Remove api_groups from KubeClient constructor

We should have access to #core_client, #rbac_client,
and #extensions_client without having to pass in an awkward array.

Also change api_version to default_api_version, which allows us to use a
different version for an individual client. Special case for
apis/extensions which only go up to v1beta1

Makes #hashed_client private

Removes the #clients and #discover! methods which are un-used

2 files changed, 59 insertions, 117 deletions

diff --git a/lib/gitlab/kubernetes/kube_client.rb b/lib/gitlab/kubernetes/kube_client.rb
index 588238de608..0125b6005cf 100644
--- a/lib/gitlab/kubernetes/kube_client.rb
+++ b/lib/gitlab/kubernetes/kube_client.rb
@@ -19,6 +19,8 @@ module Gitlab
         'apis/extensions'
       ].freeze
 
+      LATEST_EXTENSIONS_VERSION = 'v1beta1'
+
       # Core API methods delegates to the core api group client
       delegate :get_pods,
         :get_secrets,
@@ -55,48 +57,39 @@ module Gitlab
         :watch_pod_log,
         to: :core_client
 
-      def initialize(api_prefix, api_groups = ['api'], api_version = 'v1', **kubeclient_options)
-        raise ArgumentError unless check_api_groups_supported?(api_groups)
+      attr_reader :api_prefix, :kubeclient_options, :default_api_version
 
+      def initialize(api_prefix, default_api_version = 'v1', **kubeclient_options)
         @api_prefix = api_prefix
-        @api_groups = api_groups
-        @api_version = api_version
         @kubeclient_options = kubeclient_options
-      end
+        @default_api_version = default_api_version
 
-      def discover!
-        clients.each(&:discover)
+        @hashed_clients = {}
       end
 
-      def clients
-        hashed_clients.values
+      def core_client(api_version: default_api_version)
+        build_kubeclient('api', api_version)
       end
 
-      def core_client
-        hashed_clients['api']
+      def rbac_client(api_version: default_api_version)
+        build_kubeclient('apis/rbac.authorization.k8s.io', api_version)
       end
 
-      def rbac_client
-        hashed_clients['apis/rbac.authorization.k8s.io']
+      def extensions_client(api_version: LATEST_EXTENSIONS_VERSION)
+        build_kubeclient('apis/extensions', api_version)
       end
 
-      def extensions_client
-        hashed_clients['apis/extensions']
-      end
+      private
 
-      def hashed_clients
-        strong_memoize(:hashed_clients) do
-          @api_groups.map do |api_group|
-            api_url = join_api_url(@api_prefix, api_group)
-            [api_group, ::Kubeclient::Client.new(api_url, @api_version, **@kubeclient_options)]
-          end.to_h
-        end
-      end
+      def build_kubeclient(api_group, api_version)
+        raise ArgumentError, "Unknown api group #{api_group}" unless SUPPORTED_API_GROUPS.include?(api_group)
 
-      private
+        key = api_group_with_version(api_group, api_version)
+        @hashed_clients[key] ||= ::Kubeclient::Client.new(join_api_url(api_prefix, api_group), api_version, **kubeclient_options)
+      end
 
-      def check_api_groups_supported?(api_groups)
-        api_groups.all? {|api_group| SUPPORTED_API_GROUPS.include?(api_group) }
+      def api_group_with_version(api_group, api_version)
+        api_group + '/' + api_version
       end
 
       def join_api_url(api_prefix, api_path)
diff --git a/spec/lib/gitlab/kubernetes/kube_client_spec.rb b/spec/lib/gitlab/kubernetes/kube_client_spec.rb
index 53c5a4e7c94..ba38e2c31ea 100644
--- a/spec/lib/gitlab/kubernetes/kube_client_spec.rb
+++ b/spec/lib/gitlab/kubernetes/kube_client_spec.rb
@@ -6,103 +6,87 @@ describe Gitlab::Kubernetes::KubeClient do
   include KubernetesHelpers
 
   let(:api_url) { 'https://kubernetes.example.com/prefix' }
-  let(:api_groups) { ['api', 'apis/rbac.authorization.k8s.io'] }
   let(:api_version) { 'v1' }
   let(:kubeclient_options) { { auth_options: { bearer_token: 'xyz' } } }
 
-  let(:client) { described_class.new(api_url, api_groups, api_version, kubeclient_options) }
+  let(:client) { described_class.new(api_url, api_version, kubeclient_options) }
 
   before do
     stub_kubeclient_discover(api_url)
   end
 
-  describe '#hashed_clients' do
-    subject { client.hashed_clients }
-
-    it 'has keys from api groups' do
-      expect(subject.keys).to match_array api_groups
+  shared_examples 'a Kubeclient' do
+    it 'is a Kubeclient::Client' do
+      is_expected.to be_an_instance_of Kubeclient::Client
     end
 
-    it 'has values of Kubeclient::Client' do
-      expect(subject.values).to all(be_an_instance_of Kubeclient::Client)
+    it 'has the kubeclient options' do
+      expect(subject.auth_options).to eq({ bearer_token: 'xyz' })
     end
   end
 
-  describe '#clients' do
-    subject { client.clients }
-
-    it 'is not empty' do
-      is_expected.to be_present
-    end
-
-    it 'is an array of Kubeclient::Client objects' do
-      is_expected.to all(be_an_instance_of Kubeclient::Client)
-    end
-
-    it 'has each API group url' do
-      expected_urls = api_groups.map { |group| "#{api_url}/#{group}" }
+  describe '#core_client' do
+    subject { client.core_client }
 
