Handle maximum pages artifacts size correctly

app/services/projects/update_pages_service.rb

@@ -130,7 +130,9 @@ module Projects
     end
 
     def max_size
-      current_application_settings.max_pages_size.megabytes || MAX_SIZE
+      current_application_settings.max_pages_size.megabytes.tap do |maximum|
+        return MAX_SIZE if maximum.zero? || maximum > MAX_SIZE
+      end
     end
 
     def tmp_path

spec/services/projects/update_pages_service_spec.rb

@@ -96,6 +96,78 @@ describe Projects::UpdatePagesService do
     expect(execute).not_to eq(:success)
   end
 
+  describe 'maximum pages artifacts size' do
+    let(:metadata) { spy('metadata') }
+
+    before do
+      file = fixture_file_upload(Rails.root + 'spec/fixtures/pages.zip')
+      metafile = fixture_file_upload(Rails.root + 'spec/fixtures/pages.zip.meta')
+
+      build.update_attributes(artifacts_file: file)
+      build.update_attributes(artifacts_metadata: metafile)
+
+      allow(build).to receive(:artifacts_metadata_entry)
+        .and_return(metadata)
+    end
+
+    shared_examples 'pages size limit exceeded' do
+      it 'limits the maximum size of gitlab pages' do
+        subject.execute
+
+        expect(deploy_status.description)
+          .to match(/artifacts for pages are too large/)
+      end
+    end
+
+    context 'when maximum pages size is set to zero' do
+      before do
+        stub_application_setting(max_pages_size: 0)
+      end
+
+      context 'when page size does not exceed internal maximum' do
+        before do
+          allow(metadata).to receive(:total_size).and_return(200.megabytes)
+        end
+
+        it 'updates pages correctly' do
+          subject.execute
+
+          expect(deploy_status.description).not_to be_present
+        end
+      end
+
+      context 'when pages size does exceed internal maximum' do
+        before do
+          allow(metadata).to receive(:total_size).and_return(2.terabytes)
+        end
+
+        it_behaves_like 'pages size limit exceeded'
+      end
+    end
+
+    context 'when pages size is greater than max size setting' do
+      before do
+        stub_application_setting(max_pages_size: 200)
+        allow(metadata).to receive(:total_size).and_return(201.megabytes)
+      end
+
+      it_behaves_like 'pages size limit exceeded'
+    end
+
+    context 'when max size setting is greater than internal max size' do
+      before do
+        stub_application_setting(max_pages_size: 3.terabytes / 1.megabyte)
+        allow(metadata).to receive(:total_size).and_return(2.terabytes)
+      end
+
+      it_behaves_like 'pages size limit exceeded'
+    end
+  end
+
+  def deploy_status
+    GenericCommitStatus.find_by(name: 'pages:deploy');
+  end
+
   def execute
     subject.execute[:status]
   end