Ci Resouce Group status transition

This commit supports Ci Resource Group status transition

app/assets/stylesheets/framework/icons.scss

@@ -20,6 +20,7 @@
 }
 
 .ci-status-icon-pending,
+.ci-status-icon-waiting-for-resource,
 .ci-status-icon-failed-with-warnings,
 .ci-status-icon-success-with-warnings {
   svg {

app/assets/stylesheets/pages/pipelines.scss

@@ -795,6 +795,7 @@
   }
 
   &.ci-status-icon-pending,
+  &.ci-status-icon-waiting-for-resource,
   &.ci-status-icon-success-with-warnings {
     @include mini-pipeline-graph-color($white, $orange-100, $orange-200, $orange-500, $orange-600, $orange-700);
   }

app/assets/stylesheets/pages/status.scss

@@ -42,6 +42,7 @@
   }
 
   &.ci-pending,
+  &.ci-waiting-for-resource,
   &.ci-failed-with-warnings,
   &.ci-success-with-warnings {
     @include status-color($orange-100, $orange-500, $orange-700);

app/helpers/ci_status_helper.rb

@@ -62,6 +62,7 @@ module CiStatusHelper
     status.humanize
   end
 
+  # rubocop:disable Metrics/CyclomaticComplexity
   def ci_icon_for_status(status, size: 16)
     if detailed_status?(status)
       return sprite_icon(status.icon, size: size)
@@ -77,6 +78,8 @@ module CiStatusHelper
         'status_failed'
       when 'pending'
         'status_pending'
+      when 'waiting_for_resource'
+        'status_pending'
       when 'preparing'
         'status_preparing'
       when 'running'
@@ -97,6 +100,7 @@ module CiStatusHelper
 
     sprite_icon(icon_name, size: size)
   end
+  # rubocop:enable Metrics/CyclomaticComplexity
 
   def ci_icon_class_for_status(status)
     group = detailed_status?(status) ? status.group : status.dasherize

app/models/ci/build.rb

@@ -206,9 +206,25 @@ module Ci
 
     state_machine :status do
       event :enqueue do
+        transition [:created, :skipped, :manual, :scheduled] => :waiting_for_resource, if: :requires_resource?
         transition [:created, :skipped, :manual, :scheduled] => :preparing, if: :any_unmet_prerequisites?
       end
 
+      event :enqueue_scheduled do
+        transition scheduled: :waiting_for_resource, if: :requires_resource?
+        transition scheduled: :preparing, if: :any_unmet_prerequisites?
+        transition scheduled: :pending
+      end
+
+      event :enqueue_waiting_for_resource do
+        transition waiting_for_resource: :preparing, if: :any_unmet_prerequisites?
+        transition waiting_for_resource: :pending
+      end
+
+      event :enqueue_preparing do
+        transition preparing: :pending
+      end
+
       event :actionize do
         transition created: :manual
       end
@@ -221,14 +237,8 @@ module Ci
         transition scheduled: :manual
       end
 
-      event :enqueue_scheduled do
-        transition scheduled: :preparing, if: ->(build) do
-          build.scheduled_at&.past? && build.any_unmet_prerequisites?
-        end
-
-        transition scheduled: :pending, if: ->(build) do
-          build.scheduled_at&.past? && !build.any_unmet_prerequisites?
-        end
+      before_transition on: :enqueue_scheduled do |build|
+        build.scheduled_at.nil? || build.scheduled_at.past? # If false is returned, it stops the transition
       end
 
       before_transition scheduled: any do |build|
@@ -239,6 +249,27 @@ module Ci
         build.scheduled_at = build.options_scheduled_at
       end
 
+      before_transition any => :waiting_for_resource do |build|
+        build.waiting_for_resource_at = Time.now
+      end
+
+      before_transition on: :enqueue_waiting_for_resource do |build|
+        next unless build.requires_resource?
+
+        build.resource_group.assign_resource_to(build) # If false is returned, it stops the transition
+      end
+
+      after_transition any => :waiting_for_resource do |build|
+        build.run_after_commit do
+          Ci::ResourceGroups::AssignResourceFromResourceGroupWorker
+            .perform_async(build.resource_group_id)
+        end
+      end
+
+      before_transition on: :enqueue_preparing do |build|
+        build.any_unmet_prerequisites? # If false is returned, it stops the transition
+      end
+
       after_transition created: :scheduled do |build|
         build.run_after_commit do
           Ci::BuildScheduleWorker.perform_at(build.scheduled_at, build.id)
@@ -267,6 +298,16 @@ module Ci
         end
       end
 
+      after_transition any => ::Ci::Build.completed_statuses do |build|
+        next unless build.resource_group_id.present?
+        next unless build.resource_group.release_resource_from(build)
+
+        build.run_after_commit do
+          Ci::ResourceGroups::AssignResourceFromResourceGroupWorker
+            .perform_async(build.resource_group_id)
+        end
+      end
+
       after_transition any => [:success, :failed, :canceled] do |build|
         build.run_after_commit do
           BuildFinishedWorker.perform_async(id)
@@ -439,6 +480,11 @@ module Ci
       end
     end
 
