feat: add nix flake packaging

.gitignore

@@ -1 +1,5 @@
 bin/*
+
+# Nix build artifacts
+result
+result-*

README.md

@@ -36,10 +36,11 @@ Sarin is designed for efficient HTTP load testing with minimal resource consumpt
 
 ## Installation
 
-### Docker (Recommended)
+<details open>
+<summary><b>Docker</b></summary>
 
 ```sh
-docker pull aykhans/sarin:latest
+docker run -it aykhans/sarin:latest --version
 ```
 
 With a local config file:
@@ -54,11 +55,46 @@ With a remote config file:
 docker run --rm -it aykhans/sarin -f https://example.com/config.yaml
 ```
 
-### Pre-built Binaries
+</details>
+
+<details>
+<summary><b>Nix</b></summary>
+
+Run directly without installing (requires flakes enabled):
+
+```sh
+nix run github:aykhans/sarin/v1.3.2 -- -U http://example.com -r 100 -c 10
+```
+
+Install into your profile:
+
+```sh
+nix profile install github:aykhans/sarin/v1.3.2
+```
+
+Or add it to your own flake via the overlay:
+
+```nix
+{
+  inputs.sarin.url = "github:aykhans/sarin/v1.3.2";
+
+  # In your outputs, apply the overlay to nixpkgs:
+  # nixpkgs.overlays = [ inputs.sarin.overlays.default ];
+  # then reference pkgs.sarin
+}
+```
+
+</details>
+
+<details>
+<summary><b>Pre-built Binaries</b></summary>
 
 Download the latest binaries from the [releases](https://github.com/aykhans/sarin/releases) page.
 
-### Building from Source
+</details>
+
+<details>
+<summary><b>Building from Source</b></summary>
 
 Requires [Go 1.26+](https://golang.org/dl/).
 
@@ -74,6 +110,8 @@ CGO_ENABLED=0 go build \
     -o sarin ./cmd/cli/main.go
 ```
 
+</details>
+
 ## Quick Start
 
 Send 10,000 GET requests with 50 concurrent connections and a random User-Agent for each request:

flake.lock

@@ -0,0 +1,27 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1784796856,
+        "narHash": "sha256-wWFrV5/Qbm+lyt5x20E/bSbfJiGKMo4RCxZV8cl/WZI=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "e2587caef70cea85dd97d7daab492899902dbf5d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

@@ -0,0 +1,55 @@
+{
+  description = "Sarin - high-performance HTTP load testing tool built with Go and fasthttp";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+  };
+
+  outputs = { self, nixpkgs }:
+    let
+      inherit (nixpkgs) lib;
+
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "x86_64-darwin"
+        "aarch64-darwin"
+      ];
+
+      forAllSystems = f: lib.genAttrs systems (system: f nixpkgs.legacyPackages.${system});
+
+      rev = self.rev or self.dirtyRev or "unknown";
+
+      # self.lastModifiedDate is "YYYYMMDDHHMMSS"; reshape to RFC 3339 (UTC).
+      raw = self.lastModifiedDate or "19700101000000";
+      s = i: n: lib.substring i n raw;
+      buildDate = "${s 0 4}-${s 4 2}-${s 6 2}T${s 8 2}:${s 10 2}:${s 12 2}Z";
+    in
+    {
+      packages = forAllSystems (pkgs: {
+        default = pkgs.callPackage ./nix/package.nix {
+          inherit rev buildDate;
+        };
+      });
+
+      # nix run github:aykhans/sarin -- <args>
+      apps = forAllSystems (pkgs: {
+        default = {
+          type = "app";
+          program = "${self.packages.${pkgs.system}.default}/bin/sarin";
+          meta.description = "High-performance HTTP load testing tool";
+        };
+      });
+
+      devShells = forAllSystems (pkgs: {
+        default = pkgs.mkShell {
+          packages = [ pkgs.go_1_26 pkgs.golangci-lint pkgs.go-task ];
+        };
+      });
+
+      # For downstream flakes: inputs.sarin.overlays.default
+      overlays.default = final: _prev: {
+        sarin = final.callPackage ./nix/package.nix { };
+      };
+    };
+}

nix/package.nix

@@ -0,0 +1,44 @@
+{ lib
+, stdenv
+, buildGoModule
+, go_1_26
+, rev ? "unknown"
+, buildDate ? "unknown"
+}:
+
+(buildGoModule.override { go = go_1_26; }) (finalAttrs: {
+  pname = "sarin";
+  version = "1.3.2"; # bump per release
+
+  src = lib.cleanSource ../.;
+
+  vendorHash = "sha256-BMH0alJeZoK/8cE9Y+s++G7D+Dg5xcZNTU4zkRMBpfU=";
+
+  subPackages = [ "cmd/cli" ];
+
+  env.CGO_ENABLED = 0; # fully static binary
+
+  ldflags = [
+    "-s"
+    "-w"
+    "-X=go.aykhans.me/sarin/internal/version.Version=v${finalAttrs.version}"
+    "-X=go.aykhans.me/sarin/internal/version.GitCommit=${rev}"
+    "-X=go.aykhans.me/sarin/internal/version.BuildDate=${buildDate}"
+    # Value has spaces, so it is single-quoted: `go build` splits -ldflags
+    # shell-style and honours the quotes, keeping this as one -X value.
+    "-X 'go.aykhans.me/sarin/internal/version.GoVersion=go version go${go_1_26.version} ${stdenv.hostPlatform.go.GOOS}/${stdenv.hostPlatform.go.GOARCH}'"
+  ];
+
+  # cmd/cli produces a binary named "cli"; rename it to "sarin".
+  postInstall = ''
+    mv $out/bin/cli $out/bin/sarin
+  '';
+
+  meta = {
+    description = "High-performance HTTP load testing tool built with Go and fasthttp";
+    homepage = "https://github.com/aykhans/sarin";
+    license = lib.licenses.mit;
+    mainProgram = "sarin";
+    maintainers = [ ];
+  };
+})