Stop matching on legacy app label

From now on, only match on the annotations, instead of falling back to
legacy app label. This enables users to use the app label for other
purposes such as helm charts.

ee/changelogs/unreleased/remove-support-for-app-label-matching.yml

+---
+title: Removes support for matching on app label for Kubernetes deploy boards,
+  terminals, and pod logs
+merge_request: 14020
+author:
+type: removed

ee/lib/gitlab/kubernetes/rollout_status.rb

@@ -5,8 +5,8 @@ module Gitlab
     # Calculates the rollout status for a set of kubernetes deployments.
     #
     # A GitLab environment may be composed of several Kubernetes deployments and
-    # other resources, unified by an `app=` label. The rollout status sums the
-    # Kubernetes deployments together.
+    # other resources. The rollout status sums the Kubernetes deployments
+    # together.
     class RolloutStatus
       attr_reader :deployments, :instances, :completion, :status
 

ee/spec/models/project_services/kubernetes_service_spec.rb

@@ -38,10 +38,10 @@ describe KubernetesService, models: true, use_clean_rails_memory_store_caching:
             )
           end
 
-          it 'contains legacy deployments' do
+          it 'contains nothing' do
             expect(rollout_status).to be_kind_of(::Gitlab::Kubernetes::RolloutStatus)
 
-            expect(rollout_status.deployments.map(&:name)).to contain_exactly('legacy-deployment')
+            expect(rollout_status.deployments).to eq([])
           end
         end
 

lib/gitlab/kubernetes.rb

@@ -37,15 +37,10 @@ module Gitlab
 
     # Filters an array of pods (as returned by the kubernetes API) by their project and environment
     def filter_by_project_environment(items, app, env)
-      pods = filter_by_annotation(items, {
+      filter_by_annotation(items, {
         'app.gitlab.com/app' => app,
         'app.gitlab.com/env' => env
       })
-      return pods unless pods.empty?
-
-      filter_by_label(items, {
-        'app' => env, # deprecated: replaced by app.gitlab.com/env
-      })
     end
 
     # Converts a pod (as returned by the kubernetes API) into a terminal

spec/lib/gitlab/kubernetes_spec.rb

@@ -59,16 +59,6 @@ describe Gitlab::Kubernetes do
   describe '#filter_by_project_environment' do
     let(:matching_pod) { kube_pod(environment_slug: 'production', project_slug: 'my-cool-app') }
 
-    it 'returns matching legacy env label' do
-      matching_pod['metadata']['annotations'].delete('app.gitlab.com/app')
-      matching_pod['metadata']['annotations'].delete('app.gitlab.com/env')
-      matching_pod['metadata']['labels']['app'] = 'production'
-      matching_items = [matching_pod]
-      items = matching_items + [kube_pod]
-
-      expect(filter_by_project_environment(items, 'my-cool-app', 'production')).to eq(matching_items)
-    end
-
     it 'returns matching env label' do
       matching_items = [matching_pod]
       items = matching_items + [kube_pod]