From 4aabbe529c63fbaaca9c28f74cd4a17cbd1184fb Mon Sep 17 00:00:00 2001
From: "R.B. Boyer" <4903+rboyer@users.noreply.github.com>
Date: Mon, 13 Dec 2021 14:34:49 -0600
Subject: [PATCH] proxycfg: use external addresses in tproxy when crossing
 partition boundaries (#11823)

---
 agent/proxycfg/upstreams.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/agent/proxycfg/upstreams.go b/agent/proxycfg/upstreams.go
index 74015c118d..e5bcc098ec 100644
--- a/agent/proxycfg/upstreams.go
+++ b/agent/proxycfg/upstreams.go
@@ -108,8 +108,10 @@ func (s *handlerUpstreams) handleUpdateUpstreams(ctx context.Context, u cache.Up
 					}
 				}
 
-				// TODO(partitions) Update to account for upstream in remote partition once tproxy supports it
-				addr, _ := node.BestAddress(false)
+				// Make sure to use an external address when crossing partitions.
+				isRemote := !structs.EqualPartitions(svc.PartitionOrDefault(), s.proxyID.PartitionOrDefault())
+				addr, _ := node.BestAddress(isRemote)
+
 				upstreamsSnapshot.PassthroughUpstreams[svc.String()].Addrs[addr] = struct{}{}
 			}
 		}