Send notification mails for external alerts

ee/app/presenters/projects/prometheus/alert_presenter.rb

@@ -4,7 +4,7 @@ module Projects
   module Prometheus
     class AlertPresenter < Gitlab::View::Presenter::Delegated
       def email_subject
-        [environment_name, query_title].compact.join(' ')
+        [environment_name, alert_title].compact.join(' ')
       end
 
       def project_full_path
@@ -29,6 +29,10 @@ module Projects
 
       private
 
+      def alert_title
+        query_title || title
+      end
+
       def query_title
         return unless gitlab_alert
 

ee/app/views/notify/prometheus_alert_fired_email.html.haml

 %p
   An alert has been triggered in #{@alert.project_full_path}.
 
+- if description = @alert.description
+  %p
+    Description: #{description}
+
 - if env_name = @alert.environment_name
   %p
     Environment: #{env_name}

ee/app/views/notify/prometheus_alert_fired_email.text.erb

 An alert has been triggered in <%= @alert.project_full_path %>.
 
+<% if description = @alert.description %>
+Description: <%= description %>
+<% end %>
+
 <% if env_name = @alert.environment_name %>
 Environment: <%= env_name %>
 <% end %>

ee/changelogs/unreleased/pl-mail-external-alerts.yml

+---
+title: Enable mails for external alerts
+merge_request: 9457
+author:
+type: added

ee/lib/gitlab/alerting/alert.rb

@@ -15,12 +15,24 @@ module Gitlab
         end
       end
 
+      def title
+        strong_memoize(:title) do
+          parse_title_from_payload
+        end
+      end
+
+      def description
+        strong_memoize(:description) do
+          parse_description_from_payload
+        end
+      end
+
       def environment
         gitlab_alert&.environment
       end
 
       def valid?
-        project && gitlab_alert
+        project && title
       end
 
       def present
@@ -35,6 +47,16 @@ module Gitlab
 
         project.prometheus_alerts.for_metric(metric_id).first
       end
+
+      def parse_title_from_payload
+        gitlab_alert&.title ||
+          payload&.dig('annotations', 'title') ||
+          payload&.dig('annotations', 'summary')
+      end
+
+      def parse_description_from_payload
+        payload&.dig('annotations', 'description')
+      end
     end
   end
 end

ee/spec/lib/gitlab/alerting/alert_spec.rb

@@ -28,6 +28,12 @@ describe Gitlab::Alerting::Alert do
         expect(alert.environment).to eq(gitlab_alert.environment)
       end
 
+      it 'prefers gitlab_alert\'s title over annotated title' do
+        payload['annontations'] = { 'title' => 'other title' }
+
+        expect(alert.title).to eq(gitlab_alert.title)
+      end
+
       it 'is valid' do
         expect(alert).to be_valid
       end

ee/spec/mailers/ee/emails/projects_spec.rb

@@ -46,7 +46,7 @@ describe EE::Emails::Projects do
       it_behaves_like 'a user cannot unsubscribe through footer link'
 
       it 'has expected subject' do
-        is_expected.to have_subject(/Alert: #{environment.name} #{title}/)
+        is_expected.to have_subject("#{project.name} | Alert: #{environment.name} #{title} for 5 minutes")
       end
 
       it 'has expected content' do
@@ -77,5 +77,51 @@ describe EE::Emails::Projects do
 
       it_behaves_like 'no email'
     end
+
+    context 'with an external alert' do
+      let(:title) { 'alert title' }
+
+      let(:metrics_url) do
+        metrics_project_environments_url(project)
+      end
+
+      let(:alert_params) do
+        {
+          'annotations' => {
+            'title' => title
+          }
+        }
+      end
+
+      it_behaves_like 'an email sent from GitLab'
+      it_behaves_like 'it should not have Gmail Actions links'
+      it_behaves_like 'a user cannot unsubscribe through footer link'
+
+      it 'has expected subject' do
+        is_expected.to have_subject("#{project.name} | Alert: #{title}")
+      end
+
+      it 'has expected content' do
+        is_expected.to have_body_text('An alert has been triggered')
+        is_expected.to have_body_text(project.full_path)
+        is_expected.not_to have_body_text('Description:')
+        is_expected.not_to have_body_text('Environment:')
+        is_expected.not_to have_body_text('Metric:')
+        is_expected.to have_body_text(metrics_url)
+      end
+
+      context 'with annotated description' do
+        let(:description) { 'description' }
+
+        before do
+          alert_params['annotations']['description'] = description
+        end
+
+        it 'shows the description' do
+          is_expected.to have_body_text('Description:')
+          is_expected.to have_body_text(description)
+        end
+      end
+    end
   end
 end