standalone.exs: Ensure OTP version (#987)

mix.exs

@@ -2,10 +2,12 @@ defmodule Livebook.MixProject do
   use Mix.Project
 
   @elixir_requirement "~> 1.13"
-  @app_elixir_version "1.13.2"
   @version "0.5.2"
   @description "Interactive and collaborative code notebooks - made with Phoenix LiveView"
 
+  @app_elixir_version "1.13.2"
+  @app_otp_version "24.2"
+
   def project do
     [
       app: :livebook,
@@ -155,7 +157,7 @@ defmodule Livebook.MixProject do
     Code.require_file("rel/app/standalone.exs")
 
     release
-    |> Standalone.copy_erlang()
+    |> Standalone.copy_otp(@app_otp_version)
     |> Standalone.copy_elixir(@app_elixir_version)
   end
 

rel/app/standalone.exs

@@ -3,10 +3,16 @@ defmodule Standalone do
   require Logger
 
   @doc """
-  Copies ERTS into the release.
+  Copies OTP into the release.
   """
-  @spec copy_erlang(Mix.Release.t()) :: Mix.Release.t()
-  def copy_erlang(release) do
+  @spec copy_otp(Mix.Release.t(), otp_version :: String.t()) :: Mix.Release.t()
+  def copy_otp(release, otp_version) do
+    expected_otp_version = otp_version()
+
+    if otp_version != expected_otp_version do
+      raise "expected OTP #{expected_otp_version}, got: #{otp_version}"
+    end
+
     {erts_source, erts_bin_dir, erts_lib_dir, _erts_version} = erts_data()
 
     erts_destination_source = Path.join(release.path, "vendor/bin")
@@ -35,6 +41,7 @@ defmodule Standalone do
     export PROGNAME
     exec "$BINDIR/erlexec" ${1+"$@"}
     """)
+
     executable!(Path.join(erts_destination_source, "erl"))
 
     # Copy lib
@@ -45,9 +52,13 @@ defmodule Standalone do
     |> File.cp_r!(erts_destination_lib, fn _, _ -> false end)
 
     # copy *.boot files to <resource_path>/bin
-    erts_destination_bin =  Path.join(release.path, "bin")
+    erts_destination_bin = Path.join(release.path, "bin")
 
-    boot_files = erts_bin_dir |> Path.join("*.boot") |> Path.wildcard() |> Enum.map(& String.split(&1, "/") |> List.last())
+    boot_files =
+      erts_bin_dir
+      |> Path.join("*.boot")
+      |> Path.wildcard()
+      |> Enum.map(&(String.split(&1, "/") |> List.last()))
 
     File.mkdir_p!(erts_destination_bin)
 
@@ -58,18 +69,32 @@ defmodule Standalone do
     %{release | erts_source: erts_source}
   end
 
+  # From https://github.com/fishcakez/dialyze/blob/6698ae582c77940ee10b4babe4adeff22f1b7779/lib/mix/tasks/dialyze.ex#L168
+  defp otp_version do
+    major = :erlang.system_info(:otp_release) |> List.to_string()
+    vsn_file = Path.join([:code.root_dir(), "releases", major, "OTP_VERSION"])
+
+    try do
+      {:ok, contents} = File.read(vsn_file)
+      String.split(contents, "\n", trim: true)
+    else
+      [full] -> full
+      _ -> major
+    catch
+      :error, _ -> major
+    end
+  end
+
   @doc """
-  Copies elixir into the release.
+  Copies Elixir into the release.
   """
   @spec copy_elixir(Mix.Release.t(), elixir_version :: String.t()) :: Mix.Release.t()
   def copy_elixir(release, elixir_version) do
-    # download and unzip
     standalone_destination = Path.join(release.path, "vendor/elixir")
     download_elixir_at_destination(standalone_destination, elixir_version)
 
-    # make executable
     ["elixir", "elixirc", "mix", "iex"]
-    |> Enum.map(&(executable!(Path.join(standalone_destination, "bin/#{&1}"))))
+    |> Enum.map(&executable!(Path.join(standalone_destination, "bin/#{&1}")))
 
     release
   end
@@ -83,20 +108,22 @@ defmodule Standalone do
 
   defp erts_data do
     version = :erlang.system_info(:version)
-    {:filename.join(:code.root_dir(), 'erts-#{version}'), :filename.join(:code.root_dir(), 'bin'), :code.lib_dir(), version}
+
+    {:filename.join(:code.root_dir(), 'erts-#{version}'), :filename.join(:code.root_dir(), 'bin'),
+     :code.lib_dir(), version}
   end
 
   defp fetch_body!(url) do
-    Logger.debug("Downloading elixir from #{url}")
-    case Livebook.Utils.HTTP.request(:get, url, [timeout: :infinity]) do
+    Logger.debug("Downloading Elixir from #{url}")
+
+    case Livebook.Utils.HTTP.request(:get, url, timeout: :infinity) do
       {:ok, 200, _headers, body} ->
         body
 
-      {:error, error}  ->
+      {:error, error} ->
         raise "couldn't fetch #{url}: #{inspect(error)}"
     end
   end
 
   defp executable!(path), do: File.chmod!(path, 0o755)
-
 end