+    def requires_resource?
+      Feature.enabled?(:ci_resource_group, project) &&
+        self.resource_group_id.present?
+    end
+
     def has_environment?
       environment.present?
     end

app/models/ci/pipeline.rb

@@ -95,10 +95,14 @@ module Ci
 
     state_machine :status, initial: :created do
       event :enqueue do
-        transition [:created, :preparing, :skipped, :scheduled] => :pending
+        transition [:created, :waiting_for_resource, :preparing, :skipped, :scheduled] => :pending
         transition [:success, :failed, :canceled] => :running
       end
 
+      event :request_resource do
+        transition any - [:waiting_for_resource] => :waiting_for_resource
+      end
+
       event :prepare do
         transition any - [:preparing] => :preparing
       end
@@ -135,7 +139,7 @@ module Ci
       # Do not add any operations to this state_machine
       # Create a separate worker for each new operation
 
-      before_transition [:created, :preparing, :pending] => :running do |pipeline|
+      before_transition [:created, :waiting_for_resource, :preparing, :pending] => :running do |pipeline|
         pipeline.started_at = Time.now
       end
 
@@ -158,7 +162,7 @@ module Ci
         end
       end
 
-      after_transition [:created, :preparing, :pending] => :running do |pipeline|
+      after_transition [:created, :waiting_for_resource, :preparing, :pending] => :running do |pipeline|
         pipeline.run_after_commit { PipelineMetricsWorker.perform_async(pipeline.id) }
       end
 
@@ -166,7 +170,7 @@ module Ci
         pipeline.run_after_commit { PipelineMetricsWorker.perform_async(pipeline.id) }
       end
 
-      after_transition [:created, :preparing, :pending, :running] => :success do |pipeline|
+      after_transition [:created, :waiting_for_resource, :preparing, :pending, :running] => :success do |pipeline|
         pipeline.run_after_commit { PipelineSuccessWorker.perform_async(pipeline.id) }
       end
 
@@ -317,7 +321,7 @@ module Ci
     end
 
     def self.bridgeable_statuses
-      ::Ci::Pipeline::AVAILABLE_STATUSES - %w[created preparing pending]
+      ::Ci::Pipeline::AVAILABLE_STATUSES - %w[created waiting_for_resource preparing pending]
     end
 
     def stages_count
@@ -576,6 +580,7 @@ module Ci
         new_status = latest_builds_status.to_s
         case new_status
         when 'created' then nil
+        when 'waiting_for_resource' then request_resource
         when 'preparing' then prepare
         when 'pending' then enqueue
         when 'running' then run

app/models/ci/stage.rb

@@ -39,10 +39,14 @@ module Ci
 
     state_machine :status, initial: :created do
       event :enqueue do
-        transition [:created, :preparing] => :pending
+        transition [:created, :waiting_for_resource, :preparing] => :pending
         transition [:success, :failed, :canceled, :skipped] => :running
       end
 
+      event :request_resource do
+        transition any - [:waiting_for_resource] => :waiting_for_resource
+      end
+
       event :prepare do
         transition any - [:preparing] => :preparing
       end
@@ -81,6 +85,7 @@ module Ci
         new_status = latest_stage_status.to_s
         case new_status
         when 'created' then nil
+        when 'waiting_for_resource' then request_resource
         when 'preparing' then prepare
         when 'pending' then enqueue
         when 'running' then run

app/models/commit_status.rb

@@ -96,7 +96,7 @@ class CommitStatus < ApplicationRecord
       # A CommitStatus will never have prerequisites, but this event
       # is shared by Ci::Build, which cannot progress unless prerequisites
       # are satisfied.
-      transition [:created, :preparing, :skipped, :manual, :scheduled] => :pending, unless: :any_unmet_prerequisites?
+      transition [:created, :skipped, :manual, :scheduled] => :pending, if: :all_met_to_become_pending?
     end
 
     event :run do
@@ -104,22 +104,22 @@ class CommitStatus < ApplicationRecord
     end
 
     event :skip do
-      transition [:created, :preparing, :pending] => :skipped
+      transition [:created, :waiting_for_resource, :preparing, :pending] => :skipped
     end
 
     event :drop do
-      transition [:created, :preparing, :pending, :running, :scheduled] => :failed
+      transition [:created, :waiting_for_resource, :preparing, :pending, :running, :scheduled] => :failed
     end
 
     event :success do
-      transition [:created, :preparing, :pending, :running] => :success
+      transition [:created, :waiting_for_resource, :preparing, :pending, :running] => :success
     end
 
     event :cancel do
-      transition [:created, :preparing, :pending, :running, :manual, :scheduled] => :canceled
+      transition [:created, :waiting_for_resource, :preparing, :pending, :running, :manual, :scheduled] => :canceled
     end
 
-    before_transition [:created, :preparing, :skipped, :manual, :scheduled] => :pending do |commit_status|
+    before_transition [:created, :waiting_for_resource, :preparing, :skipped, :manual, :scheduled] => :pending do |commit_status|
       commit_status.queued_at = Time.now
     end
 
@@ -218,10 +218,18 @@ class CommitStatus < ApplicationRecord
     false
   end
 
+  def all_met_to_become_pending?
+    !any_unmet_prerequisites? && !requires_resource?
+  end
+
   def any_unmet_prerequisites?
     false
   end
 
