Allow knative do be uninstalled:

- After uninstalling the knative helm chart it's necessary to also
remove some leftover resources to allow the cluster to be clean
and knative to be reinstalleable.
- Adds knative uninstall disclaimer
- Uninstall ksvc before uninstalling knative

Make list of Knative and Ingres resources explicit

- To avoid deleting unwanted resources we are listing exact
which resources will be deleted rather than simply deleting any
resource that contains istio or knative words.

1 files changed, 13 insertions, 0 deletions

diff --git a/app/models/clusters/applications/prometheus.rb b/app/models/clusters/applications/prometheus.rb
index 805c8a73f8c..f5375d29f3a 100644
--- a/app/models/clusters/applications/prometheus.rb
+++ b/app/models/clusters/applications/prometheus.rb
@@ -59,6 +59,15 @@ module Clusters
         )
       end
 
+      def uninstall_command
+        Gitlab::Kubernetes::Helm::DeleteCommand.new(
+          name: name,
+          rbac: cluster.platform_kubernetes_rbac?,
+          files: files,
+          predelete: delete_knative_istio_metrics.to_a
+        )
+      end
+
       # Returns a copy of files where the values of 'values.yaml'
       # are replaced by the argument.
       #
@@ -97,6 +106,10 @@ module Clusters
       def install_knative_metrics
         ["kubectl apply -f #{Clusters::Applications::Knative::METRICS_CONFIG}"] if cluster.application_knative_available?
       end
+
+      def delete_knative_istio_metrics
+        ["kubectl delete -f #{Clusters::Applications::Knative::METRICS_CONFIG}"] if cluster.application_knative_available?
+      end
     end
   end
 end