1 files changed, 8 insertions, 0 deletions
diff --git a/app/models/clusters/cluster.rb b/app/models/clusters/cluster.rb
index d4f5d499b65..0c36bf5cf48 100644
--- a/app/models/clusters/cluster.rb
+++ b/app/models/clusters/cluster.rb
@@ -2,6 +2,7 @@
 
 module Clusters
   class Cluster < ApplicationRecord
+    prepend HasEnvironmentScope
     include Presentable
     include Gitlab::Utils::StrongMemoize
     include FromUnion
@@ -81,6 +82,7 @@ module Clusters
     validate :no_groups, unless: :group_type?
     validate :no_projects, unless: :project_type?
     validate :unique_management_project_environment_scope
+    validate :unique_environment_scope
 
     after_save :clear_reactive_cache!
 
@@ -354,6 +356,12 @@ module Clusters
       end
     end
 
+    def unique_environment_scope
+      if clusterable.present? && clusterable.clusters.where(environment_scope: environment_scope).where.not(id: id).exists?
+        errors.add(:environment_scope, 'cannot add duplicated environment scope')
+      end
+    end
+
     def managed_namespace(environment)
       Clusters::KubernetesNamespaceFinder.new(
         self,