+  def requires_resource?
+    false
+  end
+
   def auto_canceled?
     canceled? && auto_canceled_by_id?
   end

app/models/concerns/has_status.rb

@@ -5,16 +5,16 @@ module HasStatus
 
   DEFAULT_STATUS = 'created'
   BLOCKED_STATUS = %w[manual scheduled].freeze
-  AVAILABLE_STATUSES = %w[created preparing pending running success failed canceled skipped manual scheduled].freeze
+  AVAILABLE_STATUSES = %w[created waiting_for_resource preparing pending running success failed canceled skipped manual scheduled].freeze
   STARTED_STATUSES = %w[running success failed skipped manual scheduled].freeze
   ACTIVE_STATUSES = %w[preparing pending running].freeze
   COMPLETED_STATUSES = %w[success failed canceled skipped].freeze
-  ORDERED_STATUSES = %w[failed preparing pending running manual scheduled canceled success skipped created].freeze
+  ORDERED_STATUSES = %w[failed preparing pending running waiting_for_resource manual scheduled canceled success skipped created].freeze
   PASSED_WITH_WARNINGS_STATUSES = %w[failed canceled].to_set.freeze
   EXCLUDE_IGNORED_STATUSES = %w[manual failed canceled].to_set.freeze
   STATUSES_ENUM = { created: 0, pending: 1, running: 2, success: 3,
                     failed: 4, canceled: 5, skipped: 6, manual: 7,
-                    scheduled: 8, preparing: 9 }.freeze
+                    scheduled: 8, preparing: 9, waiting_for_resource: 10 }.freeze
 
   UnknownStatusError = Class.new(StandardError)
 
@@ -29,6 +29,7 @@ module HasStatus
       manual = scope_relevant.manual.select('count(*)').to_sql
       scheduled = scope_relevant.scheduled.select('count(*)').to_sql
       preparing = scope_relevant.preparing.select('count(*)').to_sql
+      waiting_for_resource = scope_relevant.waiting_for_resource.select('count(*)').to_sql
       pending = scope_relevant.pending.select('count(*)').to_sql
       running = scope_relevant.running.select('count(*)').to_sql
       skipped = scope_relevant.skipped.select('count(*)').to_sql
@@ -46,6 +47,7 @@ module HasStatus
           WHEN (#{builds})=(#{success})+(#{skipped})+(#{canceled}) THEN 'canceled'
           WHEN (#{builds})=(#{created})+(#{skipped})+(#{pending}) THEN 'pending'
           WHEN (#{running})+(#{pending})>0 THEN 'running'
+          WHEN (#{waiting_for_resource})>0 THEN 'waiting_for_resource'
           WHEN (#{manual})>0 THEN 'manual'
           WHEN (#{scheduled})>0 THEN 'scheduled'
           WHEN (#{preparing})>0 THEN 'preparing'
@@ -95,6 +97,7 @@ module HasStatus
 
     state_machine :status, initial: :created do
       state :created, value: 'created'
+      state :waiting_for_resource, value: 'waiting_for_resource'
       state :preparing, value: 'preparing'
       state :pending, value: 'pending'
       state :running, value: 'running'
@@ -107,6 +110,7 @@ module HasStatus
     end
 
     scope :created, -> { with_status(:created) }
+    scope :waiting_for_resource, -> { with_status(:waiting_for_resource) }
     scope :preparing, -> { with_status(:preparing) }
     scope :relevant, -> { without_status(:created) }
     scope :running, -> { with_status(:running) }
@@ -117,8 +121,8 @@ module HasStatus
     scope :skipped, -> { with_status(:skipped) }
     scope :manual, -> { with_status(:manual) }
     scope :scheduled, -> { with_status(:scheduled) }
-    scope :alive, -> { with_status(:created, :preparing, :pending, :running) }
-    scope :alive_or_scheduled, -> { with_status(:created, :preparing, :pending, :running, :scheduled) }
+    scope :alive, -> { with_status(:created, :waiting_for_resource, :preparing, :pending, :running) }
+    scope :alive_or_scheduled, -> { with_status(:created, :waiting_for_resource, :preparing, :pending, :running, :scheduled) }
     scope :created_or_pending, -> { with_status(:created, :pending) }
     scope :running_or_pending, -> { with_status(:running, :pending) }
     scope :finished, -> { with_status(:success, :failed, :canceled) }
@@ -126,7 +130,7 @@ module HasStatus
     scope :incomplete, -> { without_statuses(completed_statuses) }
 
     scope :cancelable, -> do
-      where(status: [:running, :preparing, :pending, :created, :scheduled])
+      where(status: [:running, :waiting_for_resource, :preparing, :pending, :created, :scheduled])
     end
 
     scope :without_statuses, -> (names) do

app/services/ci/prepare_build_service.rb

@@ -11,7 +11,7 @@ module Ci
     def execute
       prerequisites.each(&:complete!)
 
-      build.enqueue!
+      build.enqueue_preparing!
     rescue => e
       Gitlab::ErrorTracking.track_exception(e, build_id: build.id)
 

app/services/ci/resource_groups/assign_resource_from_resource_group_service.rb

+# frozen_string_literal: true
+
+module Ci
+  module ResourceGroups
+    class AssignResourceFromResourceGroupService < ::BaseService
+      # rubocop: disable CodeReuse/ActiveRecord
+      def execute(resource_group)
+        free_resources = resource_group.resources.free.count
+
+        resource_group.builds.waiting_for_resource.take(free_resources).each do |build|
+          build.enqueue_waiting_for_resource
+        end
+      end
+      # rubocop: enable CodeReuse/ActiveRecord
+    end
+  end
+end

app/workers/all_queues.yml

@@ -103,6 +103,7 @@
 - pipeline_processing:stage_update
 - pipeline_processing:update_head_pipeline_for_merge_request
 - pipeline_processing:ci_build_schedule
+- pipeline_processing:ci_resource_groups_assign_resource_from_resource_group
 
