1 files changed, 82 insertions, 0 deletions
diff --git a/lib/gitlab/background_migration/populate_cluster_kubernetes_namespace_table.rb b/lib/gitlab/background_migration/populate_cluster_kubernetes_namespace_table.rb
new file mode 100644
index 00000000000..35bfc381180
--- /dev/null
+++ b/lib/gitlab/background_migration/populate_cluster_kubernetes_namespace_table.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+#
+# rubocop:disable Style/Documentation
+
+module Gitlab
+  module BackgroundMigration
+    class PopulateClusterKubernetesNamespaceTable
+      include Gitlab::Database::MigrationHelpers
+
+      BATCH_SIZE = 1_000
+
+      module Migratable
+        class KubernetesNamespace < ActiveRecord::Base
+          self.table_name = 'clusters_kubernetes_namespaces'
+        end
+
+        class ClusterProject < ActiveRecord::Base
+          include EachBatch
+
+          self.table_name = 'cluster_projects'
+
+          belongs_to :project
+
+          def self.with_no_kubernetes_namespace
+            where.not(id: Migratable::KubernetesNamespace.select(:cluster_project_id))
+          end
+
+          def namespace
+            slug = "#{project.path}-#{project.id}".downcase
+            slug.gsub(/[^-a-z0-9]/, '-').gsub(/^-+/, '')
+          end
+
+          def service_account
+            "#{namespace}-service-account"
+          end
+        end
+
+        class Project < ActiveRecord::Base
+          self.table_name = 'projects'
+        end
+      end
+
+      def perform
+        cluster_projects_with_no_kubernetes_namespace.each_batch(of: BATCH_SIZE) do |cluster_projects_batch, index|
+          sql_values = sql_values_for(cluster_projects_batch)
+
+          insert_into_cluster_kubernetes_namespace(sql_values)
+        end
+      end
+
+      private
+
+      def cluster_projects_with_no_kubernetes_namespace
+        Migratable::ClusterProject.with_no_kubernetes_namespace
+      end
+
+      def sql_values_for(cluster_projects)
+        cluster_projects.map do |cluster_project|
+          values_for_cluster_project(cluster_project)
+        end
+      end
+
+      def values_for_cluster_project(cluster_project)
+        {
+          cluster_project_id: cluster_project.id,
+          cluster_id: cluster_project.cluster_id,
+          project_id: cluster_project.project_id,
+          namespace: cluster_project.namespace,
+          service_account_name: cluster_project.service_account,
+          created_at: 'NOW()',
+          updated_at: 'NOW()'
+        }
+      end
+
+      def insert_into_cluster_kubernetes_namespace(rows)
+        Gitlab::Database.bulk_insert(Migratable::KubernetesNamespace.table_name,
+                                     rows,
+                                     disable_quote: [:created_at, :updated_at])
+      end
+    end
+  end
+end