Cancel builds before uninstalling with Helm and remove runner

- Use the make_uninstalling transition to cancel builds related to
the Clusters::Applications::Runner. If we uninstall with Helm before
doing this, the pod that is running the build might get stuck and never
be done.

- Remove associated Ci::Runner after Clusters::Applications::Runner is
destroyed.

4 files changed, 45 insertions, 7 deletions

diff --git a/app/models/clusters/applications/runner.rb b/app/models/clusters/applications/runner.rb
index 599a100471c..4bdd4867885 100644
--- a/app/models/clusters/applications/runner.rb
+++ b/app/models/clusters/applications/runner.rb
@@ -12,13 +12,11 @@ module Clusters
       include ::Clusters::Concerns::ApplicationVersion
       include ::Clusters::Concerns::ApplicationData
 
-      belongs_to :runner, class_name: 'Ci::Runner', foreign_key: :runner_id
+      belongs_to :runner, class_name: 'Ci::Runner', foreign_key: :runner_id, dependent: :destroy # rubocop:disable Cop/ActiveRecordDependent
       delegate :project, :group, to: :cluster
 
       default_value_for :version, VERSION
 
-      after_destroy :destroy_ci_runner
-
       def chart
         "#{name}/gitlab-runner"
       end
@@ -42,12 +40,12 @@ module Clusters
         )
       end
 
-      private
-
-      def destroy_ci_runner
-        runner.destroy
+      def prepare_uninstall
+        runner.builds.each(&:cancel)
       end
 
+      private
+
       def ensure_runner
         runner || create_and_assign_runner
       end
diff --git a/app/models/clusters/concerns/application_core.rb b/app/models/clusters/concerns/application_core.rb
index 4514498b84b..bc58755c970 100644
--- a/app/models/clusters/concerns/application_core.rb
+++ b/app/models/clusters/concerns/application_core.rb
@@ -46,6 +46,11 @@ module Clusters
             command.version = version
           end
         end
+
+        def prepare_uninstall
+          # Override if your application needs any action before
+          # being uninstalled by Helm
+        end
       end
     end
   end
diff --git a/app/models/clusters/concerns/application_status.rb b/app/models/clusters/concerns/application_status.rb
index f842e6aaf81..e83a7967c40 100644
--- a/app/models/clusters/concerns/application_status.rb
+++ b/app/models/clusters/concerns/application_status.rb
@@ -83,6 +83,10 @@ module Clusters
             # therefore we need to reflect that in the database.
             application.cluster.application_helm.update!(version: Gitlab::Kubernetes::Helm::HELM_VERSION)
           end
+
+          after_transition any => [:uninstalling] do |application, _|
+            application.prepare_uninstall
+          end
         end
       end
 
diff --git a/spec/models/clusters/applications/runner_spec.rb b/spec/models/clusters/applications/runner_spec.rb
index b99f2e13675..0a32c2acd6c 100644
--- a/spec/models/clusters/applications/runner_spec.rb
+++ b/spec/models/clusters/applications/runner_spec.rb
@@ -156,4 +156,35 @@ describe Clusters::Applications::Runner do
       end
     end
   end
+
+  describe '#make_installing!' do
+    subject { create(:clusters_applications_runner, :scheduled, runner: ci_runner) }
+
+    let(:other_runner) { create(:ci_runner) }
+    let(:build) { create(:ci_build, :running, runner: subject.runner) }
+    let(:other_runner_build) { create(:ci_build, :running, runner: other_runner, project: build.project) }
+
+    before do
+      expect(build.runner).not_to eq(other_runner_build.runner)
+      expect(build.project).to eq(other_runner_build.project)
+
+      subject.make_uninstalling!
+    end
+
+    it 'cancels builds of associated runner' do
+      expect(build.reload).to be_canceled
+    end
+
+    it 'does not cancel other runner builds' do
+      expect(other_runner_build.reload).not_to be_canceled
+    end
+  end
+
+  describe '#destroy!' do
+    it 'destroys its runner' do
+      application_runner = create(:clusters_applications_runner, :scheduled, runner: ci_runner)
+
+      expect { application_runner.destroy! }.to change { Ci::Runner.count }.by(-1)
+    end
+  end
 end