diff --git a/Dangerfile b/Dangerfile
index cc6ebc27d4e9cf4f150e7649339e891c90231df4..cba7226d4b9aa4b9dd72c126d71cfb7af12ae37a 100644
--- a/Dangerfile
+++ b/Dangerfile
@@ -6,6 +6,7 @@ require_relative 'lib/gitlab/danger/request_helper'
danger.import_plugin('danger/plugins/helper.rb')
danger.import_plugin('danger/plugins/roulette.rb')
danger.import_plugin('danger/plugins/changelog.rb')
+danger.import_plugin('danger/plugins/sidekiq_queues.rb')
return if helper.release_automation?
diff --git a/danger/plugins/sidekiq_queues.rb b/danger/plugins/sidekiq_queues.rb
new file mode 100644
index 0000000000000000000000000000000000000000..1edeb6da3d59ccc22a86bd3707c30d01fd289cf5
--- /dev/null
+++ b/danger/plugins/sidekiq_queues.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require_relative '../../lib/gitlab/danger/sidekiq_queues'
+
+module Danger
+ class SidekiqQueues < Plugin
+ # Put the helper code somewhere it can be tested
+ include Gitlab::Danger::SidekiqQueues
+ end
+end
diff --git a/danger/sidekiq_queues/Dangerfile b/danger/sidekiq_queues/Dangerfile
new file mode 100644
index 0000000000000000000000000000000000000000..b40be7a486ea5fc897d530347ed01c115fa11c3c
--- /dev/null
+++ b/danger/sidekiq_queues/Dangerfile
@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+SCALABILITY_REVIEW_MESSAGE = <<~MSG
+## Sidekiq queue changes
+
+This merge request contains changes to Sidekiq queues. Please follow the [documentation on changing a queue's urgency](https://docs.gitlab.com/ee/development/sidekiq_style_guide.html#changing-a-queues-urgency).
+MSG
+
+ADDED_QUEUES_MESSAGE = <<~MSG
+These queues were added:
+MSG
+
+CHANGED_QUEUES_MESSAGE = <<~MSG
+These queues had their attributes changed:
+MSG
+
+if sidekiq_queues.added_queue_names.any? || sidekiq_queues.changed_queue_names.any?
+ markdown(SCALABILITY_REVIEW_MESSAGE)
+
+ if sidekiq_queues.added_queue_names.any?
+ markdown(ADDED_QUEUES_MESSAGE + helper.markdown_list(sidekiq_queues.added_queue_names))
+ end
+
+ if sidekiq_queues.changed_queue_names.any?
+ markdown(CHANGED_QUEUES_MESSAGE + helper.markdown_list(sidekiq_queues.changed_queue_names))
+ end
+end
diff --git a/lib/gitlab/danger/sidekiq_queues.rb b/lib/gitlab/danger/sidekiq_queues.rb
new file mode 100644
index 0000000000000000000000000000000000000000..5bf6057d5bae330bf4d038a43ec258eefc42f332
--- /dev/null
+++ b/lib/gitlab/danger/sidekiq_queues.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Gitlab
+ module Danger
+ module SidekiqQueues
+ def changed_queue_files
+ @changed_queue_files ||= git.modified_files.grep(%r{\A(ee/)?app/workers/all_queues\.yml})
+ end
+
+ def added_queue_names
+ @added_queue_names ||= new_queues.keys - old_queues.keys
+ end
+
+ def changed_queue_names
+ @changed_queue_names ||=
+ (new_queues.values_at(*old_queues.keys) - old_queues.values)
+ .map { |queue| queue[:name] }
+ end
+
+ private
+
+ def old_queues
+ @old_queues ||= queues_for(gitlab.base_commit)
+ end
+
+ def new_queues
+ @new_queues ||= queues_for(gitlab.head_commit)
+ end
+
+ def queues_for(branch)
+ changed_queue_files
+ .flat_map { |file| YAML.safe_load(`git show #{branch}:#{file}`, permitted_classes: [Symbol]) }
+ .to_h { |queue| [queue[:name], queue] }
+ end
+ end
+ end
+end
diff --git a/lib/gitlab_danger.rb b/lib/gitlab_danger.rb
index 1c1763454a5a75ef6002b7f6e4d9c4c040cb6069..a98ac9200da90aa3dd3c79e9abf84409d660fb54 100644
--- a/lib/gitlab_danger.rb
+++ b/lib/gitlab_danger.rb
@@ -21,6 +21,7 @@ class GitlabDanger
specs
roulette
ce_ee_vue_templates
+ sidekiq_queues
].freeze
MESSAGE_PREFIX = '==>'.freeze
diff --git a/spec/lib/gitlab/danger/sidekiq_queues_spec.rb b/spec/lib/gitlab/danger/sidekiq_queues_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..afae22eda200db8502437315d65483134a4d3972
--- /dev/null
+++ b/spec/lib/gitlab/danger/sidekiq_queues_spec.rb
@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'rspec-parameterized'
+require_relative 'danger_spec_helper'
+
+require 'gitlab/danger/sidekiq_queues'
+
+RSpec.describe Gitlab::Danger::SidekiqQueues do
+ using RSpec::Parameterized::TableSyntax
+ include DangerSpecHelper
+
+ let(:fake_git) { double('fake-git') }
+ let(:fake_danger) { new_fake_danger.include(described_class) }
+
+ subject(:sidekiq_queues) { fake_danger.new(git: fake_git) }
+
+ describe '#changed_queue_files' do
+ where(:modified_files, :changed_queue_files) do
+ %w(app/workers/all_queues.yml ee/app/workers/all_queues.yml foo) | %w(app/workers/all_queues.yml ee/app/workers/all_queues.yml)
+ %w(app/workers/all_queues.yml ee/app/workers/all_queues.yml) | %w(app/workers/all_queues.yml ee/app/workers/all_queues.yml)
+ %w(app/workers/all_queues.yml foo) | %w(app/workers/all_queues.yml)
+ %w(ee/app/workers/all_queues.yml foo) | %w(ee/app/workers/all_queues.yml)
+ %w(foo) | %w()
+ %w() | %w()
+ end
+
+ with_them do
+ it do
+ allow(fake_git).to receive(:modified_files).and_return(modified_files)
+
+ expect(sidekiq_queues.changed_queue_files).to match_array(changed_queue_files)
+ end
+ end
+ end
+
+ describe '#added_queue_names' do
+ it 'returns queue names added by this change' do
+ old_queues = { post_receive: nil }
+
+ allow(sidekiq_queues).to receive(:old_queues).and_return(old_queues)
+ allow(sidekiq_queues).to receive(:new_queues).and_return(old_queues.merge(merge: nil, process_commit: nil))
+
+ expect(sidekiq_queues.added_queue_names).to contain_exactly(:merge, :process_commit)
+ end
+ end
+
+ describe '#changed_queue_names' do
+ it 'returns names for queues whose attributes were changed' do
+ old_queues = {
+ merge: { name: :merge, urgency: :low },
+ post_receive: { name: :post_receive, urgency: :high },
+ process_commit: { name: :process_commit, urgency: :high }
+ }
+
+ new_queues = old_queues.merge(mailers: { name: :mailers, urgency: :high },
+ post_receive: { name: :post_receive, urgency: :low },
+ process_commit: { name: :process_commit, urgency: :low })
+
+ allow(sidekiq_queues).to receive(:old_queues).and_return(old_queues)
+ allow(sidekiq_queues).to receive(:new_queues).and_return(new_queues)
+
+ expect(sidekiq_queues.changed_queue_names).to contain_exactly(:post_receive, :process_commit)
+ end
+ end
+end