nix: add nix module and runnable VM

.gitignore

@@ -1,3 +1,9 @@
+# Rust
 /target
+
+# Nix
 result
 result-*
+
+# Nix VM
+*.qcow2

flake.nix

@@ -32,6 +32,20 @@
       };
     in f system pkgs toolchain);
   in {
+    apps = let
+      mkApp = program: description: {
+        type = "app";
+        program = toString program;
+        meta = {
+          inherit description;
+        };
+      };
+      mkVm = name: mkApp "${self.nixosConfigurations.${name}.config.system.build.vm}/bin/run-nixos-vm";
+    in forAllSystems (system: pkgs: _: {
+      default = self.apps.${system}.vm;
+      vm = mkVm "vm" "Start a NixOS VM with bro installed";
+    });
+
     devShells = forAllSystems (system: pkgs: toolchain: {
       default = pkgs.mkShell {
         nativeBuildInputs = with pkgs; [
@@ -53,6 +67,15 @@
       };
     };
 
+    nixosModules = {
+      default = self.nixosModules.bro;
+      bro = import ./nix/module.nix;
+    };
+
+    nixosConfigurations = {
+      vm = import ./nix/vm.nix { inherit self nixpkgs; };
+    };
+
     packages = forAllSystems (system: pkgs: _:
       let
       cargoToml = fromTOML (builtins.readFile ./Cargo.toml);

nix/module.nix

@@ -0,0 +1,169 @@
+{ config, lib, pkgs, ... }:
+let
+  cfg = config.services.bro;
+in
+{
+  options.services.bro = {
+    enable = lib.mkEnableOption "";
+
+    package = lib.mkPackageOption pkgs "bro" { };
+
+    instances = lib.mkOption {
+      default = { };
+      type = lib.types.attrsOf (lib.types.submodule ({ name, config, ... }: {
+        options = {
+          enable = lib.mkEnableOption "";
+
+          client = {
+            logLevel = lib.mkOption {
+              type = lib.types.nullOr (lib.types.enum [ "trace" "debug" "info" "warn" "error" ]);
+              default = null;
+            };
+
+            settings = lib.mkOption {
+              default = { };
+              type = lib.types.submodule {
+                freeformType = with lib.types; oneOf [ str bool ];
+                options = {
+                  BRO_SOCKET_PATH = lib.mkOption {
+                    type = lib.types.path;
+                    default = "/run/bro/${name}.sock";
+                    defaultText = lib.literalExpression "\"/run/bro/${name}.sock\"";
+                  };
+
+                  BRO_FORWARD_ENV = lib.mkOption {
+                    type = lib.types.listOf lib.types.str;
+                    default = config.server.settings.allowed-env;
+                    example = [ "LS_COLORS" "TIME_STYLE" "QUOTING_STYLE" ];
+                  };
+
+                  BRO_FILE_FLAGS = lib.mkOption {
+                    type = lib.types.listOf lib.types.str;
+                    default = [ ];
+                    example = [ "-f" "--file" ];
+                  };
+
+                  BRO_FILE_ARGS = lib.mkOption {
+                    type = lib.types.bool;
+                    default = false;
+                    example = true;
+                  };
+
+                  BRO_CAPTURE_TTY_STDIN = lib.mkOption {
+                    type = lib.types.bool;
+                    default = false;
+                    example = true;
+                  };
+                };
+              };
+            };
+
+            programName = lib.mkOption {
+              type = lib.types.str;
+              default = lib.baseNameOf config.server.settings.executable;
+              defaultText = lib.literalExpression "lib.baseNameOf config.services.bro.instances.<name>.server.settings.executable";
+            };
+
+            package = lib.mkOption {
+              type = lib.types.package;
+              readOnly = true;
+              default = (
+                lib.warnIf
+                  (!cfg.enable || !config.enable)
+                  "Bro wrapper for instance '${name}' should not be used unless it is enabled."
+                (pkgs.writeShellApplication {
+                name = config.client.programName;
+                runtimeEnv = lib.pipe config.client.settings [
+                  (lib.mapAttrs (_: v: if lib.isBool v then (if v == true then "1" else null) else v))
+                  (lib.mapAttrs (_: v: if lib.isList v then (if v == [ ] then null else lib.concatStringsSep "," v) else v))
+                  (env: env // {
+                    RUST_LOG = config.client.logLevel;
+                  })
+                  (lib.filterAttrs (_: v: v != null))
+                ];
+                text = ''exec ${lib.getExe' cfg.package "bro-client"} "$@"'';
+              })).overrideAttrs { name = "bro-${name}-wrapper"; };
+            };
+          };
+
+          server = {
+            listenStreams = lib.mkOption {
+              type = lib.types.listOf lib.types.str;
+              default = [ "/run/bro/${name}.sock" ];
+            };
+
+            logLevel = lib.mkOption {
+              type = lib.types.nullOr (lib.types.enum [ "trace" "debug" "info" "warn" "error" ]);
+              default = "info";
+            };
+
+            settings = lib.mkOption {
+              default = { };
+              type = lib.types.submodule {
+                freeformType = lib.types.str;
+                options = {
+                  executable = lib.mkOption {
+                    type = lib.types.str;
+                  };
+
+                  fd-passing = lib.mkEnableOption "" // {
+                    default = true;
+                  };
+
+                  allowed-env = lib.mkOption {
+                    type = lib.types.listOf lib.types.str;
+                    default = [ ];
+                    example = [ "LS_COLORS" "TIME_STYLE" "QUOTING_STYLE" ];
+                  };
+
+                  inherit-env = lib.mkOption {
+                    type = lib.types.listOf lib.types.str;
+                    default = [ ];
+                    example = [ "LS_COLORS" "TIME_STYLE" "QUOTING_STYLE" ];
+                  };
+                };
+              };
+            };
+          };
+        };
+      }));
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    systemd = {
+      sockets = lib.mapAttrs' (name: instance: {
+        name = "bro-${name}";
+        value = {
+          wantedBy = [ "sockets.target" ];
+          listenStreams = instance.server.listenStreams;
+          socketConfig = {
+            AcceptFileDescriptors = lib.mkIf instance.server.settings.fd-passing true;
+          };
+        };
+      }) (lib.filterAttrs (name: instance: instance.enable) cfg.instances);
+
+      services = lib.mapAttrs' (name: instance: {
+        name = "bro-${name}";
+        value = {
+          environment.RUST_LOG = lib.mkIf (instance.server.logLevel != null) instance.server.logLevel;
+          serviceConfig = {
+            Type = "notify-reload";
+            ExecStart = let
+              args = lib.pipe instance.server.settings [
+                (lib.filterAttrs (_: v: v != [ ]))
+                (lib.mapAttrs (_: v: if lib.isList v then lib.concatStringsSep "," v else v))
+                (settings: settings // {
+                  systemd-socket = true;
+                })
+                (lib.cli.toCommandLineShellGNU { })
+              ];
+            in "${lib.getExe' cfg.package "bro-server"} ${args}";
+            Restart = "on-failure";
+            RestartSec = "5s";
+          };
+        };
+      }) (lib.filterAttrs (name: instance: instance.enable) cfg.instances);
+    };
+  };
+}

