Allow operators to control feature gates

jobs/kube-apiserver/spec

@@ -41,6 +41,8 @@ properties:
   enable_audit_logs:
     description: Enables audit logs
     default: true
+  feature_gates:
+    description: A map of key=value pairs that describe alpha or experimental features.
   http_proxy:
     description: http_proxy env var for the kubernetes-api binary (i.e. for cloud provider interactions)
   https_proxy:

jobs/kube-apiserver/templates/config/bpm.yml.erb

@@ -40,6 +40,9 @@ processes:
   - --enable-swagger-ui
   - --etcd-servers=<%= etcd_endpoints %>
   - --etcd-cafile=/var/vcap/jobs/kube-apiserver/config/etcd-ca.crt
+  <% if_p('feature_gates') do |feature_gates| %>
+  - --feature-gates=<%= feature_gates.flat_map {|k,v| "#{k}=#{v}"}.join(",") %>
+  <% end %>
   - --etcd-certfile=/var/vcap/jobs/kube-apiserver/config/etcd-client.crt
   - --etcd-keyfile=/var/vcap/jobs/kube-apiserver/config/etcd-client.key
   - --kubelet-https

spec/kube_apiserver_bpm_yml_spec.rb

@@ -152,7 +152,7 @@
     expect(bpm_yml['processes'][0]['env']['HTTPS_PROXY']).to eq('proxy.example.com:8100')
   end
 
-  fit 'sets no_proxy when no proxy property is set' do
+  it 'sets no_proxy when no proxy property is set' do
     rendered_kube_apiserver_bpm_yml = compiled_template(
       'kube-apiserver',
       'config/bpm.yml',
@@ -166,4 +166,21 @@
     expect(bpm_yml['processes'][0]['env']['no_proxy']).to eq('noproxy.example.com,noproxy.example.net')
     expect(bpm_yml['processes'][0]['env']['NO_PROXY']).to eq('noproxy.example.com,noproxy.example.net')
   end
+
+  it 'sets feature gates if the property is defined' do
+    rendered_kube_apiserver_bpm_yml = compiled_template(
+      'kube-apiserver',
+      'config/bpm.yml',
+      {
+        'feature_gates' => {
+          'CustomFeature1' => true,
+          'CustomFeature2' => false
+        }
+      },
+      link_spec
+    )
+
+    bpm_yml = YAML.safe_load(rendered_kube_apiserver_bpm_yml)
+    expect(bpm_yml['processes'][0]['args']).to include('--feature-gates=CustomFeature1=true,CustomFeature2=false')
+  end
 end