Drop fallback to deployment platform

All deployments should have already their cluster_id filled in on
creation. Legacy deployments will not be retried as:-

* Ci::Build#retry calls `Ci::RetryBuildService`
* Ci::Pipeline#retry
calls `Ci::RetryPipelineService` which also calls
`Ci::RetryBuildService`
* `Ci::RetryBuildService` will clone a build to retry

It is also impossibly to backfill Deployment#cluster_id from
Project#deployment_platform correctly as clusters could have been
deleted, added or altered in the intervening time.

2 files changed, 5 insertions, 21 deletions

diff --git a/lib/gitlab/ci/build/prerequisite/kubernetes_namespace.rb b/lib/gitlab/ci/build/prerequisite/kubernetes_namespace.rb
index 48598fcae7e..e6e0aaab60b 100644
--- a/lib/gitlab/ci/build/prerequisite/kubernetes_namespace.rb
+++ b/lib/gitlab/ci/build/prerequisite/kubernetes_namespace.rb
@@ -20,9 +20,7 @@ module Gitlab
           private
 
           def deployment_cluster
-            strong_memoize(:deployment_cluster) do
-              build.deployment&.cluster || build.deployment&.deployment_platform_cluster
-            end
+            build.deployment&.cluster
           end
 
           def kubernetes_namespace
diff --git a/spec/lib/gitlab/ci/build/prerequisite/kubernetes_namespace_spec.rb b/spec/lib/gitlab/ci/build/prerequisite/kubernetes_namespace_spec.rb
index 51e16c99688..d88a2097ba2 100644
--- a/spec/lib/gitlab/ci/build/prerequisite/kubernetes_namespace_spec.rb
+++ b/spec/lib/gitlab/ci/build/prerequisite/kubernetes_namespace_spec.rb
@@ -17,15 +17,12 @@ describe Gitlab::Ci::Build::Prerequisite::KubernetesNamespace do
     end
 
     context 'build has a deployment' do
-      let!(:deployment) { create(:deployment, deployable: build) }
+      let!(:deployment) { create(:deployment, deployable: build, cluster: cluster) }
+      let(:cluster) { nil }
 
       context 'and a cluster to deploy to' do
         let(:cluster) { create(:cluster, :group) }
 
-        before do
-          allow(build.deployment).to receive(:deployment_platform_cluster).and_return(cluster)
-        end
-
         it { is_expected.to be_truthy }
 
         context 'and the cluster is not managed' do
@@ -48,28 +45,21 @@ describe Gitlab::Ci::Build::Prerequisite::KubernetesNamespace do
       end
 
       context 'and no cluster to deploy to' do
-        before do
-          expect(deployment.deployment_platform_cluster).to be_nil
-        end
-
         it { is_expected.to be_falsey }
       end
     end
   end
 
   describe '#complete!' do
-    let!(:deployment) { create(:deployment, deployable: build) }
+    let!(:deployment) { create(:deployment, deployable: build, cluster: cluster) }
     let(:service) { double(execute: true) }
+    let(:cluster) { nil }
 
     subject { described_class.new(build).complete! }
 
     context 'completion is required' do
       let(:cluster) { create(:cluster, :group) }
 
-      before do
-        allow(build.deployment).to receive(:deployment_platform_cluster).and_return(cluster)
-      end
-
       it 'creates a kubernetes namespace' do
         expect(Clusters::Gcp::Kubernetes::CreateOrUpdateNamespaceService)
           .to receive(:new)
@@ -83,10 +73,6 @@ describe Gitlab::Ci::Build::Prerequisite::KubernetesNamespace do
     end
 
     context 'completion is not required' do
-      before do
-        expect(deployment.deployment_platform_cluster).to be_nil
-      end
-
       it 'does not create a namespace' do
         expect(Clusters::Gcp::Kubernetes::CreateOrUpdateNamespaceService).not_to receive(:new)