Introduce ci_builds.artifacts_sizes as JSON:

We store the sizes as a hash from path to bytes like:

``` ruby
{'ci_artifacts.txt' => 27,
 'other_artifacts_0.1.2/another-subdirectory/banana_sample.gif' =>
71759,
 'other_artifacts_0.1.2/doc_sample.txt' => 1314,
 'rails_sample.jpg' => 35255,
 'tests_encoding/utf8 test dir ✓/regular_file_2' => 7}
```

So that it's easier to access than reading gzip file again.

app/models/ci/build.rb

@@ -5,6 +5,7 @@ module Ci
     belongs_to :erased_by, class_name: 'User'
 
     serialize :options
+    serialize :artifacts_sizes, JSON
 
     validates :coverage, numericality: true, allow_blank: true
     validates_presence_of :ref
@@ -328,8 +329,19 @@ module Ci
       artifacts? && artifacts_metadata.exists?
     end
 
+    def artifacts_metadata_sizes
+      return unless artifacts_metadata?
+
+      entries = new_artifacts_metadata('', recursive: true).find_entries!
+
+      entries.inject({}) do |result, (path, metadata)|
+        result[path] = metadata[:size] if metadata[:size]
+        result
+      end
+    end
+
     def artifacts_metadata_entry(path, **options)
-      Gitlab::Ci::Build::Artifacts::Metadata.new(artifacts_metadata.path, path, **options).to_entry
+      new_artifacts_metadata(path, **options).to_entry
     end
 
     def erase_artifacts!
@@ -375,6 +387,13 @@ module Ci
 
     private
 
+    def new_artifacts_metadata(path, **options)
+      Gitlab::Ci::Build::Artifacts::Metadata.new(
+        artifacts_metadata.path,
+        path,
+        **options)
+    end
+
     def erase_trace!
       self.trace = nil
     end

db/migrate/20160628085157_add_artifacts_sizes_to_ci_builds.rb

+# See http://doc.gitlab.com/ce/development/migration_style_guide.html
+# for more information on how to write migrations for GitLab.
+
+class AddArtifactsSizesToCiBuilds < ActiveRecord::Migration
+  include Gitlab::Database::MigrationHelpers
+
+  def change
+    # Or :json if under PostgreSQL?
+    add_column(:ci_builds, :artifacts_sizes, :text)
+  end
+end

lib/ci/api/builds.rb

@@ -147,6 +147,7 @@ module Ci
           build.artifacts_file = artifacts
           build.artifacts_metadata = metadata
           build.artifacts_expire_in = params['expire_in']
+          build.artifacts_sizes = build.artifacts_metadata_sizes
 
           if build.save
             present(build, with: Entities::BuildDetails)

spec/requests/ci/api/builds_spec.rb

@@ -309,7 +309,7 @@ describe Ci::API::API do
             shared_examples 'post artifact' do
               it 'updates successfully' do
                 response_filename =
-                  json_response["artifacts_file"]["filename"]
+                  json_response['artifacts_file']['filename']
 
                 expect(response).to have_http_status(201)
                 expect(response_filename).to eq(file_upload.original_filename)
@@ -344,10 +344,14 @@ describe Ci::API::API do
 
           context 'should post artifacts file and metadata file' do
             let!(:artifacts) { file_upload }
-            let!(:metadata) { file_upload2 }
+            let!(:metadata) do
+              fixture_file_upload(
+                Rails.root + 'spec/fixtures/ci_build_artifacts_metadata.gz')
+            end
 
             let(:stored_artifacts_file) { build.reload.artifacts_file.file }
             let(:stored_metadata_file) { build.reload.artifacts_metadata.file }
+            let(:stored_artifacts_sizes) { build.reload.artifacts_sizes }
 
             before do
               post(post_url, post_data, headers_with_token)
@@ -365,6 +369,12 @@ describe Ci::API::API do
                 expect(response).to have_http_status(201)
                 expect(stored_artifacts_file.original_filename).to eq(artifacts.original_filename)
                 expect(stored_metadata_file.original_filename).to eq(metadata.original_filename)
+                expect(stored_artifacts_sizes).to eq(
+                  'ci_artifacts.txt' => 27,
+                  'other_artifacts_0.1.2/another-subdirectory/banana_sample.gif' => 71759,
+                  'other_artifacts_0.1.2/doc_sample.txt' => 1314,
+                  'rails_sample.jpg' => 35255,
+                  'tests_encoding/utf8 test dir ✓/regular_file_2' => 7)
               end
             end