Added backend preference to global application load balancers (GoogleCloudPlatform#3139)

Author: apichick

modules/net-lb-app-ext/README.md

@@ -1065,7 +1065,7 @@ After provisioning this change, and verifying that the new certificate is provis
 | [name](variables.tf#L108) | Load balancer name. | <code>string</code> | ✓ |  |
 | [project_id](variables.tf#L204) | Project id. | <code>string</code> | ✓ |  |
 | [backend_buckets_config](variables.tf#L17) | Backend buckets configuration. | <code title="map&#40;object&#40;&#123;&#10;  bucket_name             &#61; string&#10;  compression_mode        &#61; optional&#40;string&#41;&#10;  custom_response_headers &#61; optional&#40;list&#40;string&#41;&#41;&#10;  description             &#61; optional&#40;string&#41;&#10;  edge_security_policy    &#61; optional&#40;string&#41;&#10;  enable_cdn              &#61; optional&#40;bool&#41;&#10;  cdn_policy &#61; optional&#40;object&#40;&#123;&#10;    bypass_cache_on_request_headers &#61; optional&#40;list&#40;string&#41;&#41;&#10;    cache_mode                      &#61; optional&#40;string&#41;&#10;    client_ttl                      &#61; optional&#40;number&#41;&#10;    default_ttl                     &#61; optional&#40;number&#41;&#10;    max_ttl                         &#61; optional&#40;number&#41;&#10;    negative_caching                &#61; optional&#40;bool&#41;&#10;    request_coalescing              &#61; optional&#40;bool&#41;&#10;    serve_while_stale               &#61; optional&#40;number&#41;&#10;    signed_url_cache_max_age_sec    &#61; optional&#40;number&#41;&#10;    cache_key_policy &#61; optional&#40;object&#40;&#123;&#10;      include_http_headers   &#61; optional&#40;list&#40;string&#41;&#41;&#10;      query_string_whitelist &#61; optional&#40;list&#40;string&#41;&#41;&#10;    &#125;&#41;&#41;&#10;    negative_caching_policy &#61; optional&#40;object&#40;&#123;&#10;      code &#61; optional&#40;number&#41;&#10;      ttl  &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
-| [backend_service_configs](variables-backend-service.tf#L19) | Backend service level configuration. | <code title="map&#40;object&#40;&#123;&#10;  affinity_cookie_ttl_sec         &#61; optional&#40;number&#41;&#10;  compression_mode                &#61; optional&#40;string&#41;&#10;  connection_draining_timeout_sec &#61; optional&#40;number&#41;&#10;  custom_request_headers          &#61; optional&#40;list&#40;string&#41;&#41;&#10;  custom_response_headers         &#61; optional&#40;list&#40;string&#41;&#41;&#10;  enable_cdn                      &#61; optional&#40;bool&#41;&#10;  health_checks                   &#61; optional&#40;list&#40;string&#41;, &#91;&#34;default&#34;&#93;&#41;&#10;  log_sample_rate                 &#61; optional&#40;number&#41;&#10;  locality_lb_policy              &#61; optional&#40;string&#41;&#10;  port_name                       &#61; optional&#40;string&#41;&#10;  project_id                      &#61; optional&#40;string&#41;&#10;  protocol                        &#61; optional&#40;string&#41;&#10;  security_policy                 &#61; optional&#40;string&#41;&#10;  session_affinity                &#61; optional&#40;string&#41;&#10;  timeout_sec                     &#61; optional&#40;number&#41;&#10;  backends &#61; list&#40;object&#40;&#123;&#10;    backend         &#61; string&#10;    balancing_mode  &#61; optional&#40;string, &#34;UTILIZATION&#34;&#41;&#10;    capacity_scaler &#61; optional&#40;number, 1&#41;&#10;    description     &#61; optional&#40;string, &#34;Terraform managed.&#34;&#41;&#10;    failover        &#61; optional&#40;bool, false&#41;&#10;    max_connections &#61; optional&#40;object&#40;&#123;&#10;      per_endpoint &#61; optional&#40;number&#41;&#10;      per_group    &#61; optional&#40;number&#41;&#10;      per_instance &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    max_rate &#61; optional&#40;object&#40;&#123;&#10;      per_endpoint &#61; optional&#40;number&#41;&#10;      per_group    &#61; optional&#40;number&#41;&#10;      per_instance &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    max_utilization &#61; optional&#40;number&#41;&#10;  &#125;&#41;&#41;&#10;  cdn_policy &#61; optional&#40;object&#40;&#123;&#10;    cache_mode                   &#61; optional&#40;string&#41;&#10;    client_ttl                   &#61; optional&#40;number&#41;&#10;    default_ttl                  &#61; optional&#40;number&#41;&#10;    max_ttl                      &#61; optional&#40;number&#41;&#10;    negative_caching             &#61; optional&#40;bool&#41;&#10;    serve_while_stale            &#61; optional&#40;number&#41;&#10;    signed_url_cache_max_age_sec &#61; optional&#40;number&#41;&#10;    cache_key_policy &#61; optional&#40;object&#40;&#123;&#10;      include_host           &#61; optional&#40;bool&#41;&#10;      include_named_cookies  &#61; optional&#40;list&#40;string&#41;&#41;&#10;      include_protocol       &#61; optional&#40;bool&#41;&#10;      include_query_string   &#61; optional&#40;bool&#41;&#10;      query_string_blacklist &#61; optional&#40;list&#40;string&#41;&#41;&#10;      query_string_whitelist &#61; optional&#40;list&#40;string&#41;&#41;&#10;    &#125;&#41;&#41;&#10;    negative_caching_policy &#61; optional&#40;object&#40;&#123;&#10;      code &#61; optional&#40;number&#41;&#10;      ttl  &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  circuit_breakers &#61; optional&#40;object&#40;&#123;&#10;    max_connections             &#61; optional&#40;number&#41;&#10;    