Implement pipeline size limit class

app/models/ci/pipeline.rb

@@ -325,6 +325,10 @@ module Ci
       @stage_seeds ||= config_processor.stage_seeds(self)
     end
 
+    def seeds_size
+      @seeds_size ||= stage_seeds.sum(&:size)
+    end
+
     def has_kubernetes_active?
       project.kubernetes_service&.active?
     end

ee/lib/ee/gitlab/ci/pipeline/quota/size.rb

+module EE
+  module Gitlab
+    module Ci
+      module Pipeline
+        module Quota
+          class Size < Ci::Limit
+            include ActionView::Helpers::TextHelper
+
+            def initialize(namespace, pipeline)
+              @namespace = namespace
+              @pipeline = pipeline
+            end
+
+            def enabled?
+              @namespace.max_pipeline_size > 0
+            end
+
+            def exceeded?
+              return false unless enabled?
+
+              excessive_seeds_count > 0
+            end
+
+            def message
+              return unless exceeded?
+
+              'Pipeline size limit exceeded by ' \
+                "#{pluralize(excessive_seeds_count, 'job')}!"
+            end
+
+            private
+
+            def excessive_seeds_count
+              @excessive ||= @pipeline.seeds_size - @namespace.max_pipeline_size
+            end
+          end
+        end
+      end
+    end
+  end
+end

lib/gitlab/ci/stage/seed.rb

@@ -3,7 +3,9 @@ module Gitlab
     module Stage
       class Seed
         attr_reader :pipeline
+
         delegate :project, to: :pipeline
+        delegate :size, to: :@jobs
 
         def initialize(pipeline, stage, jobs)
           @pipeline = pipeline

spec/ee/spec/lib/gitlab/ci/pipeline/quota/size_spec.rb

+require 'spec_helper'
+
+describe EE::Gitlab::Ci::Pipeline::Quota::Size do
+  set(:namespace) { create(:namespace, plan: EE::Namespace::GOLD_PLAN) }
+  set(:project) { create(:project, namespace: namespace) }
+
+  let(:pipeline) { build_stubbed(:ci_pipeline, project: project) }
+  let(:limit) { described_class.new(namespace, pipeline) }
+
+  shared_context 'pipeline size limit exceeded' do
+    let(:pipeline) do
+      config = { rspec: { script: 'rspec' },
+                 spinach: { script: 'spinach' } }
+
+      build(:ci_pipeline, project: project, config: config)
+    end
+
+    before do
+      namespace.plan.update_column(:pipeline_size_limit, 1)
+    end
+  end
+
+  shared_context 'pipeline size limit not exceeded' do
+    let(:pipeline) { build(:ci_pipeline_with_one_job, project: project) }
+
+    before do
+      namespace.plan.update_column(:pipeline_size_limit, 2)
+    end
+  end
+
+  describe '#enabled?' do
+    context 'when limit is enabled in plan' do
+      before do
+        namespace.plan.update_column(:pipeline_size_limit, 10)
+      end
+
+      it 'is enabled' do
+        expect(limit).to be_enabled
+      end
+    end
+
+    context 'when limit is not enabled' do
+      before do
+        namespace.plan.update_column(:pipeline_size_limit, 0)
+      end
+
+      it 'is not enabled' do
+        expect(limit).not_to be_enabled
+      end
+    end
+  end
+
+  describe '#exceeded?' do
+    context 'when limit is exceeded' do
+      include_context 'pipeline size limit exceeded'
+
+      it 'is exceeded' do
+        expect(limit).to be_exceeded
+      end
+    end
+
+    context 'when limit is not exceeded' do
+      include_context 'pipeline size limit not exceeded'
+
+      it 'is not exceeded' do
+        expect(limit).not_to be_exceeded
+      end
+    end
+  end
+
+  describe '#message' do
+    context 'when limit is exceeded' do
+      include_context 'pipeline size limit exceeded'
+
+      it 'returns infor about pipeline size limit exceeded' do
+        expect(limit.message)
+          .to eq "Pipeline size limit exceeded by 1 job!"
+      end
+    end
+  end
+end