fix(policy): ignore route .status.parents ordering (#13328)

The `eq_time_insensitive_route_parent_statuses` considers ordering when comparing statuses, even though ordering
doesn't matter. This can result in infite update loops.

Add logic to `eq_time_insensitive_route_parent_statuses` to pre-sort statuses before comparison, thus making the result independent of ordering.

A unit test was added to validate the fix.

Fixes #13327
Signed-off-by: Derek Brown <6845676+DerekTBrown@users.noreply.github.com>

Author: DerekTBrown

policy-controller/k8s/status/src/index.rs

@@ -1521,14 +1521,33 @@ pub(crate) fn invalid_backend_kind(message: &str) -> k8s_core_api::Condition {
     }
 }
 
-fn eq_time_insensitive_route_parent_statuses(
+pub(crate) fn eq_time_insensitive_route_parent_statuses(
     left: &[k8s_gateway_api::RouteParentStatus],
     right: &[k8s_gateway_api::RouteParentStatus],
 ) -> bool {
     if left.len() != right.len() {
         return false;
     }
-    left.iter().zip(right.iter()).all(|(l, r)| {
+
+    // Create sorted versions of the input slices
+    let mut left_sorted: Vec<_> = left.to_vec();
+    let mut right_sorted: Vec<_> = right.to_vec();
+
+    left_sorted.sort_by(|a, b| {
+        a.controller_name
+            .cmp(&b.controller_name)
+            .then_with(|| a.parent_ref.name.cmp(&b.parent_ref.name))
+            .then_with(|| a.parent_ref.namespace.cmp(&b.parent_ref.namespace))
+    });
+    right_sorted.sort_by(|a, b| {
+        a.controller_name
+            .cmp(&b.controller_name)
+            .then_with(|| a.parent_ref.name.cmp(&b.parent_ref.name))
+            .then_with(|| a.parent_ref.namespace.cmp(&b.parent_ref.namespace))
+    });
+
+    // Compare each element in sorted order
+    left_sorted.iter().zip(right_sorted.iter()).all(|(l, r)| {
         l.parent_ref == r.parent_ref
             && l.controller_name == r.controller_name
             && eq_time_insensitive_conditions(&l.conditions, &r.conditions)

policy-controller/k8s/status/src/tests/routes.rs

@@ -7,6 +7,7 @@ use chrono::{DateTime, Utc};
 use linkerd_policy_controller_core::POLICY_CONTROLLER_NAME;
 
 mod grpc;
+mod helpers;
 mod http;
 mod tcp;
 mod tls;

policy-controller/k8s/status/src/tests/routes/helpers.rs

@@ -0,0 +1,17 @@
+use super::make_parent_status;
+use crate::index::eq_time_insensitive_route_parent_statuses;
+
+#[test]
+fn test_eq_time_insensitive_route_parent_statuses_order_sensitive() {
+    // Create RouteParentStatus instances using make_parent_status helper
+    let status1 = make_parent_status("ns", "parent1", "Ready", "True", "AllGood");
+    let status2 = make_parent_status("ns", "parent2", "Ready", "True", "AllGood");
+
+    // Create two lists with the same elements in different orders
+    let list1 = vec![status1.clone(), status2.clone()];
+    let list2 = vec![status2, status1];
+
+    // Assert that eq_time_insensitive_route_parent_statuses returns true
+    // indicating that it considers the two lists equal
+    assert!(eq_time_insensitive_route_parent_statuses(&list1, &list2));
+}