nix/vm.nix

@@ -0,0 +1,69 @@
+{ self, nixpkgs }:
+nixpkgs.lib.nixosSystem {
+  system = "x86_64-linux";
+  pkgs = import nixpkgs {
+    system = "x86_64-linux";
+    overlays = [
+      self.overlays.bro
+    ];
+  };
+  modules = [
+    "${nixpkgs}/nixos/modules/virtualisation/qemu-vm.nix"
+    "${nixpkgs}/nixos/tests/common/user-account.nix"
+
+    self.nixosModules.default
+
+    ({ config, lib, pkgs, ... }: {
+      system.stateVersion = config.system.nixos.release;
+      virtualisation.graphics = false;
+
+      services.getty.autologinUser = "alice";
+
+      users = {
+        users.alice.extraGroups = [
+          "wheel"
+          "systemd-journal"
+        ];
+        extraUsers.root.password = "root";
+        motd = ''
+          =================================
+          Welcome to the bro vm!
+
+          Password for alice is 'foobar'
+          Password for root is 'root'
+
+          To exit, press Ctrl+A, then X
+          =================================
+        '';
+      };
+
+      services.bro = {
+        enable = true;
+
+        instances.ls = {
+          enable = true;
+
+          client = {
+            settings.BRO_FILE_ARGS = true;
+          };
+
+          server = {
+            settings = {
+              executable = lib.getExe' pkgs.coreutils "ls";
+              allowed-env = [ "LS_COLORS" "TIME_STYLE" "QUOTING_STYLE" ];
+            };
+          };
+        };
+      };
+
+      environment.systemPackages = [
+        config.services.bro.instances.ls.client.package
+      ];
+
+      programs.vim = {
+        enable = true;
+        defaultEditor = true;
+      };
+    })
+  ];
+}