upstream: added new option `weighted_priority_health` (#27883)

This computes the health of a priority level by using load balancing weight
instead of the count of healthy hosts.

Signed-off-by: Greg Greenway <ggreenway@apple.com>

Mirrored from https://github.com/envoyproxy/envoy @ 842d1b2ae9b7f73a5055f2117df6f7d086b9e40d

envoy/config/endpoint/v3/endpoint.proto

@@ -35,7 +35,7 @@ message ClusterLoadAssignment {
   option (udpa.annotations.versioning).previous_message_type = "envoy.api.v2.ClusterLoadAssignment";
 
   // Load balancing policy settings.
-  // [#next-free-field: 6]
+  // [#next-free-field: 7]
   message Policy {
     option (udpa.annotations.versioning).previous_message_type =
         "envoy.api.v2.ClusterLoadAssignment.Policy";
@@ -99,6 +99,16 @@ message ClusterLoadAssignment {
     // are considered stale and should be marked unhealthy.
     // Defaults to 0 which means endpoints never go stale.
     google.protobuf.Duration endpoint_stale_after = 4 [(validate.rules).duration = {gt {}}];
+
+    // If true, use the :ref:`load balancing weight
+    // <envoy_v3_api_field_config.endpoint.v3.LbEndpoint.load_balancing_weight>` of healthy and unhealthy
+    // hosts to determine the health of the priority level. If false, use the number of healthy and unhealthy hosts
+    // to determine the health of the priority level, or in other words assume each host has a weight of 1 for
+    // this calculation.
+    //
+    // Note: this is not currently implemented for
+    // :ref:`locality weighted load balancing <arch_overview_load_balancing_locality_weighted_lb>`.
+    bool weighted_priority_health = 6;
   }
 
   // Name of the cluster. This will be the :ref:`service_name

envoy/config/endpoint/v3/endpoint_components.proto

@@ -194,9 +194,9 @@ message LocalityLbEndpoints {
   // default to the highest priority (0).
   //
   // Under usual circumstances, Envoy will only select endpoints for the highest
-  // priority (0). In the event all endpoints for a particular priority are
+  // priority (0). In the event that enough endpoints for a particular priority are
   // unavailable/unhealthy, Envoy will fail over to selecting endpoints for the
-  // next highest priority group.
+  // next highest priority group. Read more at :ref:`priority levels <arch_overview_load_balancing_priority_levels>`.
   //
   // Priorities should range from 0 (highest) to N (lowest) without skipping.
   uint32 priority = 5 [(validate.rules).uint32 = {lte: 128}];