-      expect(subject.map(&:api_endpoint).map(&:to_s)).to match_array(expected_urls)
-    end
+    it_behaves_like 'a Kubeclient'
 
-    it 'has the kubeclient options' do
-      subject.each do |client|
-        expect(client.auth_options).to eq({ bearer_token: 'xyz' })
-      end
+    it 'has the core API endpoint' do
+      expect(subject.api_endpoint.to_s).to match(%r{\/api\Z})
     end
 
     it 'has the api_version' do
-      subject.each do |client|
-        expect(client.instance_variable_get(:@api_version)).to eq('v1')
-      end
+      expect(subject.instance_variable_get(:@api_version)).to eq('v1')
     end
-  end
-
-  describe '#core_client' do
-    subject { client.core_client }
 
-    it 'is a Kubeclient::Client' do
-      is_expected.to be_an_instance_of Kubeclient::Client
-    end
+    context 'different api version' do
+      subject { client.core_client(api_version: 'v2') }
 
-    it 'has the core API endpoint' do
-      expect(subject.api_endpoint.to_s).to match(%r{\/api\Z})
+      it 'has the api_version' do
+        expect(subject.instance_variable_get(:@api_version)).to eq('v2')
+      end
     end
   end
 
   describe '#rbac_client' do
     subject { client.rbac_client }
 
-    it 'is a Kubeclient::Client' do
-      is_expected.to be_an_instance_of Kubeclient::Client
-    end
+    it_behaves_like 'a Kubeclient'
 
     it 'has the RBAC API group endpoint' do
       expect(subject.api_endpoint.to_s).to match(%r{\/apis\/rbac.authorization.k8s.io\Z})
     end
+
+    it 'has the api_version' do
+      expect(subject.instance_variable_get(:@api_version)).to eq('v1')
+    end
+
+    context 'different api version' do
+      subject { client.rbac_client(api_version: 'v2') }
+
+      it 'has the api_version' do
+        expect(subject.instance_variable_get(:@api_version)).to eq('v2')
+      end
+    end
   end
 
   describe '#extensions_client' do
     subject { client.extensions_client }
 
-    let(:api_groups) { ['apis/extensions'] }
-
-    it 'is a Kubeclient::Client' do
-      is_expected.to be_an_instance_of Kubeclient::Client
-    end
+    it_behaves_like 'a Kubeclient'
 
     it 'has the extensions API group endpoint' do
       expect(subject.api_endpoint.to_s).to match(%r{\/apis\/extensions\Z})
     end
-  end
 
-  describe '#discover!' do
-    it 'makes a discovery request for each API group' do
-      client.discover!
+    it 'has the api_version' do
+      expect(subject.instance_variable_get(:@api_version)).to eq('v1beta1')
+    end
 
-      api_groups.each do |api_group|
-        discovery_url = api_url + '/' + api_group + '/v1'
-        expect(WebMock).to have_requested(:get, discovery_url).once
+    context 'different api version' do
+      subject { client.extensions_client(api_version: 'v2') }
+
+      it 'has the api_version' do
+        expect(subject.instance_variable_get(:@api_version)).to eq('v2')
       end
     end
   end
@@ -156,14 +140,6 @@ describe Gitlab::Kubernetes::KubeClient do
         it 'responds to the method' do
           expect(client).to respond_to method
         end
-
-        context 'no rbac client' do
-          let(:api_groups) { ['api'] }
-
-          it 'throws an error' do
-            expect { client.public_send(method) }.to raise_error(Module::DelegationError)
-          end
-        end
       end
     end
   end
@@ -181,22 +157,11 @@ describe Gitlab::Kubernetes::KubeClient do
       it 'responds to the method' do
         expect(client).to respond_to :get_deployments
       end
-
-      context 'no extensions client' do
-        let(:api_groups) { ['api'] }
-        let(:api_version) { 'v1' }
-
-        it 'throws an error' do
-          expect { client.get_deployments }.to raise_error(Module::DelegationError)
-        end
-      end
     end
   end
 
   describe 'non-entity methods' do
     it 'does not proxy for non-entity methods' do
-      expect(client.clients.first).to respond_to :proxy_url
-
       expect(client).not_to respond_to :proxy_url
     end
 
@@ -211,14 +176,6 @@ describe Gitlab::Kubernetes::KubeClient do
     it 'is delegated to the core client' do
       expect(client).to delegate_method(:get_pod_log).to(:core_client)
     end
-
-    context 'when no core client' do
-      let(:api_groups) { ['apis/extensions'] }
-
-      it 'throws an error' do
-        expect { client.get_pod_log('pod-name') }.to raise_error(Module::DelegationError)
-      end
-    end
   end
 
   describe '#watch_pod_log' do
@@ -227,14 +184,6 @@ describe Gitlab::Kubernetes::KubeClient do
     it 'is delegated to the core client' do
       expect(client).to delegate_method(:watch_pod_log).to(:core_client)
     end
-
-    context 'when no core client' do
-      let(:api_groups) { ['apis/extensions'] }
-
-      it 'throws an error' do
-        expect { client.watch_pod_log('pod-name') }.to raise_error(Module::DelegationError)
-      end
-    end
   end
 
   describe 'methods that do not exist on any client' do