REST: Follow shared runners setting

When listing shared runners, follow the `Enable shared runners` setting:
https://docs.gitlab.com/ee/ci/runners/runners_scope.html#enable-shared-runners

Changelog: fixed

app/models/ci/runner.rb

@@ -152,11 +152,13 @@ module Ci
     }
 
     scope :owned_or_instance_wide, -> (project_id) do
+      project = project_id.respond_to?(:shared_runners) ? project_id : Project.find(project_id)
+
       from_union(
         [
           belonging_to_project(project_id),
           belonging_to_parent_group_of_project(project_id),
-          instance_type
+          project.shared_runners
         ],
         remove_duplicates: false
       )
@@ -173,7 +175,7 @@ module Ci
       from_union(
         [
           group_and_ancestor_runners,
-          instance_type
+          group.shared_runners
         ],
         remove_duplicates: false
       )

app/models/namespace.rb

@@ -492,6 +492,10 @@ class Namespace < ApplicationRecord
     end
   end
 
+  def shared_runners
+    @shared_runners ||= shared_runners_enabled ? Ci::Runner.instance_type : Ci::Runner.none
+  end
+
   def root?
     !has_parent?
   end

doc/api/runners.md

@@ -448,7 +448,7 @@ Example response:
 
 ## List project's runners
 
-List all runners available in the project, including from ancestor groups and any shared runners.
+List all runners available in the project, including from ancestor groups and [any allowed shared runners](../ci/runners/runners_scope.md#enable-shared-runners).
 
 ```plaintext
 GET /projects/:id/runners
@@ -566,7 +566,7 @@ curl --request DELETE --header "PRIVATE-TOKEN: <your_access_token>" "https://git
 
 ## List group's runners
 
-List all runners available in the group as well as its ancestor groups, including any shared runners.
+List all runners available in the group as well as its ancestor groups, including [any allowed shared runners](../ci/runners/runners_scope.md#enable-shared-runners).
 
 ```plaintext
 GET /groups/:id/runners

spec/models/ci/runner_spec.rb

@@ -280,8 +280,20 @@ RSpec.describe Ci::Runner do
     describe '.owned_or_instance_wide' do
       subject { described_class.owned_or_instance_wide(project.id) }
 
-      it 'returns a globally shared, a project specific and a group specific runner' do
-        is_expected.to contain_exactly(group_runner, project_runner, shared_runner)
+      context 'with instance runners sharing enabled' do
+        let(:shared_runners_enabled) { true }
+
+        it 'returns a globally shared, a project specific and a group specific runner' do
+          is_expected.to contain_exactly(group_runner, project_runner, shared_runner)
+        end
+      end
+
+      context 'with instance runners sharing disabled' do
+        let(:shared_runners_enabled) { false }
+
+        it 'returns a project specific and a group specific runner' do
+          is_expected.to contain_exactly(group_runner, project_runner)
+        end
       end
     end
 
@@ -293,8 +305,20 @@ RSpec.describe Ci::Runner do
         project_runner
       end
 
-      it 'returns a globally shared and a group specific runner' do
-        is_expected.to contain_exactly(group_runner, shared_runner)
+      context 'with instance runners sharing enabled' do
+        let(:shared_runners_enabled) { true }
+
+        it 'returns a globally shared and a group specific runner' do
+          is_expected.to contain_exactly(group_runner, shared_runner)
+        end
+      end
+
+      context 'with instance runners sharing disabled' do
+        let(:shared_runners_enabled) { false }
+
+        it 'returns a group specific runner' do
+          is_expected.to contain_exactly(group_runner)
+        end
       end
     end
   end