Protect against rolling back to a bad version

lib/mrsk/commands/app.rb

@@ -93,11 +93,21 @@ class Mrsk::Commands::App < Mrsk::Commands::Base
       "head -n 1"
   end
 
+  def all_versions_from_available_containers
+    pipe \
+      docker(:image, :ls, "--format", '"{{.Tag}}"', config.repository),
+      "head -n 1"
+  end
+
 
   def list_containers
     docker :container, :ls, "-a", *service_filter
   end
 
+  def list_container_names
+    [ *list_containers, "--format", "'{{ .Names }}'" ]
+  end
+
   def remove_container(version:)
     pipe \
       container_id_for(container_name: service_with_version(version)),