initial backend nix build - get jar

flake.nix

@@ -2,12 +2,17 @@
   description = "Planning Poker web app. Trying to build something and learn new things";
   inputs.nixpkgs.url = "github:nixos/nixpkgs";
   inputs.flake-utils.url = "github:numtide/flake-utils";
+  inputs.sbt-derivation.url = "github:zaninime/sbt-derivation/master";
+  inputs.sbt-derivation.inputs.nixpkgs.follows = "nixpkgs";
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, sbt-derivation }:
     flake-utils.lib.eachDefaultSystem
       (system:
-        let pkgs = nixpkgs.legacyPackages.${system}; in
-        {
+        let
+          pkgs = nixpkgs.legacyPackages.${system};
+          packageName = "blanning-poker-grargh";
+          version = "0.1.1";
+        in {
           devShells.default = pkgs.mkShell {
             buildInputs = [
               pkgs.nodejs
@@ -21,6 +26,22 @@
               echo "dev env for planning poker BWARGH started"
             '';
           };
+          packages.backend = sbt-derivation.lib.mkSbtDerivation rec {
+            inherit pkgs version;
+
+            # ...and the rest of the arguments
+            pname = "${packageName}-backend";
+            depsSha256 = "sha256-UOEq6KFS4rh4eaKxnRcVOh4SQWn3hnfpzcyRqPnFvco=";
+            src = pkgs.nix-gitignore.gitignoreSource [] ./.;
+            buildPhase = ''
+              sbt backend/assembly
+            '';
+            installPhase = ''
+              mkdir -p $out/bin
+              cp backend/target/scala-*/backend-assembly-*.jar $out/bin/
+            '';
+
+          };
         }
       );
   # see https://serokell.io/blog/practical-nix-flakes