Remove deployment refs on environment destruction

+ specs

app/models/deployment.rb

@@ -7,6 +7,7 @@ class Deployment < ApplicationRecord
   include UpdatedAtFilterable
   include Importable
   include Gitlab::Utils::StrongMemoize
+  include FastDestroyAll
 
   belongs_to :project, required: true
   belongs_to :environment, required: true
@@ -113,6 +114,26 @@ class Deployment < ApplicationRecord
     success.find_by!(iid: iid)
   end
 
+  class << self
+    ##
+    # FastDestroyAll concerns
+    def begin_fast_destroy
+      preload(:project).find_each.map do |deployment|
+        [deployment.project, deployment.ref_path]
+      end
+    end
+
+    ##
+    # FastDestroyAll concerns
+    def finalize_fast_destroy(params)
+      by_project = params.group_by(&:shift)
+
+      by_project.each do |project, ref_paths|
+        project.repository.delete_refs(*ref_paths.flatten)
+      end
+    end
+  end
+
   def commit
     project.commit(sha)
   end
@@ -280,12 +301,12 @@ class Deployment < ApplicationRecord
     errors.add(:ref, _('The branch or tag does not exist'))
   end
 
-  private
-
   def ref_path
     File.join(environment.ref_path, 'deployments', iid.to_s)
   end
 
+  private
+
   def legacy_finished_at
     self.created_at if success? && !read_attribute(:finished_at)
   end

app/models/environment.rb

@@ -3,6 +3,7 @@
 class Environment < ApplicationRecord
   include Gitlab::Utils::StrongMemoize
   include ReactiveCaching
+  include FastDestroyAll::Helpers
 
   self.reactive_cache_refresh_interval = 1.minute
   self.reactive_cache_lifetime = 55.seconds
@@ -10,7 +11,10 @@ class Environment < ApplicationRecord
 
   belongs_to :project, required: true
 
-  has_many :deployments, -> { visible }, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
+  use_fast_destroy :all_deployments
+
+  has_many :all_deployments, class_name: 'Deployment'
+  has_many :deployments, -> { visible }
   has_many :successful_deployments, -> { success }, class_name: 'Deployment'
   has_many :active_deployments, -> { active }, class_name: 'Deployment'
   has_many :prometheus_alerts, inverse_of: :environment

spec/models/deployment_spec.rb

@@ -623,4 +623,26 @@ describe Deployment do
       expect(deploy.errors[:ref]).not_to be_empty
     end
   end
+
+  describe '.fast_destroy_all' do
+    it 'cleans path_refs for destroyed environments' do
+      project = create(:project, :repository)
+      environment = create(:environment, project: project)
+
+      destroyed_deployments = create_list(:deployment, 2, :success, environment: environment, project: project)
+      other_deployments = create_list(:deployment, 2, :success, environment: environment, project: project)
+
+      (destroyed_deployments + other_deployments).each(&:create_ref)
+
+      described_class.where(id: destroyed_deployments.map(&:id)).fast_destroy_all
+
+      destroyed_deployments.each do |deployment|
+        expect(project.commit(deployment.ref_path)).to be_nil
+      end
+
+      other_deployments.each do |deployment|
+        expect(project.commit(deployment.ref_path)).not_to be_nil
+      end
+    end
+  end
 end

spec/models/environment_spec.rb

@@ -1301,4 +1301,13 @@ describe Environment, :use_clean_rails_memory_store_caching do
       end
     end
   end
+
+  describe '#destroy' do
+    it 'remove the deployment refs from gitaly' do
+      deployment = create(:deployment, :success, environment: environment, project: project)
+      deployment.create_ref
+
+      expect { environment.destroy }.to change { project.commit(deployment.ref_path) }.to(nil)
+    end
+  end
 end