let db_connection caqti_switch : (unit, Caqti_miou.connection) Vifu.Device.device
    =
  let f () =
    let db_uri = Config.Exchangedb_postgres.config in
    match Caqti_miou_unix.connect ~sw:caqti_switch db_uri with
    | Error err ->
        Fmt.failwith "Database connection failure: %a." Caqti_error.pp err
    | Ok conn -> (
        match Pg.preflight conn with
        | Error err ->
            Fmt.failwith "Database preflight failure: %a." Caqti_error.pp err
        | Ok () ->
            Logs.info (fun m -> m "database connection initialized");
            conn)
  in
  let finally (module Conn : Caqti_miou.CONNECTION) = Conn.disconnect () in
  Vifu.Device.v ~name:"db_connection" ~finally [] f

let keys storage =
  let f (module Conn : Pg.CONN) () =
    let (module Fs) =
      (module struct
        let t = storage
      end)
    in
    let keys : (module Keys.S) = (module Keys.Make (Conn) (Fs)) in
    keys
  in
  let finally _key = () in
  Vifu.Device.v ~name:"keys" ~finally [ Vifu.Device.value db_connection ] f