Add WEIGHTED_MAGLEV to localityLbPolicy enum, and update associated d…

…ocstrings. (GoogleCloudPlatform#7444)

* Add WEIGHTED_MAGLEV to localityLbPolicy enum, and update associated docstrings.

* Example for WEIGHTED_MAGLEV uses HTTP health check.

mmv1/products/compute/BackendService.yaml

@@ -769,6 +769,7 @@ properties:
       - :RANDOM
       - :ORIGINAL_DESTINATION
       - :MAGLEV
+      - :WEIGHTED_MAGLEV
     description: |
       The load balancing algorithm used within the scope of the locality.
       The possible values are:
@@ -797,16 +798,32 @@ properties:
                   build times and host selection times. For more information about
                   Maglev, refer to https://ai.google/research/pubs/pub44824
 
+      * `WEIGHTED_MAGLEV`: Per-instance weighted Load Balancing via health check
+                           reported weights. If set, the Backend Service must
+                           configure a non legacy HTTP-based Health Check, and
+                           health check replies are expected to contain
+                           non-standard HTTP response header field
+                           X-Load-Balancing-Endpoint-Weight to specify the
+                           per-instance weights. If set, Load Balancing is weight
+                           based on the per-instance weights reported in the last
+                           processed health check replies, as long as every
+                           instance either reported a valid weight or had
+                           UNAVAILABLE_WEIGHT. Otherwise, Load Balancing remains
+                           equal-weight.
+
 
       This field is applicable to either:
 
       * A regional backend service with the service_protocol set to HTTP, HTTPS, or HTTP2,
         and loadBalancingScheme set to INTERNAL_MANAGED.
       * A global backend service with the load_balancing_scheme set to INTERNAL_SELF_MANAGED.
+      * A regional backend service with loadBalancingScheme set to EXTERNAL (External Network
+        Load Balancing). Only MAGLEV and WEIGHTED_MAGLEV values are possible for External
+        Network Load Balancing. The default is MAGLEV.
 
 
-      If session_affinity is not NONE, and this field is not set to MAGLEV or RING_HASH,
-      session affinity settings will not take effect.
+      If session_affinity is not NONE, and this field is not set to MAGLEV, WEIGHTED_MAGLEV,
+      or RING_HASH, session affinity settings will not take effect.
 
       Only ROUND_ROBIN and RING_HASH are supported when the backend service is referenced
       by a URL map that is bound to target gRPC proxy that has validate_for_proxyless

mmv1/products/compute/RegionBackendService.yaml

@@ -71,6 +71,12 @@ examples:
       region_backend_service_name: "region-service"
       health_check_name: "rbs-health-check"
     min_version: beta
+  - !ruby/object:Provider::Terraform::Examples
+    name: "region_backend_service_external_weighted"
+    primary_resource_id: "default"
+    vars:
+      region_backend_service_name: "region-service"
+      health_check_name: "rbs-health-check"
   - !ruby/object:Provider::Terraform::Examples
     name: "region_backend_service_ilb_ring_hash"
     primary_resource_id: "default"
@@ -781,6 +787,7 @@ properties:
       - :RANDOM
       - :ORIGINAL_DESTINATION
       - :MAGLEV
+      - :WEIGHTED_MAGLEV
     description: |
       The load balancing algorithm used within the scope of the locality.
       The possible values are:
@@ -809,16 +816,32 @@ properties:
                   build times and host selection times. For more information about
                   Maglev, refer to https://ai.google/research/pubs/pub44824
 
+      * `WEIGHTED_MAGLEV`: Per-instance weighted Load Balancing via health check
+                           reported weights. If set, the Backend Service must
+                           configure a non legacy HTTP-based Health Check, and
+                           health check replies are expected to contain
+                           non-standard HTTP response header field
+                           X-Load-Balancing-Endpoint-Weight to specify the
+                           per-instance weights. If set, Load Balancing is weight
+                           based on the per-instance weights reported in the last
+                           processed health check replies, as long as every
+                           instance either reported a valid weight or had
+                           UNAVAILABLE_WEIGHT. Otherwise, Load Balancing remains
+                           equal-weight.
+
 
       This field is applicable to either:
 
       * A regional backend service with the service_protocol set to HTTP, HTTPS, or HTTP2,
         and loadBalancingScheme set to INTERNAL_MANAGED.
       * A global backend service with the load_balancing_scheme set to INTERNAL_SELF_MANAGED.
+      * A regional backend service with loadBalancingScheme set to EXTERNAL (External Network
+        Load Balancing). Only MAGLEV and WEIGHTED_MAGLEV values are possible for External
+        Network Load Balancing. The default is MAGLEV.
 
 
-      If session_affinity is not NONE, and this field is not set to MAGLEV or RING_HASH,
-      session affinity settings will not take effect.
+      If session_affinity is not NONE, and this field is not set to MAGLEV, WEIGHTED_MAGLEV,
+      or RING_HASH, session affinity settings will not take effect.
 
       Only ROUND_ROBIN and RING_HASH are supported when the backend service is referenced
       by a URL map that is bound to target gRPC proxy that has validate_for_proxyless

mmv1/templates/terraform/examples/region_backend_service_external_weighted.tf.erb

@@ -0,0 +1,17 @@
+resource "google_compute_region_backend_service" "<%= ctx[:primary_resource_id] %>" {
+  region                = "us-central1"
+  name                  = "<%= ctx[:vars]['region_backend_service_name'] %>"
+  health_checks         = [google_compute_region_health_check.health_check.id]
+  protocol              = "TCP"
+  load_balancing_scheme = "EXTERNAL"
+  locality_lb_policy    = "WEIGHTED_MAGLEV"
+}
+
+resource "google_compute_region_health_check" "health_check" {
+  name               = "<%= ctx[:vars]['health_check_name'] %>"
+  region             = "us-central1"
+
+  http_health_check {
+    port = 80
+  }
+}