Implement suggestions on Knative RBAC from @tkuah

Relates to https://gitlab.com/gitlab-org/gitlab/merge_requests/20244Co-Authored-By: Thong Kuah <tkuah@gitlab.com>

app/finders/clusters/knative_serving_namespace_finder.rb

+# frozen_string_literal: true
+
+module Clusters
+  class KnativeServingNamespaceFinder
+    attr_reader :cluster
+
+    def initialize(cluster)
+      @cluster = cluster
+    end
+
+    def execute
+      cluster.kubeclient&.get_namespace(Clusters::Kubernetes::KNATIVE_SERVING_NAMESPACE)
+    rescue Kubeclient::ResourceNotFoundError
+      nil
+    end
+  end
+end

app/finders/clusters/knative_version_role_binding_finder.rb

@@ -9,9 +9,9 @@ module Clusters
     end
 
     def execute
-      cluster&.kubeclient&.get_cluster_role_bindings&.find do |resource|
-        resource.metadata.name == Clusters::Kubernetes::GITLAB_KNATIVE_VERSION_ROLE_BINDING_NAME
-      end
+      cluster.kubeclient&.get_cluster_role_binding(Clusters::Kubernetes::GITLAB_KNATIVE_VERSION_ROLE_BINDING_NAME)
+    rescue Kubeclient::ResourceNotFoundError
+      nil
     end
   end
 end

app/services/clusters/kubernetes/create_or_update_service_account_service.rb

@@ -71,9 +71,9 @@ module Clusters
       end
 
       def knative_serving_namespace
-        kubeclient.core_client.get_namespaces.find do |namespace|
-          namespace.metadata.name == Clusters::Kubernetes::KNATIVE_SERVING_NAMESPACE
-        end
+        kubeclient.get_namespace(Clusters::Kubernetes::KNATIVE_SERVING_NAMESPACE)
+      rescue Kubeclient::ResourceNotFoundError
+        nil
       end
 
       def create_role_or_cluster_role_binding

lib/gitlab/ci/build/prerequisite/kubernetes_namespace.rb

@@ -8,7 +8,7 @@ module Gitlab
           def unmet?
             deployment_cluster.present? &&
               deployment_cluster.managed? &&
-              (missing_namespace? || missing_knative_version_role_binding?)
+              (missing_namespace? || need_knative_version_role_binding?)
           end
 
           def complete!
@@ -23,8 +23,8 @@ module Gitlab
             kubernetes_namespace.nil? || kubernetes_namespace.service_account_token.blank?
           end
 
-          def missing_knative_version_role_binding?
-            knative_version_role_binding.nil?
+          def need_knative_version_role_binding?
+            !knative_serving_namespace.nil? && knative_version_role_binding.nil?
           end
 
           def deployment_cluster
@@ -35,6 +35,14 @@ module Gitlab
             build.deployment.environment
           end
 
+          def knative_serving_namespace
+            strong_memoize(:knative_serving_namespace) do
+              Clusters::KnativeServingNamespaceFinder.new(
+                deployment_cluster
+              ).execute
+            end
+          end
+
           def knative_version_role_binding
             strong_memoize(:knative_version_role_binding) do
               Clusters::KnativeVersionRoleBindingFinder.new(

spec/lib/gitlab/ci/build/prerequisite/kubernetes_namespace_spec.rb

@@ -38,28 +38,44 @@ describe Gitlab::Ci::Build::Prerequisite::KubernetesNamespace do
               .and_return(double(execute: kubernetes_namespace))
           end
 
-          context 'and the knative version role binding is missing' do
+          context 'and the knative-serving namespace is missing' do
             before do
-              allow(Clusters::KnativeVersionRoleBindingFinder).to receive(:new)
-                .and_return(double(execute: nil))
+              allow(Clusters::KnativeServingNamespaceFinder).to receive(:new)
+                .and_return(double(execute: false))
             end
 
             it { is_expected.to be_truthy }
           end
 
-          context 'and the knative version role binding already exists' do
+          context 'and the knative-serving namespace exists' do
             before do
-              allow(Clusters::KnativeVersionRoleBindingFinder).to receive(:new)
+              allow(Clusters::KnativeServingNamespaceFinder).to receive(:new)
                 .and_return(double(execute: true))
             end
 
-            it { is_expected.to be_falsey }
-
-            context 'and the service_account_token is blank' do
-              let(:kubernetes_namespace) { instance_double(Clusters::KubernetesNamespace, service_account_token: nil) }
+            context 'and the knative version role binding is missing' do
+              before do
+                allow(Clusters::KnativeVersionRoleBindingFinder).to receive(:new)
+                  .and_return(double(execute: nil))
+              end
 
               it { is_expected.to be_truthy }
             end
+
+            context 'and the knative version role binding already exists' do
+              before do
+                allow(Clusters::KnativeVersionRoleBindingFinder).to receive(:new)
+                  .and_return(double(execute: true))
+              end
+
+              it { is_expected.to be_falsey }
+
+              context 'and the service_account_token is blank' do
+                let(:kubernetes_namespace) { instance_double(Clusters::KubernetesNamespace, service_account_token: nil) }
+
+                it { is_expected.to be_truthy }
+              end
+            end
           end
         end
       end

spec/services/clusters/kubernetes/create_or_update_namespace_service_spec.rb

@@ -22,7 +22,6 @@ describe Clusters::Kubernetes::CreateOrUpdateNamespaceService, '#execute' do
 
   before do
     stub_kubeclient_discover(api_url)
-    stub_kubeclient_get_namespaces(api_url)
     stub_kubeclient_get_service_account_error(api_url, 'gitlab')
     stub_kubeclient_create_service_account(api_url)
     stub_kubeclient_get_secret_error(api_url, 'gitlab-token')
@@ -31,6 +30,7 @@ describe Clusters::Kubernetes::CreateOrUpdateNamespaceService, '#execute' do
     stub_kubeclient_get_role_binding(api_url, "gitlab-#{namespace}", namespace: namespace)
     stub_kubeclient_put_role_binding(api_url, "gitlab-#{namespace}", namespace: namespace)
     stub_kubeclient_get_namespace(api_url, namespace: namespace)
+    stub_kubeclient_get_namespace(api_url, namespace: Clusters::Kubernetes::KNATIVE_SERVING_NAMESPACE)
     stub_kubeclient_get_service_account_error(api_url, "#{namespace}-service-account", namespace: namespace)
     stub_kubeclient_create_service_account(api_url, namespace: namespace)
     stub_kubeclient_create_secret(api_url, namespace: namespace)

spec/services/clusters/kubernetes/create_or_update_service_account_service_spec.rb

@@ -141,7 +141,7 @@ describe Clusters::Kubernetes::CreateOrUpdateServiceAccountService do
       before do
         cluster.platform_kubernetes.rbac!
 
-        stub_kubeclient_get_namespaces(api_url)
+        stub_kubeclient_get_namespace(api_url, namespace: Clusters::Kubernetes::KNATIVE_SERVING_NAMESPACE)
         stub_kubeclient_get_role_binding_error(api_url, role_binding_name, namespace: namespace)
         stub_kubeclient_create_role_binding(api_url, namespace: namespace)
         stub_kubeclient_put_role(api_url, Clusters::Kubernetes::GITLAB_KNATIVE_SERVING_ROLE_NAME, namespace: namespace)