feat: Add nix/flake support (#3743)

* CI update - Ubuntu Image

* Add nix/flake support

Example:

nix build github:mimblewimble/grin

./result/bin/grin --help

* Ignore ./result in git repo

result is the default symlink output for nix build

---------

Co-authored-by: chives101 <chives101@users.noreply.github.com>

.gitignore

@@ -14,3 +14,4 @@ wallet/db
 .idea/
 .vscode/
 /node*
+result

azure-pipelines.yml

@@ -31,7 +31,7 @@ variables:
 jobs:
 - job: linux
   pool:
-    vmImage: ubuntu-18.04
+    vmImage: ubuntu-22.04
   strategy:
     matrix:
       servers:

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1681411673,
+        "narHash": "sha256-23S0skJVstbQtrhy+65Bi4Jrdw74hY1OYbBnuuQausc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "80d54821fffaffbc90409a1262ea91071e0dff8f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "release-22.11",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,46 @@
+{
+  description = "THE MIMBLEWIMBLE BLOCKCHAIN.";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/release-22.11";
+  };
+
+  outputs = { self, nixpkgs, }:
+    let
+      forAllSystems = with nixpkgs;
+        lib.genAttrs lib.systems.flakeExposed;
+
+      nixpkgsFor = forAllSystems (system: import nixpkgs
+        { inherit system; overlays = [ self.overlay ]; }
+      );
+    in
+    {
+      overlay = final: prev:
+        with final;
+        {
+          grin = pkgs.rustPlatform.buildRustPackage {
+            pname = "grin";
+            version = "5.2.0-alpha.2";
+            src = ./.;
+
+            cargoLock = {
+              lockFile = ./Cargo.lock;
+            };
+
+            nativeBuildInputs = [ pkgs.llvmPackages_latest.clang ];
+            buildInputs = [ pkgs.ncurses ];
+            LIBCLANG_PATH =
+              "${pkgs.llvmPackages_latest.libclang.lib}/lib";
+
+            # do not let test results block the build process
+            doCheck = false;
+          };
+        };
+
+      packages = forAllSystems (
+        system: {
+          default = nixpkgsFor.${system}.grin;
+        }
+      );
+    };
+}