Use separate Kubernetes namespaces per environment

Kubernetes deployments on new clusters will now have
a separate namespace per project environment, instead
of sharing a single namespace for the project.

Behaviour of existing clusters is unchanged.

All new functionality is controlled by the
:kubernetes_namespace_per_environment feature flag,
which is safe to enable/disable at any time.

spec/support/prometheus/additional_metrics_shared_examples.rb

@@ -50,7 +50,7 @@ RSpec.shared_examples 'additional metrics query' do
         let!(:cluster) { create(:cluster, :project, :provided_by_gcp) }
         let(:project) { cluster.project }
         let(:environment) { create(:environment, slug: 'environment-slug', project: project) }
-        let(:kube_namespace) { project.deployment_platform.kubernetes_namespace_for(project) }
+        let(:kube_namespace) { environment.deployment_namespace }
         it_behaves_like 'query context containing environment slug and filter'

spec/support/services/clusters/create_service_shared.rb

@@ -32,23 +32,56 @@ shared_context 'invalid cluster create params' do
 end
 shared_examples 'create cluster service success' do
-  it 'creates a cluster object and performs a worker' do
-    expect(ClusterProvisionWorker).to receive(:perform_async)
-
-    expect { subject }
-      .to change { Clusters::Cluster.count }.by(1)
-      .and change { Clusters::Providers::Gcp.count }.by(1)
-
-    expect(subject.name).to eq('test-cluster')
-    expect(subject.user).to eq(user)
-    expect(subject.project).to eq(project)
-    expect(subject.provider.gcp_project_id).to eq('gcp-project')
-    expect(subject.provider.zone).to eq('us-central1-a')
-    expect(subject.provider.num_nodes).to eq(1)
-    expect(subject.provider.machine_type).to eq('machine_type-a')
-    expect(subject.provider.access_token).to eq(access_token)
-    expect(subject.provider).to be_legacy_abac
-    expect(subject.platform).to be_nil
+  context 'namespace per environment feature is enabled' do
+    before do
+      stub_feature_flags(kubernetes_namespace_per_environment: true)
+    end
+
+    it 'creates a cluster object and performs a worker' do
+      expect(ClusterProvisionWorker).to receive(:perform_async)
+
+      expect { subject }
+        .to change { Clusters::Cluster.count }.by(1)
+        .and change { Clusters::Providers::Gcp.count }.by(1)
+
+      expect(subject.name).to eq('test-cluster')
+      expect(subject.user).to eq(user)
+      expect(subject.project).to eq(project)
+      expect(subject.provider.gcp_project_id).to eq('gcp-project')
+      expect(subject.provider.zone).to eq('us-central1-a')
+      expect(subject.provider.num_nodes).to eq(1)
+      expect(subject.provider.machine_type).to eq('machine_type-a')
+      expect(subject.provider.access_token).to eq(access_token)
+      expect(subject.provider).to be_legacy_abac
+      expect(subject.platform).to be_nil
+      expect(subject.namespace_per_environment).to eq true
+    end
+  end
+
+  context 'namespace per environment feature is disabled' do
+    before do
+      stub_feature_flags(kubernetes_namespace_per_environment: false)
+    end
+
+    it 'creates a cluster object and performs a worker' do
+      expect(ClusterProvisionWorker).to receive(:perform_async)
+
+      expect { subject }
+        .to change { Clusters::Cluster.count }.by(1)
+        .and change { Clusters::Providers::Gcp.count }.by(1)
+
+      expect(subject.name).to eq('test-cluster')
+      expect(subject.user).to eq(user)
+      expect(subject.project).to eq(project)
+      expect(subject.provider.gcp_project_id).to eq('gcp-project')
+      expect(subject.provider.zone).to eq('us-central1-a')
+      expect(subject.provider.num_nodes).to eq(1)
+      expect(subject.provider.machine_type).to eq('machine_type-a')
+      expect(subject.provider.access_token).to eq(access_token)
+      expect(subject.provider).to be_legacy_abac
+      expect(subject.platform).to be_nil
+      expect(subject.namespace_per_environment).to eq false
+    end
   end
 end