Add management_project_id to clusters

This association will be used for a cluster to indicate which project is
used to manage it.

Validate against duplicate scope for same project. If multiple clusters
with the same scope points to the same management_project, it will be
impossible to deterministically select a cluster

app/models/clusters/cluster.rb

@@ -24,6 +24,7 @@ module Clusters
     KUBE_INGRESS_BASE_DOMAIN = 'KUBE_INGRESS_BASE_DOMAIN'
 
     belongs_to :user
+    belongs_to :management_project, class_name: '::Project', optional: true
 
     has_many :cluster_projects, class_name: 'Clusters::Project'
     has_many :projects, through: :cluster_projects, class_name: '::Project'
@@ -63,6 +64,7 @@ module Clusters
     validate :restrict_modification, on: :update
     validate :no_groups, unless: :group_type?
     validate :no_projects, unless: :project_type?
+    validate :unique_management_project_environment_scope
 
     after_save :clear_reactive_cache!
 
@@ -200,6 +202,18 @@ module Clusters
 
     private
 
+    def unique_management_project_environment_scope
+      return unless management_project
+
+      duplicate_management_clusters = management_project.management_clusters
+        .where(environment_scope: environment_scope)
+        .where.not(id: id)
+
+      if duplicate_management_clusters.any?
+        errors.add(:environment_scope, "cannot add duplicated environment scope")
+      end
+    end
+
     def instance_domain
       @instance_domain ||= Gitlab::CurrentSettings.auto_devops_domain
     end

app/models/project.rb

@@ -247,6 +247,7 @@ class Project < ApplicationRecord
   has_one :cluster_project, class_name: 'Clusters::Project'
   has_many :clusters, through: :cluster_project, class_name: 'Clusters::Cluster'
   has_many :kubernetes_namespaces, class_name: 'Clusters::KubernetesNamespace'
+  has_many :management_clusters, class_name: 'Clusters::Cluster', foreign_key: :management_project_id, inverse_of: :management_project
 
   has_many :prometheus_metrics
 

changelogs/unreleased/cluster_management_projects.yml

+---
+title: Adds management project for a cluster
+merge_request: 17866
+author:
+type: changed

db/migrate/20190930063627_add_management_project_id_to_clusters.rb

+# frozen_string_literal: true
+
+class AddManagementProjectIdToClusters < ActiveRecord::Migration[5.2]
+  DOWNTIME = false
+
+  def change
+    add_column :clusters, :management_project_id, :integer
+  end
+end

db/migrate/20191001040549_add_management_project_id_index_fk_to_clusters.rb

+# frozen_string_literal: true
+
+class AddManagementProjectIdIndexFkToClusters < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_foreign_key :clusters, :projects, column: :management_project_id, on_delete: :nullify
+    add_concurrent_index :clusters, :management_project_id, where: 'management_project_id IS NOT NULL'
+  end
+
+  def down
+    remove_concurrent_index :clusters, :management_project_id
+    remove_foreign_key_if_exists :clusters, column: :management_project_id
+  end
+end

db/schema.rb

@@ -991,7 +991,9 @@ ActiveRecord::Schema.define(version: 2019_10_04_134055) do
     t.string "domain"
     t.boolean "managed", default: true, null: false
     t.boolean "namespace_per_environment", default: true, null: false
+    t.integer "management_project_id"
     t.index ["enabled"], name: "index_clusters_on_enabled"
+    t.index ["management_project_id"], name: "index_clusters_on_management_project_id", where: "(management_project_id IS NOT NULL)"
     t.index ["user_id"], name: "index_clusters_on_user_id"
   end
 
@@ -3983,6 +3985,7 @@ ActiveRecord::Schema.define(version: 2019_10_04_134055) do
   add_foreign_key "cluster_projects", "clusters", on_delete: :cascade
   add_foreign_key "cluster_projects", "projects", on_delete: :cascade
   add_foreign_key "cluster_providers_gcp", "clusters", on_delete: :cascade
+  add_foreign_key "clusters", "projects", column: "management_project_id", name: "fk_f05c5e5a42", on_delete: :nullify
   add_foreign_key "clusters", "users", on_delete: :nullify
   add_foreign_key "clusters_applications_cert_managers", "clusters", on_delete: :cascade
   add_foreign_key "clusters_applications_helm", "clusters", on_delete: :cascade

spec/factories/clusters/clusters.rb

@@ -30,6 +30,10 @@ FactoryBot.define do
       end
     end
 
+    trait :management_project do
+      management_project factory: :project
+    end
+
     trait :namespace_per_environment_disabled do
       namespace_per_environment { false }
     end

spec/lib/gitlab/import_export/all_models.yml

@@ -256,6 +256,7 @@ project:
 - cycle_analytics_stages
 - group
 - namespace
+- management_clusters
 - boards
 - last_event
 - services

spec/models/clusters/cluster_spec.rb

@@ -11,6 +11,7 @@ describe Clusters::Cluster, :use_clean_rails_memory_store_caching do
   subject { build(:cluster) }
 
   it { is_expected.to belong_to(:user) }
+  it { is_expected.to belong_to(:management_project).class_name('::Project') }
   it { is_expected.to have_many(:cluster_projects) }
   it { is_expected.to have_many(:projects) }
   it { is_expected.to have_many(:cluster_groups) }
@@ -289,6 +290,20 @@ describe Clusters::Cluster, :use_clean_rails_memory_store_caching do
         it { is_expected.to be_valid }
       end
     end
+
+    describe 'unique scope for management_project' do
+      let(:project) { create(:project) }
+      let!(:cluster_with_management_project) { create(:cluster, management_project: project) }
+
+      context 'duplicate scopes for the same management project' do
+        let(:cluster) { build(:cluster, management_project: project) }
+
+        it 'adds an error on environment_scope' do
+          expect(cluster).not_to be_valid
+          expect(cluster.errors[:environment_scope].first).to eq('cannot add duplicated environment scope')
+        end
+      end
+    end
   end
 
   describe '.ancestor_clusters_for_clusterable' do

spec/models/project_spec.rb

@@ -92,6 +92,7 @@ describe Project do
     it { is_expected.to have_many(:pipeline_schedules) }
     it { is_expected.to have_many(:members_and_requesters) }
     it { is_expected.to have_many(:clusters) }
+    it { is_expected.to have_many(:management_clusters).class_name('Clusters::Cluster') }
     it { is_expected.to have_many(:kubernetes_namespaces) }
     it { is_expected.to have_many(:custom_attributes).class_name('ProjectCustomAttribute') }
     it { is_expected.to have_many(:project_badges).class_name('ProjectBadge') }