Add support for network policy k8s API resources

This patch adds new kube client for the networking.k8s.io API group and
introduces support for NetworkPolicy resources through that client.

lib/gitlab/kubernetes/kube_client.rb

@@ -19,7 +19,8 @@ module Gitlab
         apps: { group: 'apis/apps', version: 'v1' },
         extensions: { group: 'apis/extensions', version: 'v1beta1' },
         istio: { group: 'apis/networking.istio.io', version: 'v1alpha3' },
-        knative: { group: 'apis/serving.knative.dev', version: 'v1alpha1' }
+        knative: { group: 'apis/serving.knative.dev', version: 'v1alpha1' },
+        networking: { group: 'apis/networking.k8s.io', version: 'v1' }
       }.freeze
 
       SUPPORTED_API_GROUPS.each do |name, params|
@@ -88,6 +89,14 @@ module Gitlab
         :update_gateway,
         to: :istio_client
 
+      # NetworkPolicy methods delegate to the apis/networking.k8s.io api
+      # group client
+      delegate :create_network_policy,
+        :get_network_policies,
+        :update_network_policy,
+        :delete_network_policy,
+        to: :networking_client
+
       attr_reader :api_prefix, :kubeclient_options
 
       DEFAULT_KUBECLIENT_OPTIONS = {

spec/lib/gitlab/kubernetes/kube_client_spec.rb

@@ -174,6 +174,20 @@ describe Gitlab::Kubernetes::KubeClient do
     end
   end
 
+  describe '#networking_client' do
+    subject { client.networking_client }
+
+    it_behaves_like 'a Kubeclient'
+
+    it 'has the networking API group endpoint' do
+      expect(subject.api_endpoint.to_s).to match(%r{\/apis\/networking.k8s.io\Z})
+    end
+
+    it 'has the api_version' do
+      expect(subject.instance_variable_get(:@api_version)).to eq('v1')
+    end
+  end
+
   describe 'core API' do
     let(:core_client) { client.core_client }
 
@@ -290,6 +304,30 @@ describe Gitlab::Kubernetes::KubeClient do
     end
   end
 
+  describe 'networking API group' do
+    let(:networking_client) { client.networking_client }
+
+    [
+      :create_network_policy,
+      :get_network_policies,
+      :update_network_policy,
+      :delete_network_policy
+    ].each do |method|
+      describe "##{method}" do
+        include_examples 'redirection not allowed', method
+        include_examples 'dns rebinding not allowed', method
+
+        it 'delegates to the networking client' do
+          expect(client).to delegate_method(method).to(:networking_client)
+        end
+
+        it 'responds to the method' do
+          expect(client).to respond_to method
+        end
+      end
+    end
+  end
+
   describe 'non-entity methods' do
     it 'does not proxy for non-entity methods' do
       expect(client).not_to respond_to :proxy_url