Revert KubernetesService logic in Platforms::Kubernetes

app/models/clusters/platforms/kubernetes.rb

 module Clusters
   module Platforms
     class Kubernetes < ActiveRecord::Base
+      include Gitlab::CurrentSettings
+      include Gitlab::Kubernetes
+      include ReactiveCaching
+
       self.table_name = 'cluster_platforms_kubernetes'
+      self.reactive_cache_key = ->(kubernetes) { [kubernetes.class.model_name.singular, kubernetes.cluster_id] }
 
       belongs_to :cluster, inverse_of: :platform_kubernetes, class_name: 'Clusters::Cluster'
 
@@ -29,6 +34,8 @@ module Clusters
       validates :api_url, url: true, presence: true
       validates :token, presence: true
 
+      after_save :clear_reactive_cache!
+
       # TODO: Glue code till we migrate Kubernetes Integration into Platforms::Kubernetes
       after_destroy :destroy_kubernetes_integration!
 
@@ -55,6 +62,80 @@ module Clusters
         self.class.namespace_for_project(project) if project
       end
 
+      def predefined_variables
+        config = YAML.dump(kubeconfig)
+
+        variables = [
+          { key: 'KUBE_URL', value: api_url, public: true },
+          { key: 'KUBE_TOKEN', value: token, public: false },
+          { key: 'KUBE_NAMESPACE', value: actual_namespace, public: true },
+          { key: 'KUBECONFIG', value: config, public: false, file: true }
+        ]
+
+        if ca_pem.present?
+          variables << { key: 'KUBE_CA_PEM', value: ca_pem, public: true }
+          variables << { key: 'KUBE_CA_PEM_FILE', value: ca_pem, public: true, file: true }
+        end
+
+        variables
+      end
+
+      # Constructs a list of terminals from the reactive cache
+      #
+      # Returns nil if the cache is empty, in which case you should try again a
+      # short time later
+      def terminals(environment)
+        with_reactive_cache do |data|
+          pods = filter_by_label(data[:pods], app: environment.slug)
+          terminals = pods.flat_map { |pod| terminals_for_pod(api_url, actual_namespace, pod) }
+          terminals.each { |terminal| add_terminal_auth(terminal, terminal_auth) }
+        end
+      end
+
+      # Caches resources in the namespace so other calls don't need to block on
+      # network access
+      def calculate_reactive_cache
+        return unless active? && project && !project.pending_delete?
+
+        # We may want to cache extra things in the future
+        { pods: read_pods }
+      end
+
+      def kubeconfig
+        to_kubeconfig(
+          url: api_url,
+          namespace: actual_namespace,
+          token: token,
+          ca_pem: ca_pem)
+      end
+
+      def read_secrets
+        kubeclient = build_kubeclient!
+
+        kubeclient.get_secrets.as_json
+      end
+
+      # Returns a hash of all pods in the namespace
+      def read_pods
+        kubeclient = build_kubeclient!
+
+        kubeclient.get_pods(namespace: actual_namespace).as_json
+      rescue KubeException => err
+        raise err unless err.error_code == 404
+        []
+      end
+
+      def kubeclient_ssl_options
+        opts = { verify_ssl: OpenSSL::SSL::VERIFY_PEER }
+
+        if ca_pem.present?
+          opts[:cert_store] = OpenSSL::X509::Store.new
+          opts[:cert_store].add_cert(OpenSSL::X509::Certificate.new(ca_pem))
+        end
+
+        opts
+      end
+
       def kubeclient
         @kubeclient ||= kubernetes_service.kubeclient if manages_kubernetes_service?
       end
@@ -104,6 +185,48 @@ module Clusters
       def ensure_kubernetes_service
         @kubernetes_service ||= kubernetes_service || project&.build_kubernetes_service
       end
+
+      def build_kubeclient!(api_path: 'api', api_version: 'v1')
+        raise "Incomplete settings" unless api_url && actual_namespace
+
+        unless (username && password) || token
+          raise "Either username/password or token is required to access API"
+        end
+
+        ::Kubeclient::Client.new(
+          join_api_url(api_path),
+          api_version,
+          auth_options: kubeclient_auth_options,
+          ssl_options: kubeclient_ssl_options,
+          http_proxy_uri: ENV['http_proxy']
+        )
+      end
+
+      def kubeclient_auth_options
+        return { username: username, password: password } if username && password
+        return { bearer_token: token } if token
+      end
+
+      def join_api_url(api_path)
+        url = URI.parse(api_url)
+        prefix = url.path.sub(%r{/+\z}, '')
+
+        url.path = [prefix, api_path].join("/")
+
+        url.to_s
+      end
+
+      def terminal_auth
+        {
+          token: token,
+          ca_pem: ca_pem,
+          max_session_time: current_application_settings.terminal_max_session_time
+        }
+      end
+
+      def enforce_namespace_to_lower_case
+        self.namespace = self.namespace&.downcase
+      end
     end
   end
 end

spec/models/clusters/platforms/kubernetes_spec.rb

@@ -5,6 +5,8 @@ describe Clusters::Platforms::Kubernetes, :use_clean_rails_memory_store_caching
   include ReactiveCachingHelpers
 
