Expose container_registry_zone_redundancy_enabled as separate top-level variable in ADO and GitHub ALZ modules

By default, the container registry zone redundancy follows the agent/runner
container zone support setting. Users can now independently override it by
setting container_registry_zone_redundancy_enabled, enabling scenarios like
AZ support for runners but not the registry.

Co-authored-by: jtracey93 <41163455+jtracey93@users.noreply.github.com>

Author: Copilot

alz/azuredevops/main.tf

@@ -49,7 +49,7 @@ module "azure" {
   virtual_network_subnet_address_prefix_container_instances = var.virtual_network_subnet_address_prefix_container_instances
   virtual_network_subnet_address_prefix_private_endpoints   = var.virtual_network_subnet_address_prefix_private_endpoints
   storage_account_replication_type                          = var.storage_account_replication_type
-  container_registry_zone_redundancy_enabled                = var.agent_container_zone_support
+  container_registry_zone_redundancy_enabled                = coalesce(var.container_registry_zone_redundancy_enabled, var.agent_container_zone_support)
   public_ip_name                                            = local.resource_names.public_ip
   nat_gateway_name                                          = local.resource_names.nat_gateway
   use_self_hosted_agents                                    = var.use_self_hosted_agents

alz/azuredevops/variables.tf

@@ -391,16 +391,27 @@ variable "agent_container_memory_max" {
 
 variable "agent_container_zone_support" {
   description = <<-EOT
-    **(Optional, default: `true`)** Enable availability zone support for Azure DevOps agent container instances and container registry.
+    **(Optional, default: `true`)** Enable availability zone support for Azure DevOps agent container instances.
 
-    When enabled, containers are distributed across availability zones for higher availability and resilience,
-    and the container registry is configured with zone redundancy.
+    When enabled, containers are distributed across availability zones for higher availability and resilience.
     Some regions do not support availability zones, in which case this should be set to false.
   EOT
   type        = bool
   default     = true
 }
 
+variable "container_registry_zone_redundancy_enabled" {
+  description = <<-EOT
+    **(Optional, default: `null`)** Enable zone redundancy for the Azure Container Registry.
+
+    When enabled, the container registry is replicated across availability zones for higher availability.
+    Some regions do not support zone redundancy, in which case this should be set to false.
+    Defaults to the value of `agent_container_zone_support` if not set.
+  EOT
+  type        = bool
+  default     = null
+}
+
 variable "built_in_configuration_file_names" {
   description = <<-EOT
     **(Optional, default: `["config.yaml", "config-hub-and-spoke-vnet.yaml", "config-virtual-wan.yaml"]`)**

alz/github/main.tf

@@ -50,7 +50,7 @@ module "azure" {
   virtual_network_subnet_address_prefix_container_instances = var.virtual_network_subnet_address_prefix_container_instances
   virtual_network_subnet_address_prefix_private_endpoints   = var.virtual_network_subnet_address_prefix_private_endpoints
   storage_account_replication_type                          = var.storage_account_replication_type
-  container_registry_zone_redundancy_enabled                = var.runner_container_zone_support
+  container_registry_zone_redundancy_enabled                = coalesce(var.container_registry_zone_redundancy_enabled, var.runner_container_zone_support)
   public_ip_name                                            = local.resource_names.public_ip
   nat_gateway_name                                          = local.resource_names.nat_gateway
   use_self_hosted_agents                                    = var.use_self_hosted_runners

alz/github/variables.tf

@@ -496,16 +496,27 @@ variable "runner_container_memory_max" {
 
 variable "runner_container_zone_support" {
   description = <<-EOT
-    **(Optional, default: `true`)** Enable availability zone support for GitHub runner container instances and container registry.
+    **(Optional, default: `true`)** Enable availability zone support for GitHub runner container instances.
 
-    When enabled, containers are distributed across availability zones for higher availability and resilience,
-    and the container registry is configured with zone redundancy.
+    When enabled, containers are distributed across availability zones for higher availability and resilience.
     Some regions do not support availability zones, in which case this should be set to false.
   EOT
   type        = bool
   default     = true
 }
 
+variable "container_registry_zone_redundancy_enabled" {
+  description = <<-EOT
+    **(Optional, default: `null`)** Enable zone redundancy for the Azure Container Registry.
+
+    When enabled, the container registry is replicated across availability zones for higher availability.
+    Some regions do not support zone redundancy, in which case this should be set to false.
+    Defaults to the value of `runner_container_zone_support` if not set.
+  EOT
+  type        = bool
+  default     = null
+}
+
 variable "runner_name_environment_variable" {
   description = <<-EOT
     **(Optional, default: `"GH_RUNNER_NAME"`)** The runner name environment variable supplied to the container.