add Docker support with distroless Nix image

- Add docker package to flake.nix using buildLayeredImage
- Creates 73MB distroless image with Node.js + jellarr bundle
- Add docker-compose.yml example following configarr pattern
- Image uses config/config.yml as default path
- Tested successfully with podman

Users can build locally with: nix build .#docker && docker load < result
Or use published image: ghcr.io/venkyr77/jellarr:latest (coming soon)

docker-compose.yml

@@ -0,0 +1,10 @@
+services:
+  jellarr:
+    image: ghcr.io/venkyr77/jellarr:latest
+    container_name: jellarr
+    environment:
+      - JELLARR_API_KEY=${JELLARR_API_KEY}
+      - TZ=Etc/UTC
+    volumes:
+      - ./config:/config
+    restart: "no"

flake.nix

@@ -40,9 +40,27 @@
 
         formatter = (treefmt-nix.lib.evalModule pkgs ./treefmt.nix).config.build.wrapper;
 
-        packages.default = import ./nix/package.nix {
-          inherit pkgs;
-          inherit (pkgs) lib;
+        packages = {
+          default = import ./nix/package.nix {
+            inherit pkgs;
+            inherit (pkgs) lib;
+          };
+
+          docker = pkgs.dockerTools.buildLayeredImage {
+            name = "jellarr";
+            tag = "latest";
+
+            contents = [
+              pkgs.coreutils
+              pkgs.nodejs_24
+              config.packages.default
+            ];
+
+            config = {
+              Cmd = ["${pkgs.lib.getExe config.packages.default}"];
+              Env = ["NODE_ENV=production"];
+            };
+          };
         };
       };
     };