   it { is_expected.to belong_to(:cluster) }
+  it { is_expected.to be_kind_of(Gitlab::Kubernetes) }
+  it { is_expected.to be_kind_of(ReactiveCaching) }
   it { is_expected.to respond_to :ca_pem }
 
   describe 'before_validation' do
@@ -185,4 +187,137 @@ describe Clusters::Platforms::Kubernetes, :use_clean_rails_memory_store_caching
       it { is_expected.to be_nil }
     end
   end
+
+  describe '#predefined_variables' do
+    let!(:cluster) { create(:cluster, :project, platform_kubernetes: kubernetes) }
+    let(:kubernetes) { create(:platform_kubernetes, api_url: api_url, ca_cert: ca_pem, token: token) }
+    let(:api_url) { 'https://kube.domain.com' }
+    let(:ca_pem) { 'CA PEM DATA' }
+    let(:token) { 'token' }
+
+    let(:kubeconfig) do
+      config_file = expand_fixture_path('config/kubeconfig.yml')
+      config = YAML.load(File.read(config_file))
+      config.dig('users', 0, 'user')['token'] = token
+      config.dig('contexts', 0, 'context')['namespace'] = namespace
+      config.dig('clusters', 0, 'cluster')['certificate-authority-data'] =
+        Base64.strict_encode64(ca_pem)
+
+      YAML.dump(config)
+    end
+
+    shared_examples 'setting variables' do
+      it 'sets the variables' do
+        expect(kubernetes.predefined_variables).to include(
+          { key: 'KUBE_URL', value: api_url, public: true },
+          { key: 'KUBE_TOKEN', value: token, public: false },
+          { key: 'KUBE_NAMESPACE', value: namespace, public: true },
+          { key: 'KUBECONFIG', value: kubeconfig, public: false, file: true },
+          { key: 'KUBE_CA_PEM', value: ca_pem, public: true },
+          { key: 'KUBE_CA_PEM_FILE', value: ca_pem, public: true, file: true }
+        )
+      end
+    end
+
+    context 'namespace is provided' do
+      let(:namespace) { 'my-project' }
+
+      before do
+        kubernetes.namespace = namespace
+      end
+
+      it_behaves_like 'setting variables'
+    end
+
+    context 'no namespace provided' do
+      let(:namespace) { kubernetes.actual_namespace }
+
+      it_behaves_like 'setting variables'
+
+      it 'sets the KUBE_NAMESPACE' do
+        kube_namespace = kubernetes.predefined_variables.find { |h| h[:key] == 'KUBE_NAMESPACE' }
+
+        expect(kube_namespace).not_to be_nil
+        expect(kube_namespace[:value]).to match(/\A#{Gitlab::PathRegex::PATH_REGEX_STR}-\d+\z/)
+      end
+    end
+  end
+
+  describe '#terminals' do
+    subject { service.terminals(environment) }
+
+    let!(:cluster) { create(:cluster, :project, platform_kubernetes: service) }
+    let(:project) { cluster.project }
+    let(:service) { create(:platform_kubernetes, :configured) }
+    let(:environment) { build(:environment, project: project, name: "env", slug: "env-000000") }
+
+    context 'with invalid pods' do
+      it 'returns no terminals' do
+        stub_reactive_cache(service, pods: [{ "bad" => "pod" }])
+
+        is_expected.to be_empty
+      end
+    end
+
+    context 'with valid pods' do
+      let(:pod) { kube_pod(app: environment.slug) }
+      let(:terminals) { kube_terminals(service, pod) }
+
+      before do
+        stub_reactive_cache(
+          service,
+          pods: [pod, pod, kube_pod(app: "should-be-filtered-out")]
+        )
+      end
+
+      it 'returns terminals' do
+        is_expected.to eq(terminals + terminals)
+      end
+
+      it 'uses max session time from settings' do
+        stub_application_setting(terminal_max_session_time: 600)
+
+        times = subject.map { |terminal| terminal[:max_session_time] }
+        expect(times).to eq [600, 600, 600, 600]
+      end
+    end
+  end
+
+  describe '#calculate_reactive_cache' do
+    subject { service.calculate_reactive_cache }
+
+    let!(:cluster) { create(:cluster, :project, enabled: enabled, platform_kubernetes: service) }
+    let(:service) { create(:platform_kubernetes, :configured) }
+    let(:enabled) { true }
+
+    context 'when cluster is disabled' do
+      let(:enabled) { false }
+
+      it { is_expected.to be_nil }
+    end
+
+    context 'when kubernetes responds with valid pods' do
+      before do
+        stub_kubeclient_pods
+      end
+
+      it { is_expected.to eq(pods: [kube_pod]) }
+    end
+
+    context 'when kubernetes responds with 500s' do
+      before do
+        stub_kubeclient_pods(status: 500)
+      end
+
+      it { expect { subject }.to raise_error(KubeException) }
+    end
+
+    context 'when kubernetes responds with 404s' do
+      before do
+        stub_kubeclient_pods(status: 404)
+      end
+
+      it { is_expected.to eq(pods: []) }
+    end
+  end
 end