Client implementation for Licensee#key

Part of the migration as tracked in: gitlab-org/gitaly#1026

app/models/repository.rb

@@ -589,15 +589,7 @@ class Repository
   def license_key
     return unless exists?
-    # The licensee gem creates a Rugged object from the path:
-    # https://github.com/benbalter/licensee/blob/v8.7.0/lib/licensee/projects/git_project.rb
-    begin
-      Licensee.license(path).try(:key)
-    # Normally we would rescue Rugged::Error, but that is banned by lint-rugged
-    # and we need to migrate this endpoint to Gitaly:
-    # https://gitlab.com/gitlab-org/gitaly/issues/1026
-    rescue
-    end
+    raw_repository.license_short_name
   end
   cache_method :license_key

lib/gitlab/git/repository.rb

@@ -1032,6 +1032,21 @@ module Gitlab
         end
       end
+      def license_short_name
+        gitaly_migrate(:license_short_name) do |is_enabled|
+          if is_enabled
+            gitaly_repository_client.license_short_name
+          else
+            begin
+              # The licensee gem creates a Rugged object from the path:
+              # https://github.com/benbalter/licensee/blob/v8.7.0/lib/licensee/projects/git_project.rb
+              Licensee.license(path).try(:key)
+            rescue Rugged::Error
+            end
+          end
+        end
+      end
+
       def with_repo_branch_commit(start_repository, start_branch_name)
         Gitlab::Git.check_namespace!(start_repository)
         start_repository = RemoteRepository.new(start_repository) unless start_repository.is_a?(RemoteRepository)

lib/gitlab/gitaly_client/repository_service.rb

@@ -249,6 +249,14 @@ module Gitlab
         raise Gitlab::Git::OSError.new(response.error) unless response.error.empty?
       end
+
+      def license_short_name
+        request = Gitaly::FindLicenseRequest.new(repository: @gitaly_repo)
+
+        response = GitalyClient.call(@storage, :repository_service, :find_license, request, timeout: GitalyClient.fast_timeout)
+
+        response.license_short_name.presence
+      end
     end
   end
 end

spec/lib/gitlab/git/repository_spec.rb

@@ -1649,6 +1649,35 @@ describe Gitlab::Git::Repository, seed_helper: true do
     end
   end
+  describe '#license_short_name' do
+    shared_examples 'acquiring the Licensee license key' do
+      subject { repository.license_short_name }
+
+      context 'when no license file can be found' do
+        let(:project) { create(:project, :repository) }
+        let(:repository) { project.repository.raw_repository }
+
+        before do
+          project.repository.delete_file(project.owner, 'LICENSE', message: 'remove license', branch_name: 'master')
+        end
+
+        it { is_expected.to be_nil }
+      end
+
+      context 'when an mit license is found' do
+        it { is_expected.to eq('mit') }
+      end
+    end
+
+    context 'when gitaly is enabled' do
+      it_behaves_like 'acquiring the Licensee license key'
+    end
+
+    context 'when gitaly is disabled', :disable_gitaly do
+      it_behaves_like 'acquiring the Licensee license key'
+    end
+  end
+
   describe '#with_repo_branch_commit' do
     context 'when comparing with the same repository' do
       let(:start_repository) { repository }