 - deployment:deployments_success
 - deployment:deployments_finished

app/workers/ci/resource_groups/assign_resource_from_resource_group_worker.rb

+# frozen_string_literal: true
+
+module Ci
+  module ResourceGroups
+    class AssignResourceFromResourceGroupWorker
+      include ApplicationWorker
+      include PipelineQueue
+
+      queue_namespace :pipeline_processing
+      feature_category :continuous_delivery
+
+      def perform(resource_group_id)
+        ::Ci::ResourceGroup.find_by_id(resource_group_id).try do |resource_group|
+          Ci::ResourceGroups::AssignResourceFromResourceGroupService.new(resource_group.project, nil)
+            .execute(resource_group)
+        end
+      end
+    end
+  end
+end

doc/api/graphql/reference/gitlab_schema.graphql

@@ -4443,7 +4443,8 @@ type Pipeline {
   startedAt: Time
 
   """
-  Status of the pipeline (CREATED, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED)
+  Status of the pipeline (CREATED, WAITING_FOR_RESOURCE, PREPARING, PENDING,
+  RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED)
   """
   status: PipelineStatusEnum!
 
@@ -4521,6 +4522,7 @@ enum PipelineStatusEnum {
   SCHEDULED
   SKIPPED
   SUCCESS
+  WAITING_FOR_RESOURCE
 }
 
 type Project {

doc/api/graphql/reference/gitlab_schema.json

@@ -12203,7 +12203,7 @@
             },
             {
               "name": "status",
-              "description": "Status of the pipeline (CREATED, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED)",
+              "description": "Status of the pipeline (CREATED, WAITING_FOR_RESOURCE, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED)",
               "args": [
 
               ],
@@ -12344,6 +12344,12 @@
               "isDeprecated": false,
               "deprecationReason": null
             },
+            {
+              "name": "WAITING_FOR_RESOURCE",
+              "description": null,
+              "isDeprecated": false,
+              "deprecationReason": null
+            },
             {
               "name": "PREPARING",
               "description": null,

doc/api/graphql/reference/index.md

@@ -635,7 +635,7 @@ The API can be explored interactively using the [GraphiQL IDE](../index.md#graph
 | `iid` | String! | Internal ID of the pipeline |
 | `sha` | String! | SHA of the pipeline's commit |
 | `beforeSha` | String | Base SHA of the source branch |
-| `status` | PipelineStatusEnum! | Status of the pipeline (CREATED, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED) |
+| `status` | PipelineStatusEnum! | Status of the pipeline (CREATED, WAITING_FOR_RESOURCE, PREPARING, PENDING, RUNNING, FAILED, SUCCESS, CANCELED, SKIPPED, MANUAL, SCHEDULED) |
 | `detailedStatus` | DetailedStatus! | Detailed status of the pipeline |
 | `duration` | Int | Duration of the pipeline in seconds |
 | `coverage` | Float | Coverage percentage |

lib/gitlab/ci/status/build/factory.rb

@@ -11,6 +11,7 @@ module Gitlab
               Status::Build::Manual,
               Status::Build::Canceled,
               Status::Build::Created,
+              Status::Build::WaitingForResource,
               Status::Build::Preparing,
               Status::Build::Pending,
               Status::Build::Skipped],

lib/gitlab/ci/status/build/waiting_for_resource.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Status
+      module Build
+        class WaitingForResource < Status::Extended
+          ##
+          # TODO: image is shared with 'pending'
+          # until we get a dedicated one
+          #
+          def illustration
+            {
+              image: 'illustrations/pending_job_empty.svg',
+              size: 'svg-430',
+              title: _('This job is waiting for resource: ') + subject.resource_group.key
+            }
+          end
+
+          def self.matches?(build, _)
+            build.waiting_for_resource?
+          end
+        end
+      end
+    end
+  end
+end

lib/gitlab/ci/status/composite.rb

@@ -25,6 +25,8 @@ module Gitlab
         # 2. In other cases we assume that status is of that type
         #    based on what statuses are no longer valid based on the
         #    data set that we have
+        # rubocop: disable Metrics/CyclomaticComplexity
+        # rubocop: disable Metrics/PerceivedComplexity
         def status
           return if none?
 
@@ -43,6 +45,8 @@ module Gitlab
               'pending'
             elsif any_of?(:running, :pending)
               'running'
+            elsif any_of?(:waiting_for_resource)
+              'waiting_for_resource'
             elsif any_of?(:manual)
               'manual'
             elsif any_of?(:scheduled)
@@ -56,6 +60,8 @@ module Gitlab
             end
           end
         end
+        # rubocop: enable Metrics/CyclomaticComplexity
+        # rubocop: enable Metrics/PerceivedComplexity
 
         def warnings?
           @status_set.include?(:success_with_warnings)

lib/gitlab/ci/status/factory.rb

@@ -20,7 +20,7 @@ module Gitlab
 
         def core_status
           Gitlab::Ci::Status
-            .const_get(@status.capitalize, false)
+            .const_get(@status.to_s.camelize, false)
             .new(@subject, @user)
             .extend(self.class.common_helpers)
         end

lib/gitlab/ci/status/waiting_for_resource.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Status
+      class WaitingForResource < Status::Core
+        def text
+          s_('CiStatusText|waiting')
+        end
+
+        def label
+          s_('CiStatusLabel|waiting for resource')
+        end
+
+        def icon
+          'status_pending'
+        end
+
+        def favicon
+          'favicon_pending'
+        end
+
+        def group
+          'waiting-for-resource'
+        end
+      end
+    end
+  end
+end

locale/gitlab.pot

@@ -3358,6 +3358,9 @@ msgstr ""
 msgid "CiStatusLabel|waiting for manual action"
 msgstr ""
 
