Expose runners status information in job api

app/helpers/ci_status_helper.rb

@@ -123,11 +123,6 @@ module CiStatusHelper
     render_status_with_link('pipeline', pipeline.status, path, tooltip_placement: tooltip_placement)
   end
 
-  def no_runners_for_project?(project)
-    project.runners.blank? &&
-      Ci::Runner.instance_type.blank?
-  end
-
   def render_status_with_link(type, status, path = nil, tooltip_placement: 'left', cssclass: '', container: 'body', icon_size: 16)
     klass = "ci-status-link ci-status-icon-#{status.dasherize} #{cssclass}"
     title = "#{type.titleize}: #{ci_label_for_status(status)}"

app/serializers/build_details_entity.rb

@@ -79,6 +79,20 @@ class BuildDetailsEntity < JobEntity
     expose :trigger_variables, as: :variables, using: TriggerVariableEntity
   end
 
+  expose :runners do
+    expose :online do |build|
+      build.any_runners_online?
+    end
+
+    expose :available do |build|
+      project.any_runners?
+    end
+
+    expose :settings_path, if: -> (*) { can_admin_build? } do |build|
+      project_runners_path(project)
+    end
+  end
+
   private
 
   def build_failed_issue_options
@@ -97,4 +111,8 @@ class BuildDetailsEntity < JobEntity
   def can_create_build_terminal?
     can?(current_user, :create_build_terminal, build) && build.has_terminal?
   end
+
+  def can_admin_build?
+    can?(request.current_user, :admin_build, project)
+  end
 end

app/views/projects/jobs/show.html.haml

@@ -10,7 +10,7 @@
       - unless @build.any_runners_online?
         .bs-callout.bs-callout-warning.js-build-stuck
           %p
-            - if no_runners_for_project?(@build.project)
+            - if @project.any_runners?
               This job is stuck, because the project doesn't have any runners online assigned to it.
             - elsif @build.tags.any?
               This job is stuck, because you don't have any active runners online with any of these tags assigned to them:

changelogs/unreleased/51273-expose-runners-for-build-in-job-api.yml

+---
+title: Expose project runners in job API
+merge_request: 21618
+author:
+type: other

spec/controllers/projects/jobs_controller_spec.rb

@@ -288,6 +288,55 @@ describe Projects::JobsController, :clean_gitlab_redis_shared_state do
           end
         end
       end
+
+      context 'when no runners are available' do
+        let(:runner) { create(:ci_runner, :instance, active: false) }
+        let(:job) { create(:ci_build, :pending, pipeline: pipeline, runner: runner) }
+
+        it 'exposes needed information' do
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(response).to match_response_schema('job/job_details')
+          expect(json_response['runners']['online']).to be false
+          expect(json_response['runners']['available']).to be false
+        end
+      end
+
+      context 'when no runner is online' do
+        let(:runner) { create(:ci_runner, :instance) }
+        let(:job) { create(:ci_build, :pending, pipeline: pipeline, runner: runner) }
+
+        it 'exposes needed information' do
+          expect(response).to have_gitlab_http_status(:ok)
+          expect(response).to match_response_schema('job/job_details')
+          expect(json_response['runners']['online']).to be false
+          expect(json_response['runners']['available']).to be true
+        end
+      end
+
+      context 'settings_path' do
+        context 'when user is developer' do
+          it 'settings_path is not available' do
+            expect(response).to have_gitlab_http_status(:ok)
+            expect(response).to match_response_schema('job/job_details')
+            expect(json_response['runners']).not_to have_key('settings_path')
+          end
+        end
+
+        context 'when user is maintainer' do
+          let(:user) { create(:user, :admin) }
+
+          before do
+            project.add_maintainer(user)
+            sign_in(user)
+          end
+
+          it 'settings_path is available' do
+            expect(response).to have_gitlab_http_status(:ok)
+            expect(response).to match_response_schema('job/job_details')
+            expect(json_response['runners']['settings_path']).to match(/runners/)
+          end
+        end
+      end
     end
 
     context 'when requesting JSON job is triggered' do

spec/fixtures/api/schemas/job/job_details.json

@@ -8,6 +8,7 @@
     "terminal_path": { "type": "string" },
     "trigger": { "$ref": "trigger.json" },
     "deployment_status": { "$ref": "deployment_status.json" },
-    "runner": { "$ref": "runner.json" }
+    "runner": { "$ref": "runner.json" },
+    "runners": { "type": "runners.json" }
   }
 }

spec/fixtures/api/schemas/job/runners.json

+{
+  "type": "object",
+  "required": [
+    "online",
+    "available"
+  ],
+  "properties": {
+    "online": { "type": "boolean" },
+    "available": { "type": "boolean" },
+    "settings_path": { "type": "string" }
+  },
+  "additionalProperties": false
+}