Check if kubernetes required before creating a job

app/models/ci/pipeline.rb

@@ -32,6 +32,7 @@ module Ci
 
     delegate :id, to: :project, prefix: true
     delegate :deployment_variables, to: :project, prefix: true
+    delegate :secret_variables_for, to: :project, prefix: true
 
     validates :source, exclusion: { in: %w(unknown), unless: :importing? }, on: :create
     validates :sha, presence: { unless: :importing? }
@@ -305,6 +306,15 @@ module Ci
       @stage_seeds ||= config_processor.stage_seeds(self)
     end
 
+    def variables
+      project_secret_variables_for(ref: ref).map(&:to_runner_variable) +
+        project_deployment_variables
+    end
+
+    def has_kubernetes_available?
+      (variables.map { |v| v.fetch(:key) } & %w[KUBECONFIG KUBE_DOMAIN]).many?
+    end
+
     def has_stage_seeds?
       stage_seeds.any?
     end

lib/ci/gitlab_ci_yaml_processor.rb

@@ -44,6 +44,22 @@ module Ci
       end
     end
 
+    def pipeline_stage_builds(stage, pipeline)
+      builds = builds_for_stage_and_ref(
+        stage, pipeline.ref, pipeline.tag?, pipeline.source)
+
+      builds.select do |build|
+        job = @jobs[build.fetch(:name).to_sym]
+        has_kubernetes = pipeline.has_kubernetes_available?
+        only_kubernetes = job.dig(:only, :kubernetes)
+        except_kubernetes = job.dig(:except, :kubernetes)
+
+        [!only_kubernetes & !except_kubernetes,
+          only_kubernetes & has_kubernetes,
+          except_kubernetes & !has_kubernetes].any?
+      end
+    end
+
     def builds
       @jobs.map do |name, _|
         build_attributes(name)
@@ -52,8 +68,7 @@ module Ci
 
     def stage_seeds(pipeline)
       seeds = @stages.uniq.map do |stage|
-        builds = builds_for_stage_and_ref(
-          stage, pipeline.ref, pipeline.tag?, pipeline.source)
+        builds = pipeline_stage_builds(stage, pipeline)
 
         Gitlab::Ci::Stage::Seed.new(pipeline, stage, builds) if builds.any?
       end

lib/gitlab/ci/config/entry/policy.rb

@@ -7,7 +7,7 @@ module Gitlab
         #
         class Policy < Simplifiable
           strategy :RefsPolicy, if: -> (config) { config.is_a?(Array) }
-          strategy :ExpressionsPolicy, if: -> (config) { config.is_a?(Hash) }
+          strategy :ComplexPolicy, if: -> (config) { config.is_a?(Hash) }
 
           class RefsPolicy < Entry::Node
             include Entry::Validatable
@@ -21,20 +21,19 @@ module Gitlab
             end
           end
 
-          class ExpressionsPolicy < Entry::Node
+          class ComplexPolicy < Entry::Node
             include Entry::Validatable
             include Entry::Attributable
 
-            attributes :refs, :expressions
+            attributes :refs, :kubernetes
 
             validations do
               validates :config, presence: true
-              validates :config, allowed_keys: %i[refs expressions]
+              validates :config, allowed_keys: %i[refs kubernetes]
 
               with_options allow_nil: true do
                 validates :refs, array_of_strings_or_regexps: true
-                validates :expressions, type: Array
-                validates :expressions, presence: true
+                validates :kubernetes, inclusion: { in: [true] }
               end
             end
           end

spec/lib/ci/gitlab_ci_yaml_processor_spec.rb

@@ -164,6 +164,46 @@ module Ci
           expect(seeds.first.builds.dig(0, :name)).to eq 'spinach'
         end
       end
+
+      context 'when kubernetes policy is specified' do
+        let(:pipeline) { create(:ci_empty_pipeline) }
+
+        let(:config) do
+          YAML.dump(
+            spinach: { stage: 'test', script: 'spinach' },
+            production: { stage: 'deploy', script: 'cap', only: {
+                          kubernetes: true } }
+          )
+        end
+
+        context 'when kubernetes is configured' do
+          let(:project) { create(:kubernetes_project) }
+          let(:pipeline) { create(:ci_empty_pipeline, project: project) }
+
+          before do
+            create(:ci_variable, key: 'KUBE_DOMAIN',
+                                 protected: false,
+                                 project: project)
+          end
+
+          it 'returns seeds for kubernetes dependent job' do
+            seeds = subject.stage_seeds(pipeline)
+
+            expect(seeds.size).to eq 2
+            expect(seeds.first.builds.dig(0, :name)).to eq 'spinach'
+            expect(seeds.second.builds.dig(0, :name)).to eq 'production'
+          end
+        end
+
+        context 'when kubernetes is not configured' do
+          it 'does not return seeds for kubernetes dependent job' do
+            seeds = subject.stage_seeds(pipeline)
+
+            expect(seeds.size).to eq 1
+            expect(seeds.first.builds.dig(0, :name)).to eq 'spinach'
+          end
+        end
+      end
     end
 
     describe "#builds_for_ref" do

spec/models/ci/pipeline_spec.rb

@@ -542,6 +542,46 @@ describe Ci::Pipeline, :mailer do
     end
   end
 
+  context 'when kubernetes is configured' do
+    let(:project) { create(:kubernetes_project) }
+
+    before do
+      create(:ci_variable, key: 'KUBE_DOMAIN',
+                           protected: false,
+                           project: project)
+    end
+
+    describe '#variables' do
+      it 'returns kubernetes-related variables' do
+        variables = pipeline.variables.map { |v| v.fetch(:key) }
+
+        expect(variables).to include 'KUBECONFIG', 'KUBE_DOMAIN'
+      end
+    end
+
+    describe '#has_kubernetes_available?' do
+      it 'returns true' do
+        expect(pipeline).to have_kubernetes_available
+      end
+    end
+  end
+
+  context 'when kubernetes is not configured' do
+    describe '#variables' do
+      it 'does not return kubernetes related variables' do
+        variables = pipeline.variables.map { |v| v.fetch(:key) }
+
+        expect(variables).not_to include 'KUBECONFIG', 'KUBE_DOMAIN'
+      end
+    end
+
+    describe '#has_kubernetes_available?' do
+      it 'returns false' do
+        expect(pipeline).not_to have_kubernetes_available
+      end
+    end
+  end
+
   describe '#has_stage_seeds?' do
     context 'when pipeline has stage seeds' do
       subject { build(:ci_pipeline_with_one_job) }