+msgid "CiStatusLabel|waiting for resource"
+msgstr ""
+
 msgid "CiStatusText|blocked"
 msgstr ""
 
@@ -3388,6 +3391,9 @@ msgstr ""
 msgid "CiStatusText|skipped"
 msgstr ""
 
+msgid "CiStatusText|waiting"
+msgstr ""
+
 msgid "CiStatus|running"
 msgstr ""
 
@@ -18505,6 +18511,9 @@ msgstr ""
 msgid "This job is stuck because you don't have any active runners that can run this job."
 msgstr ""
 
+msgid "This job is waiting for resource: "
+msgstr ""
+
 msgid "This job requires a manual action"
 msgstr ""
 

spec/factories/ci/builds.rb

@@ -77,6 +77,10 @@ FactoryBot.define do
       status { 'created' }
     end
 
+    trait :waiting_for_resource do
+      status { 'waiting_for_resource' }
+    end
+
     trait :preparing do
       status { 'preparing' }
     end

spec/factories/commit_statuses.rb

@@ -35,6 +35,10 @@ FactoryBot.define do
       status { 'pending' }
     end
 
+    trait :waiting_for_resource do
+      status { 'waiting_for_resource' }
+    end
+
     trait :preparing do
       status { 'preparing' }
     end

spec/features/projects/pipelines/pipeline_spec.rb

@@ -606,6 +606,117 @@ describe 'Pipeline', :js do
     end
   end
 
+  context 'when build requires resource', :sidekiq_inline do
+    let_it_be(:project) { create(:project, :repository) }
+    let(:pipeline) { create(:ci_pipeline, project: project) }
+    let(:resource_group) { create(:ci_resource_group, project: project) }
+
+    let!(:test_job) do
+      create(:ci_build, :pending, stage: 'test', name: 'test',
+        stage_idx: 1, pipeline: pipeline, project: project)
+    end
+
+    let!(:deploy_job) do
+      create(:ci_build, :created, stage: 'deploy', name: 'deploy',
+        stage_idx: 2, pipeline: pipeline, project: project, resource_group: resource_group)
+    end
+
+    describe 'GET /:project/pipelines/:id' do
+      subject { visit project_pipeline_path(project, pipeline) }
+
+      it 'shows deploy job as created' do
+        subject
+
+        within('.pipeline-header-container') do
+          expect(page).to have_content('pending')
+        end
+
+        within('.pipeline-graph') do
+          within '.stage-column:nth-child(1)' do
+            expect(page).to have_content('test')
+            expect(page).to have_css('.ci-status-icon-pending')
+          end
+
+          within '.stage-column:nth-child(2)' do
+            expect(page).to have_content('deploy')
+            expect(page).to have_css('.ci-status-icon-created')
+          end
+        end
+      end
+
+      context 'when test job succeeded' do
+        before do
+          test_job.success!
+        end
+
+        it 'shows deploy job as pending' do
+          subject
+
+          within('.pipeline-header-container') do
+            expect(page).to have_content('running')
+          end
+
+          within('.pipeline-graph') do
+            within '.stage-column:nth-child(1)' do
+              expect(page).to have_content('test')
+              expect(page).to have_css('.ci-status-icon-success')
+            end
+
+            within '.stage-column:nth-child(2)' do
+              expect(page).to have_content('deploy')
+              expect(page).to have_css('.ci-status-icon-pending')
+            end
+          end
+        end
+      end
+
+      context 'when test job succeeded but there are no available resources' do
+        let(:another_job) { create(:ci_build, :running, project: project, resource_group: resource_group) }
+
+        before do
+          resource_group.assign_resource_to(another_job)
+          test_job.success!
+        end
+
+        it 'shows deploy job as waiting for resource' do
+          subject
+
+          within('.pipeline-header-container') do
+            expect(page).to have_content('waiting')
+          end
+
+          within('.pipeline-graph') do
+            within '.stage-column:nth-child(2)' do
+              expect(page).to have_content('deploy')
+              expect(page).to have_css('.ci-status-icon-waiting-for-resource')
+            end
+          end
+        end
+
+        context 'when resource is released from another job' do
+          before do
+            another_job.success!
+          end
+
+          it 'shows deploy job as pending' do
+            subject
+
+            within('.pipeline-header-container') do
+              expect(page).to have_content('running')
+            end
+
+            within('.pipeline-graph') do
+              within '.stage-column:nth-child(2)' do
+                expect(page).to have_content('deploy')
+                expect(page).to have_css('.ci-status-icon-pending')
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+
   describe 'GET /:project/pipelines/:id/builds' do
     include_context 'pipeline builds'
 

