Add metadata about the GitLab server to GraphQL

app/graphql/resolvers/metadata_resolver.rb

+# frozen_string_literal: true
+
+module Resolvers
+  class MetadataResolver < BaseResolver
+    type Types::MetadataType, null: false
+
+    def resolve(**args)
+      { version: Gitlab::VERSION, revision: Gitlab.revision }
+    end
+  end
+end

app/graphql/types/metadata_type.rb

+# frozen_string_literal: true
+
+module Types
+  class MetadataType < ::Types::BaseObject
+    graphql_name 'Metadata'
+
+    field :version, GraphQL::STRING_TYPE, null: false
+    field :revision, GraphQL::STRING_TYPE, null: false
+  end
+end

app/graphql/types/query_type.rb

 # frozen_string_literal: true
 
 module Types
-  class QueryType < BaseObject
+  class QueryType < ::Types::BaseObject
     graphql_name 'Query'
 
     field :project, Types::ProjectType,
@@ -10,6 +10,14 @@ module Types
           description: "Find a project",
           authorize: :read_project
 
+    field :metadata, Types::MetadataType,
+          null: true,
+          resolver: Resolvers::MetadataResolver,
+          description: 'Metadata about GitLab' do |*args|
+
+      authorize :read_instance_metadata
+    end
+
     field :echo, GraphQL::STRING_TYPE, null: false, function: Functions::Echo.new
   end
 end

app/policies/global_policy.rb

@@ -68,6 +68,10 @@ class GlobalPolicy < BasePolicy
     enable :read_users_list
   end
 
+  rule { ~anonymous }.policy do
+    enable :read_instance_metadata
+  end
+
   rule { admin }.policy do
     enable :read_custom_attribute
     enable :update_custom_attribute

changelogs/unreleased/56809-graphql-version-api.yml

+---
+title: Add metadata about the GitLab server to GraphQL
+merge_request: 24636
+author:
+type: added

lib/api/helpers/graphql_helpers.rb

+# frozen_string_literal: true
+
+module API
+  module Helpers
+    # GraphqlHelpers is used by the REST API when it is acting like a client
+    # against the graphql API. Helper code for the graphql server implementation
+    # should be in app/graphql/ or lib/gitlab/graphql/
+    module GraphqlHelpers
+      def conditionally_graphql!(fallback:, query:, context: {}, transform: nil)
+        return fallback.call unless Feature.enabled?(:graphql)
+
+        result = GitlabSchema.execute(query, context: context)
+
+        if transform
+          transform.call(result)
+        else
+          result
+        end
+      end
+    end
+  end
+end

lib/api/version.rb

@@ -2,13 +2,29 @@
 
 module API
   class Version < Grape::API
+    helpers ::API::Helpers::GraphqlHelpers
+
     before { authenticate! }
 
+    METADATA_QUERY = <<~EOF
+      {
+        metadata {
+          version
+          revision
+        }
+      }
+    EOF
+
     desc 'Get the version information of the GitLab instance.' do
       detail 'This feature was introduced in GitLab 8.13.'
     end
     get '/version' do
-      { version: Gitlab::VERSION, revision: Gitlab.revision }
+      conditionally_graphql!(
+        query: METADATA_QUERY,
+        context: { current_user: current_user },
+        transform: ->(result) { result.dig('data', 'metadata') },
+        fallback: -> { { version: Gitlab::VERSION, revision: Gitlab.revision } }
+      )
     end
   end
 end

spec/graphql/resolvers/metadata_resolver_spec.rb

+require 'spec_helper'
+
+describe Resolvers::MetadataResolver do
+  include GraphqlHelpers
+
+  describe '#resolve' do
+    it 'returns version and revision' do
+      expect(resolve(described_class)).to eq(version: Gitlab::VERSION, revision: Gitlab.revision)
+    end
+  end
+end

spec/graphql/types/metadata_type_spec.rb

+require 'spec_helper'
+
+describe GitlabSchema.types['Metadata'] do
+  it { expect(described_class.graphql_name).to eq('Metadata') }
+end

spec/graphql/types/query_type_spec.rb

@@ -5,7 +5,7 @@ describe GitlabSchema.types['Query'] do
     expect(described_class.graphql_name).to eq('Query')
   end
 
-  it { is_expected.to have_graphql_fields(:project, :echo) }
+  it { is_expected.to have_graphql_fields(:project, :echo, :metadata) }
 
   describe 'project field' do
     subject { described_class.fields['project'] }
@@ -20,4 +20,17 @@ describe GitlabSchema.types['Query'] do
       is_expected.to require_graphql_authorizations(:read_project)
     end
   end
+
+  describe 'metadata field' do
+    subject { described_class.fields['metadata'] }
+
+    it 'returns metadata' do
+      is_expected.to have_graphql_type(Types::MetadataType)
+      is_expected.to have_graphql_resolver(Resolvers::MetadataResolver)
+    end
+
+    it 'authorizes with log_in' do
+      is_expected.to require_graphql_authorizations(:read_instance_metadata)
+    end
+  end
 end

spec/policies/global_policy_spec.rb

@@ -181,6 +181,18 @@ describe GlobalPolicy do
     end
   end
 
+  describe 'read instance metadata' do
+    context 'regular user' do
+      it { is_expected.to be_allowed(:read_instance_metadata) }
+    end
+
+    context 'anonymous' do
+      let(:current_user) { nil }
+
+      it { is_expected.not_to be_allowed(:read_instance_metadata) }
+    end
+  end
+
   describe 'read instance statistics' do
     context 'regular user' do
       it { is_expected.to be_allowed(:read_instance_statistics) }

spec/requests/api/graphql/metadata_query_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe 'getting project information' do
+  include GraphqlHelpers
+
+  let(:query) { graphql_query_for('metadata', {}, all_graphql_fields_for('Metadata')) }
+
+  context 'logged in' do
+    it 'returns version and revision' do
+      post_graphql(query, current_user: create(:user))
+
+      expect(graphql_errors).to be_nil
+      expect(graphql_data).to eq(
+        'metadata' => {
+          'version' => Gitlab::VERSION,
+          'revision' => Gitlab.revision
+        }
+      )
+    end
+  end
+
+  context 'anonymous user' do
+    it 'returns nothing' do
+      post_graphql(query, current_user: nil)
+
+      expect(graphql_errors).to be_nil
+      expect(graphql_data).to eq('metadata' => nil)
+    end
+  end
+end

spec/requests/api/version_spec.rb

 require 'spec_helper'
 
 describe API::Version do
-  describe 'GET /version' do
+  shared_examples_for 'GET /version' do
     context 'when unauthenticated' do
       it 'returns authentication error' do
         get api('/version')
@@ -22,4 +22,20 @@ describe API::Version do
       end
     end
   end
+
+  context 'with graphql enabled' do
+    before do
+      stub_feature_flags(graphql: true)
+    end
+
+    include_examples 'GET /version'
+  end
+
+  context 'with graphql disabled' do
+    before do
+      stub_feature_flags(graphql: false)
+    end
+
+    include_examples 'GET /version'
+  end
 end

spec/support/helpers/graphql_helpers.rb

@@ -77,8 +77,9 @@ module GraphqlHelpers
   def query_graphql_field(name, attributes = {}, fields = nil)
     fields ||= all_graphql_fields_for(name.classify)
     attributes = attributes_to_graphql(attributes)
+    attributes = "(#{attributes})" if attributes.present?
     <<~QUERY
-      #{name}(#{attributes}) {
+      #{name}#{attributes} {
         #{fields}
       }
     QUERY