Fix connection to Tiller error while uninstalling

Both the `install-<app>` and `uninstall-<app>` pods loads the
`values-content-configuration-<app>` configmap into the pod
(see `#volume_specification`). This configmap contains the cert
necessary to connect to Tiller. The cert though is only valid for 30
minutes.

So this fixes the bug where the configmap when uninstalling should be
updated as well.

changelogs/unreleased/62713-fix-uninstalling-cluster-apps.yml

+---
+title: Fix connection to Tiller error while uninstalling
+merge_request: 29131
+author:
+type: fixed

lib/gitlab/kubernetes/helm/api.rb

@@ -24,6 +24,7 @@ module Gitlab
 
         def uninstall(command)
           namespace.ensure_exists!
+          create_config_map(command)
 
           delete_pod!(command.pod_name)
           kubeclient.create_pod(command.pod_resource)

spec/lib/gitlab/kubernetes/helm/api_spec.rb

@@ -36,6 +36,8 @@ describe Gitlab::Kubernetes::Helm::Api do
   describe '#uninstall' do
     before do
       allow(client).to receive(:create_pod).and_return(nil)
+      allow(client).to receive(:get_config_map).and_return(nil)
+      allow(client).to receive(:create_config_map).and_return(nil)
       allow(client).to receive(:delete_pod).and_return(nil)
       allow(namespace).to receive(:ensure_exists!).once
     end
@@ -53,6 +55,28 @@ describe Gitlab::Kubernetes::Helm::Api do
 
       subject.uninstall(command)
     end
+
+    context 'with a ConfigMap' do
+      let(:resource) { Gitlab::Kubernetes::ConfigMap.new(application_name, files).generate }
+
+      it 'creates a ConfigMap on kubeclient' do
+        expect(client).to receive(:create_config_map).with(resource).once
+
+        subject.install(command)
+      end
+
+      context 'config map already exists' do
+        before do
+          expect(client).to receive(:get_config_map).with("values-content-configuration-#{application_name}", gitlab_namespace).and_return(resource)
+        end
+
+        it 'updates the config map' do
+          expect(client).to receive(:update_config_map).with(resource).once
+
+          subject.install(command)
+        end
+      end
+    end
   end
 
   describe '#install' do