max_pending_requests        &#61; optional&#40;number&#41;&#10;    max_requests                &#61; optional&#40;number&#41;&#10;    max_requests_per_connection &#61; optional&#40;number&#41;&#10;    max_retries                 &#61; optional&#40;number&#41;&#10;    connect_timeout &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  consistent_hash &#61; optional&#40;object&#40;&#123;&#10;    http_header_name  &#61; optional&#40;string&#41;&#10;    minimum_ring_size &#61; optional&#40;number&#41;&#10;    http_cookie &#61; optional&#40;object&#40;&#123;&#10;      name &#61; optional&#40;string&#41;&#10;      path &#61; optional&#40;string&#41;&#10;      ttl &#61; optional&#40;object&#40;&#123;&#10;        seconds &#61; number&#10;        nanos   &#61; optional&#40;number&#41;&#10;      &#125;&#41;&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  iap_config &#61; optional&#40;object&#40;&#123;&#10;    oauth2_client_id            &#61; optional&#40;string&#41;&#10;    oauth2_client_secret        &#61; optional&#40;string&#41;&#10;    oauth2_client_secret_sha256 &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;&#10;  locality_lb_policies &#61; optional&#40;list&#40;object&#40;&#123;&#10;    policy &#61; optional&#40;object&#40;&#123;&#10;      name &#61; string&#10;    &#125;&#41;&#41;&#10;    custom_policy &#61; optional&#40;object&#40;&#123;&#10;      name &#61; string&#10;      data &#61; optional&#40;string&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#41;&#10;  outlier_detection &#61; optional&#40;object&#40;&#123;&#10;    consecutive_errors                    &#61; optional&#40;number&#41;&#10;    consecutive_gateway_failure           &#61; optional&#40;number&#41;&#10;    enforcing_consecutive_errors          &#61; optional&#40;number&#41;&#10;    enforcing_consecutive_gateway_failure &#61; optional&#40;number&#41;&#10;    enforcing_success_rate                &#61; optional&#40;number&#41;&#10;    max_ejection_percent                  &#61; optional&#40;number&#41;&#10;    success_rate_minimum_hosts            &#61; optional&#40;number&#41;&#10;    success_rate_request_volume           &#61; optional&#40;number&#41;&#10;    success_rate_stdev_factor             &#61; optional&#40;number&#41;&#10;    base_ejection_time &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    interval &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  security_settings &#61; optional&#40;object&#40;&#123;&#10;    client_tls_policy &#61; optional&#40;string&#41;&#10;    subject_alt_names &#61; optional&#40;list&#40;string&#41;&#41;&#10;    aws_v4_authentication &#61; optional&#40;object&#40;&#123;&#10;      access_key_id      &#61; optional&#40;string&#41;&#10;      access_key         &#61; optional&#40;string&#41;&#10;      access_key_version &#61; optional&#40;string&#41;&#10;      origin_region      &#61; optional&#40;string&#41;&#10;    &#125;&#41;&#41;&#10;&#125;&#41;&#41; &#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41; &#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
+| [backend_service_configs](variables-backend-service.tf#L19) | Backend service level configuration. | <code title="map&#40;object&#40;&#123;&#10;  affinity_cookie_ttl_sec         &#61; optional&#40;number&#41;&#10;  compression_mode                &#61; optional&#40;string&#41;&#10;  connection_draining_timeout_sec &#61; optional&#40;number&#41;&#10;  custom_request_headers          &#61; optional&#40;list&#40;string&#41;&#41;&#10;  custom_response_headers         &#61; optional&#40;list&#40;string&#41;&#41;&#10;  enable_cdn                      &#61; optional&#40;bool&#41;&#10;  health_checks                   &#61; optional&#40;list&#40;string&#41;, &#91;&#34;default&#34;&#93;&#41;&#10;  log_sample_rate                 &#61; optional&#40;number&#41;&#10;  locality_lb_policy              &#61; optional&#40;string&#41;&#10;  port_name                       &#61; optional&#40;string&#41;&#10;  project_id                      &#61; optional&#40;string&#41;&#10;  protocol                        &#61; optional&#40;string&#41;&#10;  security_policy                 &#61; optional&#40;string&#41;&#10;  session_affinity                &#61; optional&#40;string&#41;&#10;  timeout_sec                     &#61; optional&#40;number&#41;&#10;  backends &#61; list&#40;object&#40;&#123;&#10;    backend         &#61; string&#10;    preference      &#61; optional&#40;string, &#34;DEFAULT&#34;&#41;&#10;    balancing_mode  &#61; optional&#40;string, &#34;UTILIZATION&#34;&#41;&#10;    capacity_scaler &#61; optional&#40;number, 1&#41;&#10;    description     &#61; optional&#40;string, &#34;Terraform managed.