add nix flake

.github/workflows/nix.yml

@@ -0,0 +1,50 @@
+name: Nix
+
+on:
+  pull_request:
+    branches: ['**', '!update/**', '!pr/**']
+    paths:
+      - 'flake.nix'
+      - 'flake.lock'
+      - '.github/workflows/nix.yml'
+  push:
+    branches: ['**', '!update/**', '!pr/**']
+    tags: [v*]
+    paths:
+      - 'flake.nix'
+      - 'flake.lock'
+      - '.github/workflows/nix.yml'
+
+concurrency:
+  group: nix @ ${{ github.workflow }} @ ${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  flake-check:
+    name: Build & smoke test
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - ubuntu-24.04-arm
+          - macos-latest
+    runs-on: ${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: cachix/install-nix-action@v31
+        with:
+          extra_nix_config: |
+            experimental-features = nix-command flakes
+
+      - name: Check flake
+        run: nix flake check -L
+
+      - name: Build dumbo package
+        run: nix build .#dumbo -L
+
+      - name: Smoke test binary
+        run: |
+          ./result/bin/dumbo -v
+          ./result/bin/dumbo help

flake.nix

@@ -0,0 +1,103 @@
+{
+  description = "dumbo - a Flyway compatible database migration tool for Postgres";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs =
+    { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (
+      system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+
+        version = "0.10.2";
+
+        # Release assets from https://github.com/rolang/dumbo/releases
+        # Update `version` and these hashes together when bumping.
+        # Get a hash with: nix-prefetch-url --type sha256 <asset-url>
+        assets = {
+          x86_64-linux = {
+            asset = "dumbo-cli-x86_64-linux";
+            sha256 = "0pkligx760csm9mmbdl2mq3abhn1ib8jl6rilgh6x7hxa6j07m18";
+          };
+          aarch64-linux = {
+            asset = "dumbo-cli-aarch64-linux";
+            sha256 = "0rgsg8a52h3q57d460kb6bzv1wm4v5rcb7y0qzxw1lh57qp96q5h";
+          };
+          aarch64-darwin = {
+            asset = "dumbo-cli-aarch64-macosx";
+            sha256 = "1f2ns0glccw0zb2w21fwsl81xmqa4a7qdqv0adwypbpbxvkcx1r2";
+          };
+        };
+
+        asset = assets.${system} or (throw "dumbo: no release binary for system '${system}'");
+
+        dumbo = pkgs.stdenv.mkDerivation {
+          pname = "dumbo";
+          inherit version;
+
+          src = pkgs.fetchurl {
+            url = "https://github.com/rolang/dumbo/releases/download/v${version}/${asset.asset}";
+            sha256 = asset.sha256;
+          };
+
+          dontUnpack = true;
+          dontBuild = true;
+          dontStrip = true; # scala-native binaries aren't stdenv-built ELF/Mach-O, avoid re-stripping surprises
+
+          nativeBuildInputs = pkgs.lib.optionals pkgs.stdenv.hostPlatform.isLinux [ pkgs.autoPatchelfHook ]
+            ++ pkgs.lib.optionals pkgs.stdenv.hostPlatform.isDarwin [ pkgs.makeWrapper ];
+
+          buildInputs = pkgs.lib.optionals pkgs.stdenv.hostPlatform.isLinux [
+            pkgs.s2n-tls
+            pkgs.utf8proc
+            pkgs.openssl
+            pkgs.zlib
+            pkgs.stdenv.cc.cc.lib
+          ];
+
+          installPhase = ''
+            runHook preInstall
+            install -Dm755 "$src" "$out/bin/dumbo"
+            runHook postInstall
+          '';
+
+          # The macOS release binary is dynamically linked against Homebrew's
+          # absolute install paths (/opt/homebrew/opt/...), which don't exist
+          # in the Nix sandbox. It wasn't linked with -headerpad_max_install_names,
+          # so `install_name_tool -change`/`-add_rpath` fail ("larger updated
+          # load commands do not fit") since nixpkgs store paths are longer
+          # than the original Homebrew ones. Rather than rewriting load
+          # commands (which would also invalidate the binary's code
+          # signature), wrap it so dyld falls back to the nixpkgs libs when
+          # the hardcoded Homebrew paths can't be found.
+          postFixup = pkgs.lib.optionalString pkgs.stdenv.hostPlatform.isDarwin ''
+            wrapProgram "$out/bin/dumbo" \
+              --set DYLD_FALLBACK_LIBRARY_PATH "${pkgs.lib.makeLibraryPath [
+                pkgs.s2n-tls
+                pkgs.utf8proc
+                pkgs.openssl
+              ]}"
+          '';
+
+          meta = {
+            description = "Flyway compatible database migration tool for Postgres";
+            homepage = "https://github.com/rolang/dumbo";
+            license = pkgs.lib.licenses.mit;
+            platforms = builtins.attrNames assets;
+            mainProgram = "dumbo";
+            sourceProvenance = [ pkgs.lib.sourceTypes.binaryNativeCode ];
+          };
+        };
+      in
+      {
+        packages.default = dumbo;
+        packages.dumbo = dumbo;
+
+        apps.default = flake-utils.lib.mkApp { drv = dumbo; };
+      }
+    );
+}