ensure monitoring manager deletion and creation on endpoint update

app/models/endpoint.rb

@@ -9,6 +9,19 @@ class Endpoint < ApplicationRecord
   validates :url, :uniqueness => true, :if => :url
   validate :validate_certificate_authority
 
+  after_create  :endpoint_created
+  after_destroy :endpoint_destroyed
+
+  def endpoint_created
+    # Make sure monitoring manager is created for the prometheus endpoint
+    resource.endpoint_created(role) if resource.respond_to?(:endpoint_created)
+  end
+
+  def endpoint_destroyed
+    # Make sure monitoring manager is delete for the prometheus endpoint
+    resource.endpoint_destroyed(role) if resource.respond_to?(:endpoint_destroyed)
+  end
+
   def verify_ssl=(val)
     val = resolve_verify_ssl_value(val)
     super

app/models/mixins/has_monitoring_manager_mixin.rb

@@ -1,21 +1,30 @@
 module HasMonitoringManagerMixin
   extend ActiveSupport::Concern
 
-  private
+  def endpoint_created(role)
+    if role == "prometheus_alerts" && monitoring_manager.nil?
+      monitoring_manager = ensure_monitoring_manager
+      monitoring_manager.save
+    end
+  end
 
-  def ensure_monitoring_manager
-    # monitoring_manager should be defined by child classes.
-    if try(:monitoring_manager_needed?)
-      build_monitoring_manager(:parent_manager => self)
-      monitoring_manager.name = "#{name} Monitoring Manager"
+  def endpoint_destroyed(role)
+    if role == "prometheus_alerts" && monitoring_manager.present?
+      # TODO: if someone deletes the alerts endpoint and then quickly readds it they can end up without a manager.
+      monitoring_manager.destroy_queue
     end
-    ensure_monitoring_manager_properties
   end
 
-  def ensure_monitoring_manager_properties
-    if monitoring_manager
-      monitoring_manager.zone_id = zone_id
-      monitoring_manager.provider_region = provider_region
+  private
+
+  def ensure_monitoring_manager
+    if monitoring_manager.nil?
+      build_monitoring_manager(:parent_manager  => self,
+                               :name            => "#{name} Monitoring Manager",
+                               :zone_id         => zone_id,
+                               :provider_region => provider_region)
     end
+
+    monitoring_manager
   end
 end