spec/lib/gitlab/ci/status/external/factory_spec.rb

@@ -22,7 +22,7 @@ describe Gitlab::Ci::Status::External::Factory do
         end
 
         let(:expected_status) do
-          Gitlab::Ci::Status.const_get(simple_status.capitalize, false)
+          Gitlab::Ci::Status.const_get(simple_status.to_s.camelize, false)
         end
 
         it "fabricates a core status #{simple_status}" do

spec/lib/gitlab/ci/status/factory_spec.rb

@@ -13,7 +13,7 @@ describe Gitlab::Ci::Status::Factory do
         let(:resource) { double('resource', status: simple_status) }
 
         let(:expected_status) do
-          Gitlab::Ci::Status.const_get(simple_status.capitalize, false)
+          Gitlab::Ci::Status.const_get(simple_status.to_s.camelize, false)
         end
 
         it "fabricates a core status #{simple_status}" do

spec/lib/gitlab/ci/status/pipeline/factory_spec.rb

@@ -18,7 +18,7 @@ describe Gitlab::Ci::Status::Pipeline::Factory do
         let(:pipeline) { create(:ci_pipeline, status: simple_status) }
 
         let(:expected_status) do
-          Gitlab::Ci::Status.const_get(simple_status.capitalize, false)
+          Gitlab::Ci::Status.const_get(simple_status.camelize, false)
         end
 
         it "matches correct core status for #{simple_status}" do

spec/lib/gitlab/ci/status/stage/factory_spec.rb

@@ -34,7 +34,7 @@ describe Gitlab::Ci::Status::Stage::Factory do
 
         it "fabricates a core status #{core_status}" do
           expect(status).to be_a(
-            Gitlab::Ci::Status.const_get(core_status.capitalize, false))
+            Gitlab::Ci::Status.const_get(core_status.camelize, false))
         end
 
         it 'extends core status with common stage methods' do

spec/lib/gitlab/ci/status/waiting_for_resource_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Gitlab::Ci::Status::WaitingForResource do
+  subject do
+    described_class.new(double('subject'), double('user'))
+  end
+
+  describe '#text' do
+    it { expect(subject.text).to eq 'waiting' }
+  end
+
+  describe '#label' do
+    it { expect(subject.label).to eq 'waiting for resource' }
+  end
+
+  describe '#icon' do
+    it { expect(subject.icon).to eq 'status_pending' }
+  end
+
+  describe '#favicon' do
+    it { expect(subject.favicon).to eq 'favicon_pending' }
+  end
+
+  describe '#group' do
+    it { expect(subject.group).to eq 'waiting-for-resource' }
+  end
+end

spec/models/ci/build_spec.rb

@@ -1119,6 +1119,60 @@ describe Ci::Build do
     end
   end
 
+  describe 'state transition with resource group' do
+    let(:resource_group) { create(:ci_resource_group, project: project) }
+
+    context 'when build status is created' do
+      let(:build) { create(:ci_build, :created, project: project, resource_group: resource_group) }
+
+      it 'is waiting for resource when build is enqueued' do
+        expect(Ci::ResourceGroups::AssignResourceFromResourceGroupWorker).to receive(:perform_async).with(resource_group.id)
+
+        expect { build.enqueue! }.to change { build.status }.from('created').to('waiting_for_resource')
+
+        expect(build.waiting_for_resource_at).not_to be_nil
+      end
+
+      context 'when build is waiting for resource' do
+        before do
+          build.update_column(:status, 'waiting_for_resource')
+        end
+
+        it 'is enqueued when build requests resource' do
+          expect { build.enqueue_waiting_for_resource! }.to change { build.status }.from('waiting_for_resource').to('pending')
+        end
+
+        it 'releases a resource when build finished' do
+          expect(build.resource_group).to receive(:release_resource_from).with(build).and_call_original
+          expect(Ci::ResourceGroups::AssignResourceFromResourceGroupWorker).to receive(:perform_async).with(build.resource_group_id)
+
+          build.enqueue_waiting_for_resource!
+          build.success!
+        end
+
+        context 'when build has prerequisites' do
+          before do
+            allow(build).to receive(:any_unmet_prerequisites?) { true }
+          end
+
+          it 'is preparing when build is enqueued' do
+            expect { build.enqueue_waiting_for_resource! }.to change { build.status }.from('waiting_for_resource').to('preparing')
+          end
+        end
+
+        context 'when there are no available resources' do
+          before do
+            resource_group.assign_resource_to(create(:ci_build))
+          end
+
+          it 'stays as waiting for resource when build requests resource' do
+            expect { build.enqueue_waiting_for_resource }.not_to change { build.status }
+          end
+        end
+      end
+    end
+  end
+
   describe '#on_stop' do
     subject { build.on_stop }
 

spec/models/ci/pipeline_spec.rb

@@ -1749,7 +1749,7 @@ describe Ci::Pipeline, :mailer do
     subject { described_class.bridgeable_statuses }
 
     it { is_expected.to be_an(Array) }
-    it { is_expected.not_to include('created', 'preparing', 'pending') }
+    it { is_expected.not_to include('created', 'waiting_for_resource', 'preparing', 'pending') }
   end
 
   describe '#status', :sidekiq_might_not_need_inline do
@@ -1759,6 +1759,17 @@ describe Ci::Pipeline, :mailer do
 
     subject { pipeline.reload.status }
 
+    context 'on waiting for resource' do
+      before do
+        allow(build).to receive(:requires_resource?) { true }
+        allow(Ci::ResourceGroups::AssignResourceFromResourceGroupWorker).to receive(:perform_async)
+
+        build.enqueue
+      end
+
+      it { is_expected.to eq('waiting_for_resource') }
+    end
+
     context 'on prepare' do
       before do
         # Prevent skipping directly to 'pending'