&#34;&#41;&#10;    failover        &#61; optional&#40;bool, false&#41;&#10;    max_connections &#61; optional&#40;object&#40;&#123;&#10;      per_endpoint &#61; optional&#40;number&#41;&#10;      per_group    &#61; optional&#40;number&#41;&#10;      per_instance &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    max_rate &#61; optional&#40;object&#40;&#123;&#10;      per_endpoint &#61; optional&#40;number&#41;&#10;      per_group    &#61; optional&#40;number&#41;&#10;      per_instance &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    max_utilization &#61; optional&#40;number&#41;&#10;  &#125;&#41;&#41;&#10;  cdn_policy &#61; optional&#40;object&#40;&#123;&#10;    cache_mode                   &#61; optional&#40;string&#41;&#10;    client_ttl                   &#61; optional&#40;number&#41;&#10;    default_ttl                  &#61; optional&#40;number&#41;&#10;    max_ttl                      &#61; optional&#40;number&#41;&#10;    negative_caching             &#61; optional&#40;bool&#41;&#10;    serve_while_stale            &#61; optional&#40;number&#41;&#10;    signed_url_cache_max_age_sec &#61; optional&#40;number&#41;&#10;    cache_key_policy &#61; optional&#40;object&#40;&#123;&#10;      include_host           &#61; optional&#40;bool&#41;&#10;      include_named_cookies  &#61; optional&#40;list&#40;string&#41;&#41;&#10;      include_protocol       &#61; optional&#40;bool&#41;&#10;      include_query_string   &#61; optional&#40;bool&#41;&#10;      query_string_blacklist &#61; optional&#40;list&#40;string&#41;&#41;&#10;      query_string_whitelist &#61; optional&#40;list&#40;string&#41;&#41;&#10;    &#125;&#41;&#41;&#10;    negative_caching_policy &#61; optional&#40;object&#40;&#123;&#10;      code &#61; optional&#40;number&#41;&#10;      ttl  &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  circuit_breakers &#61; optional&#40;object&#40;&#123;&#10;    max_connections             &#61; optional&#40;number&#41;&#10;    max_pending_requests        &#61; optional&#40;number&#41;&#10;    max_requests                &#61; optional&#40;number&#41;&#10;    max_requests_per_connection &#61; optional&#40;number&#41;&#10;    max_retries                 &#61; optional&#40;number&#41;&#10;    connect_timeout &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  consistent_hash &#61; optional&#40;object&#40;&#123;&#10;    http_header_name  &#61; optional&#40;string&#41;&#10;    minimum_ring_size &#61; optional&#40;number&#41;&#10;    http_cookie &#61; optional&#40;object&#40;&#123;&#10;      name &#61; optional&#40;string&#41;&#10;      path &#61; optional&#40;string&#41;&#10;      ttl &#61; optional&#40;object&#40;&#123;&#10;        seconds &#61; number&#10;        nanos   &#61; optional&#40;number&#41;&#10;      &#125;&#41;&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  iap_config &#61; optional&#40;object&#40;&#123;&#10;    oauth2_client_id            &#61; optional&#40;string&#41;&#10;    oauth2_client_secret        &#61; optional&#40;string&#41;&#10;    oauth2_client_secret_sha256 &#61; optional&#40;string&#41;&#10;  &#125;&#41;&#41;&#10;  locality_lb_policies &#61; optional&#40;list&#40;object&#40;&#123;&#10;    policy &#61; optional&#40;object&#40;&#123;&#10;      name &#61; string&#10;    &#125;&#41;&#41;&#10;    custom_policy &#61; optional&#40;object&#40;&#123;&#10;      name &#61; string&#10;      data &#61; optional&#40;string&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#41;&#10;  outlier_detection &#61; optional&#40;object&#40;&#123;&#10;    consecutive_errors                    &#61; optional&#40;number&#41;&#10;    consecutive_gateway_failure           &#61; optional&#40;number&#41;&#10;    enforcing_consecutive_errors          &#61; optional&#40;number&#41;&#10;    enforcing_consecutive_gateway_failure &#61; optional&#40;number&#41;&#10;    enforcing_success_rate                &#61; optional&#40;number&#41;&#10;    max_ejection_percent                  &#61; optional&#40;number&#41;&#10;    success_rate_minimum_hosts            &#61; optional&#40;number&#41;&#10;    success_rate_request_volume           &#61; optional&#40;number&#41;&#10;    success_rate_stdev_factor             &#61; optional&#40;number&#41;&#10;    base_ejection_time &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;    interval &#61; optional&#40;object&#40;&#123;&#10;      seconds &#61; number&#10;      nanos   &#61; optional&#40;number&#41;&#10;    &#125;&#41;&#41;&#10;  &#125;&#41;&#41;&#10;  security_settings &#61; optional&#40;object&#40;&#123;&#10;    client_tls_policy &#61; optional&#40;string&#41;&#10;    subject_alt_names &#61; optional&#40;list&#40;string&#41;&#41;&#10;    aws_v4_authentication &#61; optional&#40;object&#40;&#123;&#10;      access_key_id      &#61; optional&#40;string&#41;&#10;      access_key         &#61; optional&#40;string&#41;&#10;      access_key_version &#61; optional&#40;string&#41;&#10;      origin_region      &#61; optional&#40;string&#41;&#10;    &#125;&#41;&#41;&#10;&#125;&#41;&#41; &#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41; &#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |
 | [description](variables.tf#L50) | Optional description used for resources. | <code>string</code> |  | <code>&#34;Terraform managed.&#34;</code> |
 | [forwarding_rules_config](variables.tf#L56) | The optional forwarding rules configuration. | <code title="map&#40;object&#40;&#123;&#10;  address     &#61; optional&#40;string&#41;&#10;  description &#61; optional&#40;string&#41;&#10;  ipv6        &#61; optional&#40;bool, false&#41;&#10;  name        &#61; optional&#40;string&#41;&#10;  ports       &#61; optional&#40;list&#40;number&#41;, null&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code title="&#123;&#10;  &#34;&#34; &#61; &#123;&#125;&#10;&#125;">&#123;&#8230;&#125;</code> |
 | [group_configs](variables.tf#L77) | Optional unmanaged groups to create. Can be referenced in backends via key or outputs. | <code title="map&#40;object&#40;&#123;&#10;  zone        &#61; string&#10;  instances   &#61; optional&#40;list&#40;string&#41;&#41;&#10;  named_ports &#61; optional&#40;map&#40;number&#41;, &#123;&#125;&#41;&#10;  project_id  &#61; optional&#40;string&#41;&#10;&#125;&#41;&#41;">map&#40;object&#40;&#123;&#8230;&#125;&#41;&#41;</code> |  | <code>&#123;&#125;</code> |

