Added atom feed for tags

app/controllers/projects/tags_controller.rb

@@ -17,6 +17,11 @@ class Projects::TagsController < Projects::ApplicationController
     tag_names = @tags.map(&:name)
     @tags_pipelines = @project.pipelines.latest_successful_for_refs(tag_names)
     @releases = project.releases.where(tag: tag_names)
+
+    respond_to do |format|
+      format.html
+      format.atom { render layout: 'xml.atom' }
+    end
   end
 
   def show

app/views/projects/tags/_tag.atom.builder

+commit = @repository.commit(tag.dereferenced_target)
+release = @releases.find { |r| r.tag == tag.name }
+tag_url = project_tag_url(@project, tag.name)
+
+if commit
+  xml.entry do
+    xml.id      tag_url
+    xml.link    href: tag_url
+    xml.title   truncate(tag.name, length: 80)
+    xml.summary strip_gpg_signature(tag.message)
+    xml.content markdown_field(release, :description), type: 'html'
+    xml.updated release.updated_at.xmlschema if release
+    xml.media   :thumbnail, width: '40', height: '40', url: image_url(avatar_icon_for_email(commit.author_email))
+    xml.author do |author|
+      xml.name  commit.author_name
+      xml.email commit.author_email
+    end
+  end
+end

app/views/projects/tags/index.atom.builder

+xml.title   "#{@project.name} tags"
+xml.link    href: project_tags_url(@project, @ref, rss_url_options), rel: 'self', type: 'application/atom+xml'
+xml.link    href: project_tags_url(@project, @ref), rel: 'alternate', type: 'text/html'
+xml.id      project_tags_url(@project, @ref)
+xml.updated @releases.first.updated_at.xmlschema if @releases.any?
+
+xml << render(partial: 'tag', collection: @tags) if @tags.any?

app/views/projects/tags/index.html.haml

 - @no_container = true
 - @sort ||= sort_value_recently_updated
 - page_title s_('TagsPage|Tags')
+= content_for :meta_tags do
+  = auto_discovery_link_tag(:atom, project_tags_url(@project, rss_url_options), title: "#{@project.name} tags")
 
 .flex-list{ class: container_class }
   .top-area.adjust
@@ -25,6 +27,8 @@
       - if can?(current_user, :push_code, @project)
         = link_to new_project_tag_path(@project), class: 'btn btn-create new-tag-btn' do
           = s_('TagsPage|New tag')
+      = link_to project_tags_path(@project, rss_url_options), title: _("Tags feed"), class: 'btn rss-btn has-tooltip' do
+        = icon("rss")
 
   = render_if_exists 'projects/commits/mirror_status'
 

changelogs/unreleased/fj-2635-enable-rss-for-tags.yml

+---
+title: Added atom feed for tags
+merge_request: 21428
+author:
+type: added

locale/gitlab.pot

@@ -5411,6 +5411,9 @@ msgstr[1] ""
 msgid "Tags"
 msgstr ""
 
+msgid "Tags feed"
+msgstr ""
+
 msgid "Tags:"
 msgstr ""
 

spec/features/projects/tags/user_views_tags_spec.rb

+# frozen_string_literal: true
+require 'spec_helper'
+
+describe 'User views tags', :feature do
+  context 'rss' do
+    shared_examples 'has access to the tags RSS feed' do
+      it do
+        visit project_tags_path(project, format: :atom)
+
+        expect(page).to have_gitlab_http_status(200)
+      end
+    end
+
+    shared_examples 'does not have access to the tags RSS feed' do
+      it do
+        visit project_tags_path(project, format: :atom)
+
+        expect(page).to have_gitlab_http_status(401)
+      end
+    end
+
+    context 'when project public' do
+      let(:project) { create(:project, :repository, visibility_level: Gitlab::VisibilityLevel::PUBLIC) }
+
+      context 'when user signed in' do
+        let(:user) { create(:user) }
+
+        before do
+          project.add_developer(user)
+          sign_in(user)
+          visit project_tags_path(project)
+        end
+
+        it_behaves_like "it has an RSS button with current_user's feed token"
+        it_behaves_like "an autodiscoverable RSS feed with current_user's feed token"
+        it_behaves_like 'has access to the tags RSS feed'
+      end
+
+      context 'when user signed out' do
+        before do
+          visit project_tags_path(project)
+        end
+
+        it_behaves_like 'it has an RSS button without a feed token'
+        it_behaves_like 'an autodiscoverable RSS feed without a feed token'
+        it_behaves_like 'has access to the tags RSS feed'
+      end
+    end
+
+    context 'when project is not public' do
+      let(:project) { create(:project, :repository, visibility_level: Gitlab::VisibilityLevel::PRIVATE) }
+
+      context 'when user signed in' do
+        let(:user) { create(:user) }
+
+        before do
+          project.add_developer(user)
+          sign_in(user)
+        end
+
+        it_behaves_like 'has access to the tags RSS feed'
+      end
+
+      context 'when user signed out' do
+        it_behaves_like 'does not have access to the tags RSS feed'
+      end
+    end
+  end
+end