Introduce ExcludedNamespace model/table

Add a new model for LimitExclusion
Add the new model under Namespaces::Storage
Add the storage_limit_exclusion/namespace relation
Cover changes with specs
Document the new table

Changelog: added
MR: !108449

db/docs/namespaces_storage_limit_exclusions.yml

+---
+table_name: namespaces_storage_limit_exclusions
+classes:
+  - Namespaces::Storage::LimitExclusion
+feature_categories:
+  - subscription_cost_management
+description: |
+  Stores namespaces that are excluded from the storage limit.
+  Any namespaces that are included in this table will not have storage limitations applied.
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/108449
+milestone: '15.8'
+gitlab_schema: gitlab_main

db/migrate/20230109093043_create_namespaces_storage_limit_exclusions.rb

+# frozen_string_literal: true
+
+class CreateNamespacesStorageLimitExclusions < Gitlab::Database::Migration[2.1]
+  enable_lock_retries!
+
+  def up
+    create_table :namespaces_storage_limit_exclusions do |t|
+      t.references :namespace,
+                   foreign_key: { on_delete: :cascade },
+                   index: true,
+                   null: false
+      t.text :reason, null: false, limit: 255
+      t.timestamps_with_timezone null: false
+    end
+  end
+
+  def down
+    drop_table :namespaces_storage_limit_exclusions
+  end
+end

db/schema_migrations/20230109093043

+98252d08d480287f1014d7b7c46eafdaa53b9582607e87d5169ec7c314b56ccc
\ No newline at end of file

db/structure.sql

@@ -18342,6 +18342,24 @@ CREATE SEQUENCE namespaces_id_seq
 ALTER SEQUENCE namespaces_id_seq OWNED BY namespaces.id;
+CREATE TABLE namespaces_storage_limit_exclusions (
+    id bigint NOT NULL,
+    namespace_id bigint NOT NULL,
+    reason text NOT NULL,
+    created_at timestamp with time zone NOT NULL,
+    updated_at timestamp with time zone NOT NULL,
+    CONSTRAINT check_81640b2ee2 CHECK ((char_length(reason) <= 255))
+);
+
+CREATE SEQUENCE namespaces_storage_limit_exclusions_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+ALTER SEQUENCE namespaces_storage_limit_exclusions_id_seq OWNED BY namespaces_storage_limit_exclusions.id;
+
 CREATE TABLE namespaces_sync_events (
     id bigint NOT NULL,
     namespace_id bigint NOT NULL
@@ -24381,6 +24399,8 @@ ALTER TABLE ONLY namespace_statistics ALTER COLUMN id SET DEFAULT nextval('names
 ALTER TABLE ONLY namespaces ALTER COLUMN id SET DEFAULT nextval('namespaces_id_seq'::regclass);
+ALTER TABLE ONLY namespaces_storage_limit_exclusions ALTER COLUMN id SET DEFAULT nextval('namespaces_storage_limit_exclusions_id_seq'::regclass);
+
 ALTER TABLE ONLY namespaces_sync_events ALTER COLUMN id SET DEFAULT nextval('namespaces_sync_events_id_seq'::regclass);
 ALTER TABLE ONLY note_diff_files ALTER COLUMN id SET DEFAULT nextval('note_diff_files_id_seq'::regclass);
@@ -26504,6 +26524,9 @@ ALTER TABLE ONLY namespace_statistics
 ALTER TABLE ONLY namespaces
     ADD CONSTRAINT namespaces_pkey PRIMARY KEY (id);
+ALTER TABLE ONLY namespaces_storage_limit_exclusions
+    ADD CONSTRAINT namespaces_storage_limit_exclusions_pkey PRIMARY KEY (id);
+
 ALTER TABLE ONLY namespaces_sync_events
     ADD CONSTRAINT namespaces_sync_events_pkey PRIMARY KEY (id);
@@ -30275,6 +30298,8 @@ CREATE INDEX index_namespaces_on_type_and_visibility_and_parent_id ON namespaces
 CREATE INDEX index_namespaces_public_groups_name_id ON namespaces USING btree (name, id) WHERE (((type)::text = 'Group'::text) AND (visibility_level = 20));
+CREATE INDEX index_namespaces_storage_limit_exclusions_on_namespace_id ON namespaces_storage_limit_exclusions USING btree (namespace_id);
+
 CREATE INDEX index_namespaces_sync_events_on_namespace_id ON namespaces_sync_events USING btree (namespace_id);
 CREATE INDEX index_non_requested_project_members_on_source_id_and_type ON members USING btree (source_id, source_type) WHERE ((requested_at IS NULL) AND ((type)::text = 'ProjectMember'::text));
@@ -34255,6 +34280,9 @@ ALTER TABLE ONLY diff_note_positions
 ALTER TABLE ONLY analytics_cycle_analytics_aggregations
     ADD CONSTRAINT fk_rails_13c8374c7a FOREIGN KEY (group_id) REFERENCES namespaces(id) ON DELETE CASCADE;
+ALTER TABLE ONLY namespaces_storage_limit_exclusions
+    ADD CONSTRAINT fk_rails_14e8f7b0e0 FOREIGN KEY (namespace_id) REFERENCES namespaces(id) ON DELETE CASCADE;
+
 ALTER TABLE ONLY users_security_dashboard_projects
     ADD CONSTRAINT fk_rails_150cd5682c FOREIGN KEY (project_id) REFERENCES projects(id) ON DELETE CASCADE;

ee/app/models/ee/namespace.rb

@@ -27,6 +27,7 @@ module Namespace
       has_one :gitlab_subscription
       has_one :elasticsearch_indexed_namespace
       has_one :upcoming_reconciliation, inverse_of: :namespace, class_name: "GitlabSubscriptions::UpcomingReconciliation"
+      has_one :storage_limit_exclusion, class_name: 'Namespaces::Storage::LimitExclusion'
 
       has_many :compliance_management_frameworks, class_name: "ComplianceManagement::Framework"
 

ee/app/models/namespaces/storage/limit_exclusion.rb

+# frozen_string_literal: true
+module Namespaces
+  module Storage
+    class LimitExclusion < ApplicationRecord
+      self.table_name = "namespaces_storage_limit_exclusions"
+
+      belongs_to :namespace, optional: false
+
+      validates :reason, presence: true, length: { maximum: 255 }
+    end
+  end
+end

ee/spec/factories/namespaces/storage/limit_exclusions.rb

+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :storage_limit_excluded_namespace, class: 'Namespaces::Storage::LimitExclusion' do
+    namespace
+    reason { 'Excluded for testing purposes' }
+  end
+end

ee/spec/models/ee/namespace_spec.rb

@@ -18,6 +18,7 @@
   it { is_expected.to have_one(:security_orchestration_policy_configuration).class_name('Security::OrchestrationPolicyConfiguration').with_foreign_key(:namespace_id) }
   it { is_expected.to have_one :upcoming_reconciliation }
   it { is_expected.to have_many(:ci_minutes_additional_packs) }
+  it { is_expected.to have_one(:storage_limit_exclusion) }
 
   it { is_expected.to delegate_method(:trial?).to(:gitlab_subscription) }
   it { is_expected.to delegate_method(:trial_ends_on).to(:gitlab_subscription) }

ee/spec/models/ee/namespaces/storage/limit_exclusion_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Namespaces::Storage::LimitExclusion, feature_category: :subscription_cost_management, type: :model do
+  describe 'associations' do
+    it { is_expected.to belong_to(:namespace).required }
+  end
+
+  describe 'check constraints' do
+    it 'enforces the reason and namespace NOT NULL constraint' do
+      expect do
+        ApplicationRecord.connection
+        .execute('INSERT INTO namespaces_storage_limit_exclusions (reason, namespace_id) VALUES (NULL, NULL)')
+      end.to raise_error(ActiveRecord::NotNullViolation)
+    end
+  end
+
+  describe 'validations' do
+    it { is_expected.to belong_to(:namespace).optional(false) }
+    it { is_expected.to validate_presence_of(:reason) }
+    it { is_expected.to validate_length_of(:reason).is_at_most(255) }
+  end
+
+  describe 'dependent destroy' do
+    let(:namespace) { create(:namespace) }
+    let!(:excluded_namespace) { create(:storage_limit_excluded_namespace, namespace: namespace) }
+
+    it 'destroys the excluded namespace when the namespace is destroyed' do
+      expect { namespace.destroy! }.to change { described_class.count }.by(-1)
+    end
+  end
+end