Deploy to clusters for a project's groups

Look for matching clusters starting from the closest ancestor, then go
up the ancestor tree.

Then use Ruby to get clusters for each group in order. Not that
efficient, considering we will doing up to `NUMBER_OF_ANCESTORS_ALLOWED`
number of queries, but it's a finite number

Explicitly order query by depth

This allows us to control ordering explicitly and also to reverse the
order which is useful to allow us to be consistent with
Clusters::Cluster.on_environment (EE) which does reverse ordering.

Puts querying group clusters behind Feature Flag. Just in case we have
issues with performance, we can easily disable this

1 files changed, 13 insertions, 0 deletions

diff --git a/app/models/concerns/deployment_platform.rb b/app/models/concerns/deployment_platform.rb
index e57a3383544..d785e0d505f 100644
--- a/app/models/concerns/deployment_platform.rb
+++ b/app/models/concerns/deployment_platform.rb
@@ -13,6 +13,7 @@ module DeploymentPlatform
 
   def find_deployment_platform(environment)
     find_cluster_platform_kubernetes(environment: environment) ||
+      find_group_cluster_platform_kubernetes_with_feature_guard(environment: environment) ||
       find_kubernetes_service_integration ||
       build_cluster_and_deployment_platform
   end
@@ -23,6 +24,18 @@ module DeploymentPlatform
       .last&.platform_kubernetes
   end
 
+  def find_group_cluster_platform_kubernetes_with_feature_guard(environment: nil)
+    return unless Feature.enabled?(:deploy_group_clusters, default_enabled: true)
+
+    find_group_cluster_platform_kubernetes(environment: environment)
+  end
+
+  # EE would override this and utilize environment argument
+  def find_group_cluster_platform_kubernetes(environment: nil)
+    Clusters::Cluster.enabled.default_environment.ordered_group_clusters_for_project(id)
+      .last&.platform_kubernetes
+  end
+
   def find_kubernetes_service_integration
     services.deployment.reorder(nil).find_by(active: true)
   end