fix: nix build (#247)

flake.nix

@@ -59,7 +59,7 @@
             mixFodDeps = beamPackages.fetchMixDeps {
               inherit src version;
               pname = "${pname}-deps";
-              hash = "sha256-jUkz/pu3iyizpHkMYgmbYfalFv10t11b6SmLVEXAJ30=";
+              hash = "sha256-sRve0L7qFw5vEsespIXVg4loSej+oLO1ewdmT6qGExw=";
             };
 
             preConfigure = ''
@@ -73,6 +73,10 @@
               export PATH="$bindir:$PATH"
             '';
 
+            preBuild = ''
+              export BURRITO_ERTS_PATH=${beamPackages.erlang}/lib/erlang
+            '';
+
             preInstall =
               if type == "local" then ''
                 export BURRITO_TARGET="${burritoExe(system)}"

mix.exs

@@ -40,15 +40,15 @@ defmodule NextLS.MixProject do
       next_ls: [
         steps: [:assemble, &Burrito.wrap/1],
         burrito: [
-          targets: [
+          targets: inject_custom_erts([
             darwin_arm64: [os: :darwin, cpu: :aarch64],
             darwin_amd64: [os: :darwin, cpu: :x86_64],
             linux_arm64: [os: :linux, cpu: :aarch64, libc: :gnu],
             linux_amd64: [os: :linux, cpu: :x86_64, libc: :gnu],
             linux_arm64_musl: [os: :linux, cpu: :aarch64, libc: :musl],
             linux_amd64_musl: [os: :linux, cpu: :x86_64, libc: :musl],
             windows_amd64: [os: :windows, cpu: :x86_64]
-          ]
+          ])
         ]
       ]
     ]
@@ -84,4 +84,19 @@ defmodule NextLS.MixProject do
       files: ~w(lib LICENSE mix.exs priv README.md .formatter.exs)
     ]
   end
+
+  defp inject_custom_erts(targets) do
+    # By default, Burrito downloads ERTS from https://burrito-otp.b-cdn.net.
+    # When building with Nix, side-effects like network access are not allowed,
+    # so we need to inject our own ERTS path.
+
+    erts_path = System.get_env("BURRITO_ERTS_PATH", "")
+
+    Enum.map(targets, fn {target_name, target_conf} ->
+      case erts_path do
+        "" -> {target_name, target_conf}
+        path -> {target_name, [{:custom_erts, path} | target_conf]}
+      end
+    end)
+  end
 end

mix.lock

@@ -1,5 +1,5 @@
 %{
-  "burrito": {:git, "https://github.com/burrito-elixir/burrito.git", "5c7b29811279f3272005534a3fec29a687e9b6bf", []},
+  "burrito": {:git, "https://github.com/burrito-elixir/burrito.git", "a86857636eaba9a7fa179fd970ed6cf82e9e7d59", []},
   "bypass": {:hex, :bypass, "2.1.0", "909782781bf8e20ee86a9cabde36b259d44af8b9f38756173e8f5e2e1fabb9b1", [:mix], [{:plug, "~> 1.7", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 2.0", [hex: :plug_cowboy, repo: "hexpm", optional: false]}, {:ranch, "~> 1.3", [hex: :ranch, repo: "hexpm", optional: false]}], "hexpm", "d9b5df8fa5b7a6efa08384e9bbecfe4ce61c77d28a4282f79e02f1ef78d96b80"},
   "castore": {:hex, :castore, "1.0.3", "7130ba6d24c8424014194676d608cb989f62ef8039efd50ff4b3f33286d06db8", [:mix], [], "hexpm", "680ab01ef5d15b161ed6a95449fac5c6b8f60055677a8e79acf01b27baa4390b"},
   "cc_precompiler": {:hex, :cc_precompiler, "0.1.8", "933a5f4da3b19ee56539a076076ce4d7716d64efc8db46fd066996a7e46e2bfd", [:mix], [{:elixir_make, "~> 0.7.3", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm", "176bdf4366956e456bf761b54ad70bc4103d0269ca9558fd7cee93d1b3f116db"},