Added nix flake for building the mos cli tool

flake.nix

@@ -0,0 +1,98 @@
+{
+  description = "Mongoose OS command line tool";
+
+  # Nixpkgs / NixOS version to use.
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+
+  outputs = { self, nixpkgs }:
+    let
+
+      # to work with older version of flakes
+      lastModifiedDate = self.lastModifiedDate or self.lastModified or "19700101";
+
+      # Generate a user-friendly version number.
+      version = builtins.substring 0 8 lastModifiedDate;
+
+      # System types to support.
+      supportedSystems = [ "x86_64-linux" "x86_64-darwin" "aarch64-linux" "aarch64-darwin" ];
+
+      # Helper function to generate an attrset '{ x86_64-linux = f "x86_64-linux"; ... }'.
+      forAllSystems = nixpkgs.lib.genAttrs supportedSystems;
+
+      # Nixpkgs instantiated for supported system types.
+      nixpkgsFor = forAllSystems (system: import nixpkgs { inherit system; });
+
+    in
+    {
+
+      # Provide some binary packages for selected system types.
+      packages = forAllSystems (system:
+        let
+          pkgs = nixpkgsFor.${system};
+        in
+        {
+          default = pkgs.buildGoModule {
+            pname = "mos";
+            inherit version;
+            # In 'nix develop', we don't need a copy of the source tree
+            # in the Nix store.
+            src = ./.;
+
+            # This hash locks the dependencies of this package. It is
+            # necessary because of how Go requires network access to resolve
+            # VCS.  See https://www.tweag.io/blog/2021-03-04-gomod2nix/ for
+            # details. Normally one can build with a fake hash and rely on native Go
+            # mechanisms to tell you what the hash should be or determine what
+            # it should be "out-of-band" with other tooling (eg. gomod2nix).
+            # To begin with it is recommended to set this, but one must
+            # remember to bump this hash when your dependencies change.
+            # vendorHash = pkgs.lib.fakeHash;
+
+            vendorHash = "sha256-PpzclrsG7HYwbowGCbMQFj6+/w+svyMzkxYh2VpR18Y=";
+
+            preBuild = ''
+              echo "package version
+              const (
+                Version = \"${version}\"
+                BuildId = \"${self.rev or self.dirtyRev}\"
+                BuildTimestamp = \"${lastModifiedDate}\"
+              )" > version/version.go
+            '';
+
+            nativeBuildInputs = with pkgs; [ pkg-config ];
+
+            buildInputs = with pkgs; [ libusb1 libftdi1 ];
+          };
+        });
+
+      apps = forAllSystems (system: {
+          default = {
+            type = "app";
+            program = "${self.packages.${system}.default}/bin/cli";
+          };
+          instance = {
+            type = "app";
+            program = "${self.packages.${system}.default}/bin/instance";
+          };
+          manager = {
+            type = "app";
+            program = "${self.packages.${system}.default}/bin/manager";
+          };
+        }
+      );
+
+      # Add dependencies that are only needed for development
+      devShells = forAllSystems (system:
+        let
+          pkgs = nixpkgsFor.${system};
+        in
+        {
+          default = pkgs.mkShell {
+            buildInputs = [ self.packages.${system}.default pkgs.esptool ];
+            shellHook = ''
+              alias mos=cli
+            '';
+          };
+        });
+    };
+}