From a31b459f337dd3de883e6c10908c2acd71aae3bb Mon Sep 17 00:00:00 2001
From: Ian Letourneau <ian@noma.to>
Date: Wed, 3 Sep 2025 21:55:23 -0400
Subject: [PATCH] fix: de-duplicate backend servers list mapped from topology

---
 harmony/src/infra/opnsense/load_balancer.rs   |  3 +-
 .../modules/okd/bootstrap_load_balancer.rs    |  3 ++
 opnsense-config/src/modules/load_balancer.rs  | 31 ++++++++++---------
 3 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/harmony/src/infra/opnsense/load_balancer.rs b/harmony/src/infra/opnsense/load_balancer.rs
index 3d981ad..9d8154a 100644
--- a/harmony/src/infra/opnsense/load_balancer.rs
+++ b/harmony/src/infra/opnsense/load_balancer.rs
@@ -108,8 +108,7 @@ pub(crate) fn haproxy_xml_config_to_harmony_loadbalancer(
                 }
                 None => {
                     warn!(
-                        "HAProxy config could not find a matching backend for frontend {:?}",
-                        frontend
+                        "HAProxy config could not find a matching backend for frontend {frontend:?}"
                     );
                 }
             }
diff --git a/harmony/src/modules/okd/bootstrap_load_balancer.rs b/harmony/src/modules/okd/bootstrap_load_balancer.rs
index d6cd2f3..63725f0 100644
--- a/harmony/src/modules/okd/bootstrap_load_balancer.rs
+++ b/harmony/src/modules/okd/bootstrap_load_balancer.rs
@@ -54,6 +54,7 @@ impl OKDBootstrapLoadBalancerScore {
             },
         }
     }
+
     fn topology_to_backend_server(topology: &HAClusterTopology, port: u16) -> Vec<BackendServer> {
         let mut backend: Vec<_> = topology
             .control_plane
@@ -67,6 +68,8 @@ impl OKDBootstrapLoadBalancerScore {
             address: topology.bootstrap_host.ip.to_string(),
             port,
         });
+
+        backend.dedup();
         backend
     }
 }
diff --git a/opnsense-config/src/modules/load_balancer.rs b/opnsense-config/src/modules/load_balancer.rs
index 1a35388..6ef6b9b 100644
--- a/opnsense-config/src/modules/load_balancer.rs
+++ b/opnsense-config/src/modules/load_balancer.rs
@@ -47,9 +47,22 @@ impl<'a> LoadBalancerConfig<'a> {
         healthcheck: Option<HAProxyHealthCheck>,
     ) {
         self.remove_service_by_bind_address(&frontend.bind);
+        self.remove_servers(&servers);
+
         self.add_new_service(frontend, backend, servers, healthcheck);
     }
 
+    // Remove the corresponding real servers based on their name if they already exist.
+    fn remove_servers(&mut self, servers: &[HAProxyServer]) {
+        let server_names: HashSet<_> = servers.iter().map(|s| s.name.clone()).collect();
+        self.with_haproxy(|haproxy| {
+            haproxy
+                .servers
+                .servers
+                .retain(|s| !server_names.contains(&s.name));
+        });
+    }
+
     /// Removes a service and its dependent components based on the frontend's bind address.
     /// This performs a cascading delete of the frontend, backend, servers, and health check.
     fn remove_service_by_bind_address(&mut self, bind_address: &str) {
@@ -63,7 +76,7 @@ impl<'a> LoadBalancerConfig<'a> {
             };
 
             remove_healthcheck(haproxy, &old_backend);
-            remove_servers(haproxy, &old_backend);
+            remove_linked_servers(haproxy, &old_backend);
         });
     }
 
@@ -81,19 +94,7 @@ impl<'a> LoadBalancerConfig<'a> {
                 haproxy.healthchecks.healthchecks.push(check);
             }
 
-            let mut existing_server_names: HashSet<_> = haproxy
-                .servers
-                .servers
-                .iter()
-                .map(|s| s.name.clone())
-                .collect();
-
-            for server in servers {
-                if existing_server_names.insert(server.name.clone()) {
-                    haproxy.servers.servers.push(server);
-                }
-            }
-
+            haproxy.servers.servers.extend(servers);
             haproxy.backends.backends.push(backend);
             haproxy.frontends.frontend.push(frontend);
         });
@@ -162,7 +163,7 @@ fn remove_healthcheck(haproxy: &mut HAProxy, backend: &HAProxyBackend) {
 }
 
 /// Remove the backend's servers. This assumes servers are not shared between services.
-fn remove_servers(haproxy: &mut HAProxy, backend: &HAProxyBackend) {
+fn remove_linked_servers(haproxy: &mut HAProxy, backend: &HAProxyBackend) {
     if let Some(server_uuids_str) = &backend.linked_servers.content {
         let server_uuids_to_remove: HashSet<_> = server_uuids_str.split(',').collect();
         haproxy