Failed save to database

Hello!
Git Repository here.
I have a problem with saving data to database. I use mongodb_ecto adapter, when I try save it through iex console I can do it:

iex(1)> Friends.PersonController.save()
START SAVING
SAVED

09:58:17.706 [debug] QUERY OK db=0.4ms
INSERT coll="people" document=[age: 11, _id: #BSON.ObjectId<5b027c190d1a8f0f042d5600>] []
:ok

or

iex(1)> person = %Friends.Person{}
%Friends.Person{
  __meta__: #Ecto.Schema.Metadata<:built, "people">,
  age: nil,
  first_name: nil,
  id: nil,
  last_name: nil
}
iex(2)> Friends.Repo.insert(person)

10:50:43.451 [debug] QUERY OK db=0.4ms
INSERT coll="people" document=[_id: #BSON.ObjectId<5b0288630d1a8f06ef2e3699>] []
{:ok,
 %Friends.Person{
   __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
   age: nil,
   first_name: nil,
   id: "5b0288630d1a8f06ef2e3699",
   last_name: nil
 }}

But if uncomment Friends.PersonController.save and try to call it when program is work, I got error:

⇒ mix
Compiling 1 file (.ex)
START SAVING

== Compilation error in file lib/friends.ex ==
** (ArgumentError) argument error
    (stdlib) :ets.lookup_element(Mongo.IdServer, :machineprocid, 2)
    lib/mongo/id_server.ex:50: Mongo.IdServer.new/0
    lib/ecto/repo/schema.ex:651: Ecto.Repo.Schema.autogenerate_id/4
    lib/ecto/repo/schema.ex:199: anonymous fn/13 in Ecto.Repo.Schema.do_insert/4
    lib/friends/person_controller.ex:11: Friends.PersonController.save/0
    lib/friends.ex:4: (module)

What’s the solution for it? How I can do it?
I have an assumption that when I run the program, I just do not start Mongo?