modules/net-lb-app-ext/backend-service.tf

@@ -78,6 +78,7 @@ resource "google_compute_backend_service" "default" {
     for_each = { for b in coalesce(each.value.backends, []) : b.backend => b }
     content {
       group           = lookup(local.group_ids, backend.key, backend.key)
+      preference      = backend.value.preference
       balancing_mode  = backend.value.balancing_mode # UTILIZATION, RATE
       capacity_scaler = backend.value.capacity_scaler
       description     = backend.value.description

modules/net-lb-app-ext/variables-backend-service.tf

@@ -37,6 +37,7 @@ variable "backend_service_configs" {
     backends = list(object({
       # group renamed to backend
       backend         = string
+      preference      = optional(string, "DEFAULT")
       balancing_mode  = optional(string, "UTILIZATION")
       capacity_scaler = optional(number, 1)
       description     = optional(string, "Terraform managed.")
@@ -163,6 +164,15 @@ variable "backend_service_configs" {
     ]))
     error_message = "When specified, balancing mode needs to be 'RATE' or 'UTILIZATION'."
   }
+  validation {
+    condition = alltrue(flatten([
+      for backend_service in values(var.backend_service_configs) : [
+        for backend in backend_service.backends : contains(
+          ["DEFAULT", "PREFERRED"], coalesce(backend.preference, "DEFAULT")
+      )]
+    ]))
+    error_message = "When specified, balancing mode needs to be 'DEFAULT' or 'PREFERRED'."
+  }
   validation {
     condition = alltrue([
       for backend_service in values(var.backend_service_configs) :