Bring back Rugged implementation of find_commit

This brings back some of the changes in
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/20339.

For users using Gitaly on top of NFS, accessing the Git data directly
via Rugged is more performant than Gitaly. This merge request introduces
the feature flag `rugged_find_commit` to activate Rugged paths.

There are also Rake tasks `gitlab:features:enable_rugged` and
`gitlab:features:disable_rugged` to enable/disable these feature
flags altogether.

Part of four Rugged changes identified in
https://gitlab.com/gitlab-org/gitlab-ce/issues/57317.

3 files changed, 33 insertions, 2 deletions

diff --git a/spec/lib/gitlab/git/commit_spec.rb b/spec/lib/gitlab/git/commit_spec.rb
index 2611ebed25b..3fb41a626b2 100644
--- a/spec/lib/gitlab/git/commit_spec.rb
+++ b/spec/lib/gitlab/git/commit_spec.rb
@@ -112,7 +112,7 @@ describe Gitlab::Git::Commit, :seed_helper do
   end
 
   context 'Class methods' do
-    describe '.find' do
+    shared_examples '.find' do
       it "should return first head commit if without params" do
         expect(described_class.last(repository).id).to eq(
           rugged_repo.head.target.oid
@@ -154,6 +154,20 @@ describe Gitlab::Git::Commit, :seed_helper do
       end
     end
 
+    describe '.find with Gitaly enabled' do
+      it_should_behave_like '.find'
+    end
+
+    describe '.find with Rugged enabled', :enable_rugged do
+      it 'calls out to the Rugged implementation' do
+        allow_any_instance_of(Rugged).to receive(:rev_parse).with(SeedRepo::Commit::ID).and_call_original
+
+        described_class.find(repository, SeedRepo::Commit::ID)
+      end
+
+      it_should_behave_like '.find'
+    end
+
     describe '.last_for_path' do
       context 'no path' do
         subject { described_class.last_for_path(repository, 'master') }
diff --git a/spec/lib/gitlab/gitaly_client/storage_settings_spec.rb b/spec/lib/gitlab/gitaly_client/storage_settings_spec.rb
index c89913ec8e9..bb10be2a4dc 100644
--- a/spec/lib/gitlab/gitaly_client/storage_settings_spec.rb
+++ b/spec/lib/gitlab/gitaly_client/storage_settings_spec.rb
@@ -26,4 +26,14 @@ describe Gitlab::GitalyClient::StorageSettings do
       end
     end
   end
+
+  describe '.disk_access_denied?' do
+    it 'return false when Rugged is enabled', :enable_rugged do
+      expect(described_class.disk_access_denied?).to be_falsey
+    end
+
+    it 'returns true' do
+      expect(described_class.disk_access_denied?).to be_truthy
+    end
+  end
 end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 97e7a019222..e8d7b18bf04 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -115,10 +115,17 @@ RSpec.configure do |config|
     TestEnv.clean_test_path
   end
 
-  config.before do
+  config.before do |example|
     # Enable all features by default for testing
     allow(Feature).to receive(:enabled?) { true }
 
+    enabled = example.metadata[:enable_rugged].present?
+
+    # Disable Rugged features by default
+    Gitlab::Git::RuggedImpl::Repository::FEATURE_FLAGS.each do |flag|
+      allow(Feature).to receive(:enabled?).with(flag).and_return(enabled)
+    end
+
     # The following can be removed when we remove the staged rollout strategy
     # and we can just enable it using instance wide settings
     # (ie. ApplicationSetting#auto_devops_enabled)