip/port validation

---
 agent/structs/structs.go      |  4 +++-
 agent/structs/structs_test.go | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/agent/structs/structs.go b/agent/structs/structs.go
index 91dfd0b4bc..9c8dee49fb 100644
--- a/agent/structs/structs.go
+++ b/agent/structs/structs.go
@@ -1189,7 +1189,9 @@ func (s *NodeService) Validate() error {
 			}
 			addr = net.JoinHostPort(addr, fmt.Sprintf("%d", u.LocalBindPort))
 
-			if _, ok := bindAddrs[addr]; ok {
+			// Centrally configured upstreams will fail this check if there are multiple because they do not have an address/port.
+			// Only consider non-centrally configured upstreams in this check since those are the ones we create listeners for.
+			if _, ok := bindAddrs[addr]; ok && !u.CentrallyConfigured {
 				result = multierror.Append(result, fmt.Errorf(
 					"upstreams cannot contain duplicates by local bind address and port; %q is specified twice", addr))
 				continue
diff --git a/agent/structs/structs_test.go b/agent/structs/structs_test.go
index f6a6f5dddb..05b75f07ea 100644
--- a/agent/structs/structs_test.go
+++ b/agent/structs/structs_test.go
@@ -768,6 +768,24 @@ func TestStructs_NodeService_ValidateConnectProxy(t *testing.T) {
 			},
 			"upstreams cannot contain duplicates",
 		},
+		{
+			"connect-proxy: Centrally configured upstreams can have duplicate ip/port",
+			func(x *NodeService) {
+				x.Proxy.Upstreams = Upstreams{
+					{
+						DestinationType:     UpstreamDestTypeService,
+						DestinationName:     "foo",
+						CentrallyConfigured: true,
+					},
+					{
+						DestinationType:     UpstreamDestTypeService,
+						DestinationName:     "bar",
+						CentrallyConfigured: true,
+					},
+				}
+			},
+			"",
+		},
 		{
 			"connect-proxy: Upstreams duplicated by ip and port",
 			func(x *NodeService) {