From 54f13b1ec8542dc5085e0367734e8344c2c3d01e Mon Sep 17 00:00:00 2001
From: Stan Hu <stanhu@gmail.com>
Date: Sat, 9 Dec 2017 01:01:42 -0800
Subject: [PATCH] Add rate limiting to guard against excessive scheduling of
 pipelines

---
 .../projects/pipeline_schedules_controller.rb | 11 +++++++
 lib/gitlab/action_rate_limiter.rb             | 31 +++++++++++++++++++
 .../pipeline_schedules_controller_spec.rb     |  2 +-
 3 files changed, 43 insertions(+), 1 deletion(-)
 create mode 100644 lib/gitlab/action_rate_limiter.rb

diff --git a/app/controllers/projects/pipeline_schedules_controller.rb b/app/controllers/projects/pipeline_schedules_controller.rb
index fe77d8eabeb..b7a0a3591cd 100644
--- a/app/controllers/projects/pipeline_schedules_controller.rb
+++ b/app/controllers/projects/pipeline_schedules_controller.rb
@@ -42,6 +42,13 @@ class Projects::PipelineSchedulesController < Projects::ApplicationController
   end
 
   def play
+    limiter = ::Gitlab::ActionRateLimiter.new(action: 'play_pipeline_schedule')
+
+    if limiter.throttled?(throttle_key, 1)
+      flash[:notice] = 'You cannot play this scheduled pipeline at the moment. Please wait a minute.'
+      return redirect_to pipeline_schedules_path(@project)
+    end
+
     job_id = RunPipelineScheduleWorker.perform_async(schedule.id, current_user.id)
 
     flash[:notice] =
@@ -74,6 +81,10 @@ class Projects::PipelineSchedulesController < Projects::ApplicationController
 
   private
 
+  def throttle_key
+    "user:#{current_user.id}:schedule:#{schedule.id}"
+  end
+
   def schedule
     @schedule ||= project.pipeline_schedules.find(params[:id])
   end
diff --git a/lib/gitlab/action_rate_limiter.rb b/lib/gitlab/action_rate_limiter.rb
new file mode 100644
index 00000000000..c3af583a3ed
--- /dev/null
+++ b/lib/gitlab/action_rate_limiter.rb
@@ -0,0 +1,31 @@
+module Gitlab
+  # This class implements a simple rate limiter that can be used to throttle
+  # certain actions. Unlike Rack Attack and Rack::Throttle, which operate at
+  # the middleware level, this can be used at the controller level.
+  class ActionRateLimiter
+    TIME_TO_EXPIRE = 60 # 1 min
+
+    attr_accessor :action, :expiry_time
+
+    def initialize(action:, expiry_time: TIME_TO_EXPIRE)
+      @action = action
+      @expiry_time = expiry_time
+    end
+
+    def increment(key)
+      value = 0
+
+      Gitlab::Redis::Cache.with do |redis|
+        cache_key = "action_rate_limiter:#{action}:#{key}"
+        value = redis.incr(cache_key)
+        redis.expire(cache_key, expiry_time) if value == 1
+      end
+
+      value.to_i
+    end
+
+    def throttled?(key, threshold_value)
+      self.increment(key) > threshold_value
+    end
+  end
+end
diff --git a/spec/controllers/projects/pipeline_schedules_controller_spec.rb b/spec/controllers/projects/pipeline_schedules_controller_spec.rb
index 8888573e882..844c62ef005 100644
--- a/spec/controllers/projects/pipeline_schedules_controller_spec.rb
+++ b/spec/controllers/projects/pipeline_schedules_controller_spec.rb
@@ -366,7 +366,7 @@ describe Projects::PipelineSchedulesController do
     end
   end
 
-  describe 'POST #play' do
+  describe 'POST #play', :clean_gitlab_redis_cache do
     set(:user) { create(:user) }
     let(:ref) { 'master' }