Allow chat notifications only for the default branch

Right now, it once  a chat notifacation service has been enabled, there
is no way to limit the branches which trigger a notification. Instead of
allowing the user to specify the list, I opted to let the user check the
box if they'd only want to be notified of the default branch.

Tags are uneffected by this change.

4 files changed, 41 insertions, 25 deletions

diff --git a/app/models/project_services/chat_notification_service.rb b/app/models/project_services/chat_notification_service.rb
index 200be99f36b..1a26d97283e 100644
--- a/app/models/project_services/chat_notification_service.rb
+++ b/app/models/project_services/chat_notification_service.rb
@@ -6,7 +6,7 @@ class ChatNotificationService < Service
   default_value_for :category, 'chat'
 
   prop_accessor :webhook, :username, :channel
-  boolean_accessor :notify_only_broken_pipelines
+  boolean_accessor :notify_only_broken_pipelines, :notify_only_default_branch
 
   validates :webhook, presence: true, url: true, if: :activated?
 
@@ -17,6 +17,7 @@ class ChatNotificationService < Service
     if properties.nil?
       self.properties = {}
       self.notify_only_broken_pipelines = true
+      self.notify_only_default_branch = false
     end
   end
 
@@ -29,6 +30,19 @@ class ChatNotificationService < Service
        pipeline wiki_page]
   end
 
+  def fields
+    default_fields + build_event_channels
+  end
+
+  def default_fields
+    [
+      { type: 'text', name: 'webhook', placeholder: "e.g. #{webhook_placeholder}" },
+      { type: 'text', name: 'username', placeholder: 'e.g. GitLab' },
+      { type: 'checkbox', name: 'notify_only_broken_pipelines' },
+      { type: 'checkbox', name: 'notify_only_default_branch' },
+    ]
+  end
+
   def execute(data)
     return unless supported_events.include?(data[:object_kind])
     return unless webhook.present?
@@ -123,6 +137,20 @@ class ChatNotificationService < Service
   end
 
   def should_pipeline_be_notified?(data)
+    notify_for_branch(data) && notify_for_pipeline(data)
+  end
+
+  def notify_for_branch(data)
+    ref_type = data[:object_attributes][:tag] ? 'tag' : 'branch'
+
+    if ref_type == 'branch' && notify_only_default_branch
+      data[:object_attributes][:ref] == project.default_branch
+    else
+      true
+    end
+  end
+
+  def notify_for_pipeline(data)
     case data[:object_attributes][:status]
     when 'success'
       !notify_only_broken_pipelines?
diff --git a/app/models/project_services/mattermost_service.rb b/app/models/project_services/mattermost_service.rb
index 1156d050622..0362ed172c7 100644
--- a/app/models/project_services/mattermost_service.rb
+++ b/app/models/project_services/mattermost_service.rb
@@ -22,19 +22,11 @@ class MattermostService < ChatNotificationService
     </ol>'
   end
 
-  def fields
-    default_fields + build_event_channels
-  end
-
-  def default_fields
-    [
-      { type: 'text', name: 'webhook', placeholder: 'e.g. http://mattermost_host/hooks/…' },
-      { type: 'text', name: 'username', placeholder: 'e.g. GitLab' },
-      { type: 'checkbox', name: 'notify_only_broken_pipelines' },
-    ]
-  end
-
   def default_channel_placeholder
     "Channel handle (e.g. town-square)"
   end
+
+  def webhook_placeholder
+    'http://mattermost.example.com/hooks/…'
+  end
 end
diff --git a/app/models/project_services/slack_service.rb b/app/models/project_services/slack_service.rb
index b657db6f9ee..71da0af75f6 100644
--- a/app/models/project_services/slack_service.rb
+++ b/app/models/project_services/slack_service.rb
@@ -21,19 +21,11 @@ class SlackService < ChatNotificationService
     </ol>'
   end
 
-  def fields
-    default_fields + build_event_channels
-  end
-
-  def default_fields
-    [
-      { type: 'text', name: 'webhook', placeholder: 'e.g. https://hooks.slack.com/services/…' },
-      { type: 'text', name: 'username', placeholder: 'e.g. GitLab' },
-      { type: 'checkbox', name: 'notify_only_broken_pipelines' },
-    ]
-  end
-
   def default_channel_placeholder
     "Channel name (e.g. general)"
   end
+
+  def webhook_placeholder
+    'https://hooks.slack.com/services/…'
+  end
 end
diff --git a/changelogs/unreleased/zj-chat-notification-default-branch.yml b/changelogs/unreleased/zj-chat-notification-default-branch.yml
new file mode 100644
index 00000000000..fa0052d5034
--- /dev/null
+++ b/changelogs/unreleased/zj-chat-notification-default-branch.yml
@@ -0,0 +1,4 @@
+---
+title: Only send chat notifications for the default branch
+merge_request:
+author: