View Source Rustler (Rustler v0.32.1)

Provides compile-time configuration for a NIF module.

When used, Rustler expects the :otp_app as option. The :otp_app should point to the OTP application that the dynamic library can be loaded from.

For example:

defmodule MyNIF do
  use Rustler, otp_app: :my_nif

This allows the module to be configured like so:

config :my_nif, MyNIF,
  crate: :my_nif,
  load_data: [1, 2, 3]

Configuration options

  • :cargo - Specify how to envoke the rust compiler. Options are:

    • :system (default) - use cargo from the system (must be in $PATH)
    • {:system, <channel>} - use cargo from the system with the given channel. Specified as a string, passed directly to cargo (e.g. "+nightly").
    • {:rustup, <version>} - use rustup to specify which channel to use. Available options include: :stable, :beta, :nightly, or a string which specifies a specific version (e.g. "1.39.0").
    • {:bin, "/path/to/binary"} - provide a specific path to cargo.
  • :crate - the name of the Rust crate, if different from your otp_app value. If you have more than one crate in your project, you will need to be explicit about which crate you intend to use.

  • :default_features - a boolean to specify whether the crate's default features should be used.

  • :env - Specify a list of environment variables when envoking the compiler.

  • :features - a list of features to enable when compiling the crate.

  • :load_data - Any valid term. This value is passed into the NIF when it is loaded (default: 0)

  • :load_data_fun - {Module, :function} to dynamically generate load_data. Default value: nil.

    This parameter is mutually exclusive with load_data which means that load_data has to be set to it's default value.


    defmodule NIF do
      use Rustler, load_data_fun: {Deployment, :nif_data}
    defmodule Deployment do
      def nif_data do
        :code.priv_dir(:otp_app) |> IO.iodata_to_binary()
  • :load_from - This option allows control over where the final artifact should be loaded from at runtime. By default the compiled artifact is loaded from the owning :otp_app's priv/native directory. This option comes in handy in combination with the :skip_compilation? option in order to load pre-compiled artifacts. To override the default behaviour specify a tuple: {:my_app, "priv/native/<artifact>"}. Due to the way :erlang.load_nif/2 works, the artifact should not include the file extension (i.e. .so, .dll).

  • :mode - Specify which mode to compile the crate with (default: :release)

  • :path - By default, rustler expects the crate to be found in native/<crate> in the root of the project. Use this option to override this.

  • :skip_compilation? - This option skips envoking the rust compiler. Specify this option in combination with :load_from to load a pre-compiled artifact.

  • :target - Specify a compile target triple.

  • :target_dir - Override the compiler output directory.

Any of the above options can be passed directly into the use macro like so:

defmodule MyNIF do
  use Rustler,
    otp_app: :my_nif,
    crate: :some_other_crate,
    load_data: :something



Supported NIF API versions.


Supported NIF API versions.