spec/models/ci/stage_spec.rb

@@ -105,6 +105,18 @@ describe Ci::Stage, :models do
       end
     end
 
+    context 'when build is waiting for resource' do
+      before do
+        create(:ci_build, :waiting_for_resource, stage_id: stage.id)
+      end
+
+      it 'updates status to waiting for resource' do
+        expect { stage.update_status }
+          .to change { stage.reload.status }
+          .to 'waiting_for_resource'
+      end
+    end
+
     context 'when stage is skipped because is empty' do
       it 'updates status to skipped' do
         expect { stage.update_status }

spec/models/commit_status_spec.rb

@@ -634,6 +634,30 @@ describe CommitStatus do
     end
   end
 
+  describe '#all_met_to_become_pending?' do
+    subject { commit_status.all_met_to_become_pending? }
+
+    let(:commit_status) { create(:commit_status) }
+
+    it { is_expected.to eq(true) }
+
+    context 'when build requires a resource' do
+      before do
+        allow(commit_status).to receive(:requires_resource?) { true }
+      end
+
+      it { is_expected.to eq(false) }
+    end
+
+    context 'when build has a prerequisite' do
+      before do
+        allow(commit_status).to receive(:any_unmet_prerequisites?) { true }
+      end
+
+      it { is_expected.to eq(false) }
+    end
+  end
+
   describe '#enqueue' do
     let!(:current_time) { Time.new(2018, 4, 5, 14, 0, 0) }
 
@@ -654,12 +678,6 @@ describe CommitStatus do
       it_behaves_like 'commit status enqueued'
     end
 
-    context 'when initial state is :preparing' do
-      let(:commit_status) { create(:commit_status, :preparing) }
-
-      it_behaves_like 'commit status enqueued'
-    end
-
     context 'when initial state is :skipped' do
       let(:commit_status) { create(:commit_status, :skipped) }
 

spec/models/concerns/has_status_spec.rb

@@ -39,6 +39,22 @@ describe HasStatus do
         it { is_expected.to eq 'running' }
       end
 
+      context 'all waiting for resource' do
+        let!(:statuses) do
+          [create(type, status: :waiting_for_resource), create(type, status: :waiting_for_resource)]
+        end
+
+        it { is_expected.to eq 'waiting_for_resource' }
+      end
+
+      context 'at least one waiting for resource' do
+        let!(:statuses) do
+          [create(type, status: :success), create(type, status: :waiting_for_resource)]
+        end
+
+        it { is_expected.to eq 'waiting_for_resource' }
+      end
+
       context 'all preparing' do
         let!(:statuses) do
           [create(type, status: :preparing), create(type, status: :preparing)]
@@ -219,7 +235,7 @@ describe HasStatus do
       end
     end
 
-    %i[created preparing running pending success
+    %i[created waiting_for_resource preparing running pending success
        failed canceled skipped].each do |status|
       it_behaves_like 'having a job', status
     end
@@ -265,7 +281,7 @@ describe HasStatus do
     describe '.alive' do
       subject { CommitStatus.alive }
 
-      %i[running pending preparing created].each do |status|
+      %i[running pending waiting_for_resource preparing created].each do |status|
         it_behaves_like 'containing the job', status
       end
 
@@ -277,7 +293,7 @@ describe HasStatus do
     describe '.alive_or_scheduled' do
       subject { CommitStatus.alive_or_scheduled }
 
-      %i[running pending preparing created scheduled].each do |status|
+      %i[running pending waiting_for_resource preparing created scheduled].each do |status|
         it_behaves_like 'containing the job', status
       end
 
@@ -313,7 +329,7 @@ describe HasStatus do
     describe '.cancelable' do
       subject { CommitStatus.cancelable }
 
-      %i[running pending preparing created scheduled].each do |status|
+      %i[running pending waiting_for_resource preparing created scheduled].each do |status|
         it_behaves_like 'containing the job', status
       end
 

spec/services/ci/prepare_build_service_spec.rb

@@ -14,7 +14,7 @@ describe Ci::PrepareBuildService do
 
     shared_examples 'build enqueueing' do
       it 'enqueues the build' do
-        expect(build).to receive(:enqueue).once
+        expect(build).to receive(:enqueue_preparing).once
 
         subject
       end
@@ -34,7 +34,7 @@ describe Ci::PrepareBuildService do
 
       context 'prerequisites fail to complete' do
         before do
-          allow(build).to receive(:enqueue).and_return(false)
+          allow(build).to receive(:enqueue_preparing).and_return(false)
         end
 
         it 'drops the build' do

spec/services/ci/process_pipeline_service_spec.rb

@@ -261,12 +261,16 @@ describe Ci::ProcessPipelineService, '#execute' do
 
           expect(builds_names_and_statuses).to eq({ 'build': 'success', 'rollout10%': 'scheduled' })
 
+          Timecop.travel 2.minutes.from_now do
             enqueue_scheduled('rollout10%')
+          end
           succeed_pending
 
           expect(builds_names_and_statuses).to eq({ 'build': 'success', 'rollout10%': 'success', 'rollout100%': 'scheduled' })
 
