Label filter for chat notification services

Adds a configuration to only notify
chat services for specific labels

app/controllers/concerns/service_params.rb

@@ -12,6 +12,7 @@ module ServiceParams
     :api_version,
     :bamboo_url,
     :branches_to_be_notified,
+    :labels_to_be_notified,
     :build_key,
     :build_type,
     :ca_pem,

app/models/project_services/chat_notification_service.rb

@@ -11,11 +11,13 @@ class ChatNotificationService < Service
     tag_push pipeline wiki_page deployment
   ].freeze
 
+  SUPPORTED_EVENTS_FOR_LABEL_FILTER = %w[issue confidential_issue merge_request note confidential_note].freeze
+
   EVENT_CHANNEL = proc { |event| "#{event}_channel" }
 
   default_value_for :category, 'chat'
 
-  prop_accessor :webhook, :username, :channel, :branches_to_be_notified
+  prop_accessor :webhook, :username, :channel, :branches_to_be_notified, :labels_to_be_notified
 
   # Custom serialized properties initialization
   prop_accessor(*SUPPORTED_EVENTS.map { |event| EVENT_CHANNEL[event] })
@@ -62,12 +64,16 @@ class ChatNotificationService < Service
       { type: 'text', name: 'webhook', placeholder: "e.g. #{webhook_placeholder}", required: true }.freeze,
       { type: 'text', name: 'username', placeholder: 'e.g. GitLab' }.freeze,
       { type: 'checkbox', name: 'notify_only_broken_pipelines' }.freeze,
-      { type: 'select', name: 'branches_to_be_notified', choices: branch_choices }.freeze
+      { type: 'select', name: 'branches_to_be_notified', choices: branch_choices }.freeze,
+      { type: 'text', name: 'labels_to_be_notified', placeholder: 'e.g. ~backend', help: 'Only supported for issue, merge request and note events.' }.freeze
     ].freeze
   end
 
   def execute(data)
     return unless supported_events.include?(data[:object_kind])
+
+    return unless notify_label?(data)
+
     return unless webhook.present?
 
     object_kind = data[:object_kind]
@@ -114,6 +120,22 @@ class ChatNotificationService < Service
 
   private
 
+  def labels_to_be_notified_list
+    return [] if labels_to_be_notified.nil?
+
+    labels_to_be_notified.delete('~').split(',').map(&:strip)
+  end
+
+  def notify_label?(data)
+    return true unless SUPPORTED_EVENTS_FOR_LABEL_FILTER.include?(data[:object_kind]) && labels_to_be_notified.present?
+
+    issue_labels = data.dig(:issue, :labels) || []
+    merge_request_labels = data.dig(:merge_request, :labels) || []
+    label_titles = (issue_labels + merge_request_labels).pluck(:title)
+
+    (labels_to_be_notified_list & label_titles).any?
+  end
+
   # every notifier must implement this independently
   def notify(message, opts)
     raise NotImplementedError

changelogs/unreleased/chat_notification_label_support.yml

+---
+title: Add chat notification label support
+merge_request: 52105
+author:
+type: added

doc/user/project/integrations/mattermost.md

@@ -59,5 +59,6 @@ At the end, fill in your Mattermost details:
 | **Username** | Optional username which can be on messages sent to Mattermost. Fill this in if you want to change the username of the bot. |
 | **Notify only broken pipelines** | If you choose to enable the **Pipeline** event and you want to be only notified about failed pipelines. |
 | **Branches to be notified** | Select which types of branches to send notifications for. |
+| **Labels to be notified** | Optional labels that the issue or merge request must have in order to trigger a notification. Leave blank to get all notifications. |
 
-![Mattermost configuration](img/mattermost_configuration.png)
+![Mattermost configuration](img/mattermost_configuration_v2.png)

doc/user/project/integrations/slack.md

@@ -45,6 +45,7 @@ separately configured [Slack slash commands](slack_slash_commands.md).
 1. Select the **Notify only broken pipelines** check box to only notify on failures.
 1. In the **Branches to be notified** select box, choose which types of branches
    to send notifications for.
+1. Leave the **Labels to be notified** field blank to get all notifications or add labels that the issue or merge request must have in order to trigger a notification.
 1. Click **Test settings and save changes**.
 
 Your Slack team now starts receiving GitLab event notifications as configured.

spec/models/project_services/chat_notification_service_spec.rb

@@ -75,6 +75,39 @@ RSpec.describe ChatNotificationService do
       end
     end
 
+    context 'when the data object has a label' do
+      let(:label) { create(:label, project: project, name: 'Bug')}
+      let(:issue) { create(:labeled_issue, project: project, labels: [label]) }
+      let(:note) { create(:note, noteable: issue, project: project)}
+      let(:data) { Gitlab::DataBuilder::Note.build(note, user) }
+
+      it 'notifies the chat service' do
+        expect(chat_service).to receive(:notify).with(any_args)
+
+        chat_service.execute(data)
+      end
+
+      context 'and the chat_service has a label filter that does not matches the label' do
+        subject(:chat_service) { described_class.new(labels_to_be_notified: '~some random label') }
+
+        it 'does not notify the chat service' do
+          expect(chat_service).not_to receive(:notify)
+
+          chat_service.execute(data)
+        end
+      end
+
+      context 'and the chat_service has a label filter that matches the label' do
+        subject(:chat_service) { described_class.new(labels_to_be_notified: '~Backend, ~Bug') }
+
+        it 'notifies the chat service' do
+          expect(chat_service).to receive(:notify).with(any_args)
+
+          chat_service.execute(data)
+        end
+      end
+    end
+
     context 'with "channel" property' do
       before do
         allow(chat_service).to receive(:channel).and_return(channel)