Creates Clusterss::ApplciationsController update endpoint

- Creates new route
- Creates new controller action
- Creates call stack:
  Clusterss::ApplciationsController calls -->
  Clusters::Applications::UpdateService calls -->
  Clusters::Applications::ScheduleUpdateService calls -->
  ClusterUpdateAppWorker calls -->
  Clusters::Applications::PatchService -->
  ClusterWaitForAppInstallationWorker

DRY req params

Adds gcp_cluster:cluster_update_app queue

Schedule_update_service is uneeded

Extract common logic to a parent class (UpdateService will need it)

Introduce new UpdateService

Fix rescue class namespace

Fix RuboCop offenses

Adds BaseService for create and update services

Remove request_handler code duplication

Fixes update command

Move update_command to ApplicationCore so all apps can use it

Adds tests for Knative update_command

Adds specs for PatchService

Raise error if update receives an unistalled app

Adds update_service spec

Fix RuboCop offense

Use subject in favor of go

Adds update endpoint specs for project namespace

Adds update endpoint specs for group namespace

2 files changed, 200 insertions, 0 deletions

diff --git a/spec/services/clusters/applications/patch_service_spec.rb b/spec/services/clusters/applications/patch_service_spec.rb
new file mode 100644
index 00000000000..d4ee3243b84
--- /dev/null
+++ b/spec/services/clusters/applications/patch_service_spec.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Clusters::Applications::PatchService do
+  describe '#execute' do
+    let(:application) { create(:clusters_applications_knative, :scheduled) }
+    let!(:update_command) { application.update_command }
+    let(:service) { described_class.new(application) }
+    let(:helm_client) { instance_double(Gitlab::Kubernetes::Helm::Api) }
+
+    before do
+      allow(service).to receive(:update_command).and_return(update_command)
+      allow(service).to receive(:helm_api).and_return(helm_client)
+    end
+
+    context 'when there are no errors' do
+      before do
+        expect(helm_client).to receive(:update).with(update_command)
+        allow(ClusterWaitForAppInstallationWorker).to receive(:perform_in).and_return(nil)
+      end
+
+      it 'make the application updating' do
+        expect(application.cluster).not_to be_nil
+        service.execute
+
+        expect(application).to be_updating
+      end
+
+      it 'schedule async installation status check' do
+        expect(ClusterWaitForAppInstallationWorker).to receive(:perform_in).once
+
+        service.execute
+      end
+    end
+
+    context 'when kubernetes cluster communication fails' do
+      let(:error) { Kubeclient::HttpError.new(500, 'system failure', nil) }
+
+      before do
+        expect(helm_client).to receive(:update).with(update_command).and_raise(error)
+      end
+
+      it 'make the application errored' do
+        service.execute
+
+        expect(application).to be_update_errored
+        expect(application.status_reason).to match('Kubernetes error: 500')
+      end
+
+      it 'logs errors' do
+        expect(service.send(:logger)).to receive(:error).with(
+          {
+            exception: 'Kubeclient::HttpError',
+            message: 'system failure',
+            service: 'Clusters::Applications::PatchService',
+            app_id: application.id,
+            project_ids: application.cluster.project_ids,
+            group_ids: [],
+            error_code: 500
+          }
+        )
+
+        expect(Gitlab::Sentry).to receive(:track_acceptable_exception).with(
+          error,
+          extra: {
+            exception: 'Kubeclient::HttpError',
+            message: 'system failure',
+            service: 'Clusters::Applications::PatchService',
+            app_id: application.id,
+            project_ids: application.cluster.project_ids,
+            group_ids: [],
+            error_code: 500
+          }
+        )
+
+        service.execute
+      end
+    end
+
+    context 'a non kubernetes error happens' do
+      let(:application) { create(:clusters_applications_knative, :scheduled) }
+      let(:error) { StandardError.new('something bad happened') }
+
+      before do
+        expect(application).to receive(:make_updating!).once.and_raise(error)
+      end
+
+      it 'make the application errored' do
+        expect(helm_client).not_to receive(:update)
+
+        service.execute
+
+        expect(application).to be_update_errored
+        expect(application.status_reason).to eq("Can't start update process.")
+      end
+
+      it 'logs errors' do
+        expect(service.send(:logger)).to receive(:error).with(
+          {
+            exception: 'StandardError',
+            error_code: nil,
+            message: 'something bad happened',
+            service: 'Clusters::Applications::PatchService',
+            app_id: application.id,
+            project_ids: application.cluster.projects.pluck(:id),
+            group_ids: []
+          }
+        )
+
+        expect(Gitlab::Sentry).to receive(:track_acceptable_exception).with(
+          error,
+          extra: {
+            exception: 'StandardError',
+            error_code: nil,
+            message: 'something bad happened',
+            service: 'Clusters::Applications::PatchService',
+            app_id: application.id,
+            project_ids: application.cluster.projects.pluck(:id),
+            group_ids: []
+          }
+        )
+
+        service.execute
+      end
+    end
+  end
+end
diff --git a/spec/services/clusters/applications/update_service_spec.rb b/spec/services/clusters/applications/update_service_spec.rb
new file mode 100644
index 00000000000..22ad698f77d
--- /dev/null
+++ b/spec/services/clusters/applications/update_service_spec.rb
@@ -0,0 +1,72 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Clusters::Applications::UpdateService do
+  include TestRequestHelpers
+
+  let(:cluster) { create(:cluster, :project, :provided_by_gcp) }
+  let(:user) { create(:user) }
+  let(:params) { { application: 'knative', hostname: 'udpate.example.com' } }
+  let(:service) { described_class.new(cluster, user, params) }
+
+  subject { service.execute(test_request) }
+
+  describe '#execute' do
+    before do
+      allow(ClusterUpdateAppWorker).to receive(:perform_async)
+    end
+
+    context 'application is not installed' do
+      it 'raises Clusters::Applications::BaseService::InvalidApplicationError' do
+        expect(ClusterUpdateAppWorker).not_to receive(:perform_async)
+
+        expect { subject }
+          .to raise_exception { Clusters::Applications::BaseService::InvalidApplicationError }
+          .and not_change { Clusters::Applications::Knative.count }
+          .and not_change { Clusters::Applications::Knative.with_status(:scheduled).count }
+      end
+    end
+
+    context 'application is installed' do
+      context 'application is schedulable' do
+        let!(:application) do
+          create(:clusters_applications_knative, status: 3, cluster: cluster)
+        end
+
+        it 'updates the application data' do
+          expect do
+            subject
+          end.to change { application.reload.hostname }.to(params[:hostname])
+        end
+
+        it 'makes application scheduled!' do
+          subject
+
+          expect(application.reload).to be_scheduled
+        end
+
+        it 'schedules ClusterUpdateAppWorker' do
+          expect(ClusterUpdateAppWorker).to receive(:perform_async)
+
+          subject
+        end
+      end
+
+      context 'application is not schedulable' do
+        let!(:application) do
+          create(:clusters_applications_knative, status: 4, cluster: cluster)
+        end
+
+        it 'raises StateMachines::InvalidTransition' do
+          expect(ClusterUpdateAppWorker).not_to receive(:perform_async)
+
+          expect { subject }
+            .to raise_exception { StateMachines::InvalidTransition }
+            .and not_change { application.reload.hostname }
+            .and not_change { Clusters::Applications::Knative.with_status(:scheduled).count }
+        end
+      end
+    end
+  end
+end