Add nix flake support (#965)

* Add nix flake support

* Apply suggestions from code review

Co-authored-by: Noah S-C <[email protected]>

* Move nix files to /contrib

---------

Co-authored-by: Noah S-C <[email protected]>

Author: ryuheechul

contrib/.gitignore

@@ -0,0 +1,2 @@
+# for `nix build`
+result

contrib/default.nix

@@ -0,0 +1,10 @@
+(import
+  (
+    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  { src = ./.; }
+).defaultNix

contrib/flake.lock

@@ -0,0 +1,31 @@
+{
+  description = "Sourcegraph CLI";
+
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+    flake-compat = {
+      url = "github:edolstra/flake-compat";
+      flake = false;
+    };
+  };
+
+  outputs = { self, nixpkgs, flake-utils, ... }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+      in
+      rec {
+        packages.src-cli = with pkgs; buildGoModule.override { go = pkgs.go_1_19; } {
+          pname = "src-cli";
+          version = self.shortRev or "dirty";
+          src = ../.;
+
+          subPackages = [ "cmd/src" ];
+
+          vendorSha256 = "sha256-NMLrBYGscZexnR43I4Ku9aqzJr38z2QAnZo0RouHFrc=";
+        };
+        packages.default = packages.src-cli;
+      }
+    );
+}