Introduce flake.nix for project to build for NixOS (#387)

flake.lock

@@ -0,0 +1,93 @@
+{
+  "nodes": {
+    "naersk": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      },
+      "locked": {
+        "lastModified": 1718727675,
+        "narHash": "sha256-uFsCwWYI2pUpt0awahSBorDUrUfBhaAiyz+BPTS2MHk=",
+        "owner": "nix-community",
+        "repo": "naersk",
+        "rev": "941ce6dc38762a7cfb90b5add223d584feed299b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "naersk",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 0,
+        "narHash": "sha256-US1tAChvPxT52RV8GksWZS415tTS7PV42KTc2PNDBmc=",
+        "path": "/nix/store/aa0zsahvyqnvzkicsh29jirm9hwv95pg-source",
+        "type": "path"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
+        "lastModified": 1720244366,
+        "narHash": "sha256-WrDV0FPMVd2Sq9hkR5LNHudS3OSMmUrs90JUTN+MXpA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "49ee0e94463abada1de470c9c07bfc12b36dcf40",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-24.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1718428119,
+        "narHash": "sha256-WdWDpNaq6u1IPtxtYHHWpl5BmabtpmLnMAx0RdJ/vo8=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e6cea36f83499eb4e9cd184c8a8e823296b50ad5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "naersk": "naersk",
+        "nixpkgs": "nixpkgs_2",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1720318855,
+        "narHash": "sha256-w3CCVK9LJ5aznXGkO1IyAlbvMNJfyA+dBF7Z1Zwx1LA=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "3eed08a074cd2000884a69d448d70da2843f7103",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,57 @@
+# This flake was initially generated by fh, the CLI for FlakeHub (version 0.1.12)
+{
+  # Flake inputs
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-24.05";
+    naersk.url = "github:nix-community/naersk";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+  };
+
+  # Flake outputs that other flakes can use
+  outputs = {
+    self,
+    nixpkgs,
+    naersk,
+    rust-overlay,
+  }: let
+    supportedSystems = ["x86_64-linux" "aarch64-linux"];
+    forEachSupportedSystem = f:
+      nixpkgs.lib.genAttrs supportedSystems (system:
+        f rec {
+          pkgs = import nixpkgs {
+            inherit system;
+            overlays = [rust-overlay.overlays.default];
+          };
+          naersk' = pkgs.callPackage naersk {};
+        });
+  in {
+    packages = forEachSupportedSystem ({
+      pkgs,
+      naersk',
+    }: {
+      default = naersk'.buildPackage {
+        src = ./.;
+        nativeBuildInputs = with pkgs; [
+          perl
+          jq
+          openconnect
+          libsoup
+          webkitgtk
+          pkg-config
+        ];
+
+        overrideMain = {...}: {
+          postPatch  = ''
+            substituteInPlace crates/gpapi/src/lib.rs \
+              --replace-fail /usr/bin/gpclient $out/bin/gpclient \
+              --replace-fail /usr/bin/gpservice $out/bin/gpservice \
+              --replace-fail /usr/bin/gpgui-helper $out/bin/gpgui-helper \
+              --replace-fail /usr/bin/gpgui $out/bin/gpgui \
+              --replace-fail /usr/bin/gpauth $out/bin/gpauth
+          '';
+        };
+
+      };
+    });
+  };
+}