+          Timecop.travel 2.minutes.from_now do
             enqueue_scheduled('rollout100%')
+          end
           succeed_pending
 
           expect(builds_names_and_statuses).to eq({ 'build': 'success', 'rollout10%': 'success', 'rollout100%': 'success', 'cleanup': 'pending' })
@@ -328,7 +332,9 @@ describe Ci::ProcessPipelineService, '#execute' do
 
           expect(builds_names_and_statuses).to eq({ 'build': 'success', 'rollout10%': 'scheduled' })
 
+          Timecop.travel 2.minutes.from_now do
             enqueue_scheduled('rollout10%')
+          end
           fail_running_or_pending
 
           expect(builds_names_and_statuses).to eq({ 'build': 'success', 'rollout10%': 'failed' })
@@ -394,7 +400,9 @@ describe Ci::ProcessPipelineService, '#execute' do
         expect(process_pipeline).to be_truthy
         expect(builds_names_and_statuses).to eq({ 'delayed1': 'scheduled', 'delayed2': 'scheduled' })
 
+        Timecop.travel 2.minutes.from_now do
           enqueue_scheduled('delayed1')
+        end
 
         expect(builds_names_and_statuses).to eq({ 'delayed1': 'pending', 'delayed2': 'scheduled' })
         expect(pipeline.reload.status).to eq 'running'
@@ -413,7 +421,9 @@ describe Ci::ProcessPipelineService, '#execute' do
         expect(process_pipeline).to be_truthy
         expect(builds_names_and_statuses).to eq({ 'delayed': 'scheduled' })
 
+        Timecop.travel 2.minutes.from_now do
           enqueue_scheduled('delayed')
+        end
         fail_running_or_pending
 
         expect(builds_names_and_statuses).to eq({ 'delayed': 'failed', 'job': 'pending' })
@@ -906,7 +916,7 @@ describe Ci::ProcessPipelineService, '#execute' do
   end
 
   def enqueue_scheduled(name)
-    builds.scheduled.find_by(name: name).enqueue
+    builds.scheduled.find_by(name: name).enqueue_scheduled
   end
 
   def retry_build(name)

spec/services/ci/resource_groups/assign_resource_from_resource_group_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Ci::ResourceGroups::AssignResourceFromResourceGroupService do
+  let_it_be(:project) { create(:project) }
+  let_it_be(:user) { create(:user) }
+  let(:service) { described_class.new(project, user) }
+
+  describe '#execute' do
+    subject { service.execute(resource_group) }
+
+    let(:resource_group) { create(:ci_resource_group, project: project) }
+    let!(:build) { create(:ci_build, :waiting_for_resource, project: project, user: user, resource_group: resource_group) }
+
+    context 'when there is an available resource' do
+      it 'requests resource' do
+        subject
+
+        expect(build.reload).to be_pending
+        expect(build.resource).to be_present
+      end
+
+      context 'when failed to request resource' do
+        before do
+          allow_next_instance_of(Ci::Build) do |build|
+            allow(build).to receive(:enqueue_waiting_for_resource) { false }
+          end
+        end
+
+        it 'has a build waiting for resource' do
+          subject
+
+          expect(build).to be_waiting_for_resource
+        end
+      end
+
+      context 'when the build has already retained a resource' do
+        before do
+          resource_group.assign_resource_to(build)
+          build.update_column(:status, :pending)
+        end
+
+        it 'has a pending build' do
+          subject
+
+          expect(build).to be_pending
+        end
+      end
+    end
+
+    context 'when there are no available resources' do
+      before do
+        resource_group.assign_resource_to(create(:ci_build))
+      end
+
+      it 'does not request resource' do
+        expect_any_instance_of(Ci::Build).not_to receive(:enqueue_waiting_for_resource)
+
+        subject
+      end
+    end
+  end
+end

spec/services/ci/run_scheduled_build_service_spec.rb

@@ -26,6 +26,18 @@ describe Ci::RunScheduledBuildService do
 
           expect(build).to be_pending
         end
+
+        context 'when build requires resource' do
+          let(:resource_group) { create(:ci_resource_group, project: project) }
+
+          before do
+            build.update!(resource_group: resource_group)
+          end
+
+          it 'transits to waiting for resource status' do
+            expect { subject }.to change { build.status }.from('scheduled').to('waiting_for_resource')
+          end
+        end
       end
 
       context 'when scheduled_at is not expired' do

spec/workers/ci/resource_groups/assign_resource_from_resource_group_worker_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Ci::ResourceGroups::AssignResourceFromResourceGroupWorker do
+  let(:worker) { described_class.new }
+
+  describe '#perform' do
+    subject { worker.perform(resource_group_id) }
+
+    context 'when resource group exists' do
+      let(:resource_group) { create(:ci_resource_group) }
+      let(:resource_group_id) { resource_group.id }
+
+      it 'executes AssignResourceFromResourceGroupService' do
+        expect_next_instance_of(Ci::ResourceGroups::AssignResourceFromResourceGroupService, resource_group.project, nil) do |service|
+          expect(service).to receive(:execute).with(resource_group)
+        end
+
+        subject
+      end
+    end
+
+    context 'when build does not exist' do
+      let(:resource_group_id) { 123 }
+
+      it 'does not execute AssignResourceFromResourceGroupService' do
+        expect(Ci::ResourceGroups::AssignResourceFromResourceGroupService).not_to receive(:new)
+
+        subject
+      end
+    end
+  end
+end