# `Nerves.Package.Platform`
[🔗](https://github.com/nerves-project/nerves/blob/v1.15.1/lib/nerves/package/platform.ex#L6)

Defines the Nerves package platform behaviour

This behaviour is implemented on a module that would be used to construct
an artifact for a nerves package. Nerves packages are prioritized to be
compiled before any other dependencies, therefore, a package platform
is useful for constructing host tools to be used during the elixir compile
phase.

Here is a simple example that touches a file in the `Artifact.build_path`

```elixir
defmodule SystemPlatform do
  @behaviour Nerves.Artifact.BuildRunner
  @behaviour Nerves.Package.Platform

  def bootstrap(_pkg) do
    System.put_env("NERVES_BOOTSTRAP_SYSTEM", "1")
    :ok
  end

  def build(pkg, _toolchain, _opts) do
    build_path = Artifact.build_path(pkg)
    File.rm_rf!(build_path)
    File.mkdir_p!(build_path)

    build_path
    |> Path.join("file")
    |> File.touch()

    {:ok, build_path}
  end

  def build_path_link(pkg) do
    Artifact.build_path(pkg)
  end

  def archive(pkg, _toolchain, _opts) do
    build_path = Artifact.build_path(pkg)
    name = Artifact.download_name(pkg) <> Artifact.ext(pkg)
    Nerves.Utils.File.tar(build_path, name)
    {:ok, Path.join(File.cwd!, name)}
  end

  def clean(pkg) do
    Artifact.build_path(pkg)
    |> File.rm_rf()
  end
end

```

# `bootstrap`

```elixir
@callback bootstrap(Nerves.Package.t()) :: :ok | {:error, error :: term()}
```

 Bootstrap is called as the final phase of loading the Nerves environment.
 It is used typically for setting / unsetting any system environment
 variables. For example, if we were building a C cross compiler, we would
 use the bootstrap phase to override CC to point to our compiler.

# `build_path_link`

```elixir
@callback build_path_link(package :: Nerves.Package.t()) :: build_path_link :: String.t()
```

Build path link should return the location inside the `Artifact.build_path`
that represents the final artifact. This is used to symlink the global
artifact to the local build_path location.

---

*Consult [api-reference.md](api-reference.md) for complete listing*