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.

3 files changed, 81 insertions, 41 deletions

diff --git a/app/finders/clusters/knative_services_finder.rb b/app/finders/clusters/knative_services_finder.rb
index 7d3b53ef663..71cebe4495e 100644
--- a/app/finders/clusters/knative_services_finder.rb
+++ b/app/finders/clusters/knative_services_finder.rb
@@ -13,11 +13,11 @@ module Clusters
     self.reactive_cache_key = ->(finder) { finder.model_name }
     self.reactive_cache_worker_finder = ->(_id, *cache_args) { from_cache(*cache_args) }
 
-    attr_reader :cluster, :project
+    attr_reader :cluster, :environment
 
-    def initialize(cluster, project)
+    def initialize(cluster, environment)
       @cluster = cluster
-      @project = project
+      @environment = environment
     end
 
     def with_reactive_cache_memoized(*cache_args, &block)
@@ -30,11 +30,11 @@ module Clusters
       clear_reactive_cache!(*cache_args)
     end
 
-    def self.from_cache(cluster_id, project_id)
+    def self.from_cache(cluster_id, environment_id)
       cluster = Clusters::Cluster.find(cluster_id)
-      project = ::Project.find(project_id)
+      environment = Environment.find(environment_id)
 
-      new(cluster, project)
+      new(cluster, environment)
     end
 
     def calculate_reactive_cache(*)
@@ -56,7 +56,7 @@ module Clusters
     end
 
     def cache_args
-      [cluster.id, project.id]
+      [cluster.id, environment.id]
     end
 
     def service_pod_details(service)
@@ -84,7 +84,7 @@ module Clusters
     private
 
     def search_namespace
-      @search_namespace ||= cluster.kubernetes_namespace_for(project)
+      @search_namespace ||= cluster.kubernetes_namespace_for(environment)
     end
 
     def knative_client
diff --git a/app/finders/clusters/kubernetes_namespace_finder.rb b/app/finders/clusters/kubernetes_namespace_finder.rb
new file mode 100644
index 00000000000..e947796c1e7
--- /dev/null
+++ b/app/finders/clusters/kubernetes_namespace_finder.rb
@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Clusters
+  class KubernetesNamespaceFinder
+    attr_reader :cluster, :project, :environment_slug
+
+    def initialize(cluster, project:, environment_slug:, allow_blank_token: false)
+      @cluster = cluster
+      @project = project
+      @environment_slug = environment_slug
+      @allow_blank_token = allow_blank_token
+    end
+
+    def execute
+      find_namespace(with_environment: cluster.namespace_per_environment?)
+    end
+
+    private
+
+    attr_reader :allow_blank_token
+
+    def find_namespace(with_environment:)
+      relation = with_environment ? namespaces.with_environment_slug(environment_slug) : namespaces
+
+      relation.find_by_project_id(project.id)
+    end
+
+    def namespaces
+      if allow_blank_token
+        cluster.kubernetes_namespaces
+      else
+        cluster.kubernetes_namespaces.has_service_account_token
+      end
+    end
+  end
+end
diff --git a/app/finders/projects/serverless/functions_finder.rb b/app/finders/projects/serverless/functions_finder.rb
index ebe50806ca1..e8c50ef1a88 100644
--- a/app/finders/projects/serverless/functions_finder.rb
+++ b/app/finders/projects/serverless/functions_finder.rb
@@ -3,10 +3,11 @@
 module Projects
   module Serverless
     class FunctionsFinder
+      include Gitlab::Utils::StrongMemoize
+
       attr_reader :project
 
       def initialize(project)
-        @clusters = project.clusters
         @project = project
       end
 
@@ -16,9 +17,8 @@ module Projects
 
       # Possible return values: Clusters::KnativeServicesFinder::KNATIVE_STATE
       def knative_installed
-        states = @clusters.map do |cluster|
-          cluster.application_knative
-          cluster.knative_services_finder(project).knative_detected.tap do |state|
+        states = services_finders.map do |finder|
+          finder.knative_detected.tap do |state|
             return state if state == ::Clusters::KnativeServicesFinder::KNATIVE_STATES['checking'] # rubocop:disable Cop/AvoidReturnFromBlocks
           end
         end
@@ -31,66 +31,70 @@ module Projects
       end
 
       def invocation_metrics(environment_scope, name)
-        return unless prometheus_adapter&.can_query?
+        environment = finders_for_scope(environment_scope).first&.environment
 
-        cluster = @clusters.find do |c|
-          environment_scope == c.environment_scope
+        if environment.present? && environment.prometheus_adapter&.can_query?
+          func = ::Serverless::Function.new(project, name, environment.deployment_namespace)
+          environment.prometheus_adapter.query(:knative_invocation, func)
         end
-
-        func = ::Serverless::Function.new(project, name, cluster.kubernetes_namespace_for(project))
-        prometheus_adapter.query(:knative_invocation, func)
       end
 
       def has_prometheus?(environment_scope)
-        @clusters.any? do |cluster|
-          environment_scope == cluster.environment_scope && cluster.application_prometheus_available?
+        finders_for_scope(environment_scope).any? do |finder|
+          finder.cluster.application_prometheus_available?
         end
       end
 
       private
 
       def knative_service(environment_scope, name)
-        @clusters.map do |cluster|
-          next if environment_scope != cluster.environment_scope
-
-          services = cluster
-            .knative_services_finder(project)
+        finders_for_scope(environment_scope).map do |finder|
+          services = finder
             .services
             .select { |svc| svc["metadata"]["name"] == name }
 
-          add_metadata(cluster, services).first unless services.nil?
+          add_metadata(finder, services).first unless services.nil?
         end
       end
 
       def knative_services
-        @clusters.map do |cluster|
-          services = cluster
-            .knative_services_finder(project)
-            .services
+        services_finders.map do |finder|
+          services = finder.services
 
-          add_metadata(cluster, services) unless services.nil?
+          add_metadata(finder, services) unless services.nil?
         end
       end
 
-      def add_metadata(cluster, services)
+      def add_metadata(finder, services)
+        add_pod_count = services.one?
+
         services.each do |s|
-          s["environment_scope"] = cluster.environment_scope
-          s["cluster_id"] = cluster.id
+          s["environment_scope"] = finder.cluster.environment_scope
+          s["cluster_id"] = finder.cluster.id
 
-          if services.length == 1
-            s["podcount"] = cluster
-              .knative_services_finder(project)
+          if add_pod_count
+            s["podcount"] = finder
               .service_pod_details(s["metadata"]["name"])
               .length
           end
         end
       end
 
-      # rubocop: disable CodeReuse/ServiceClass
-      def prometheus_adapter
-        @prometheus_adapter ||= ::Prometheus::AdapterService.new(project).prometheus_adapter
+      def services_finders
+        strong_memoize(:services_finders) do
+          available_environments.map(&:knative_services_finder).compact
+        end
+      end
+
+      def available_environments
+        @project.environments.available.preload_cluster
+      end
+
+      def finders_for_scope(environment_scope)
+        services_finders.select do |finder|
+          environment_scope == finder.cluster.environment_scope
+        end
       end
-      # rubocop: enable CodeReuse/ServiceClass
     end
   end
 end