Add nixos module

flake.nix

@@ -52,11 +52,16 @@
 
     overlays = {
       default = self.overlays.mysqladm-rs;
-      greg-ng = final: prev: {
+      mysqladm-rs = final: prev: {
         inherit (self.packages.${prev.system}) mysqladm-rs;
       };
     };
 
+    nixosModules = {
+      default = self.nixosModules.mysqladm-rs;
+      mysqladm-rs = import ./nix/module.nix;
+    };
+
     packages = let
       cargoToml = builtins.fromTOML (builtins.readFile ./Cargo.toml);
       cargoLock = ./Cargo.lock;

nix/module.nix

@@ -0,0 +1,141 @@
+{ config, pkgs, lib, ... }:
+let
+  cfg = config.services.mysqladm-rs;
+  format = pkgs.formats.toml { };
+in
+{
+  options.services.mysqladm-rs = {
+    enable = lib.mkEnableOption "Enable mysqladm-rs";
+
+    package = lib.mkPackageOption pkgs "mysqladm-rs" { };
+
+    createLocalDatabaseUser = lib.mkOption {
+      type = lib.types.bool;
+      default = false;
+      description = "Create a local database user for mysqladm-rs";
+    };
+
+    settings = lib.mkOption {
+      default = { };
+      type = lib.types.submodule {
+        freeformType = format.type;
+        options  = {
+          server = {
+            socket_path = lib.mkOption {
+              type = lib.types.path;
+              default = "/var/run/mysqladm/mysqladm.sock";
+              description = "Path to the MySQL socket";
+            };
+          };
+
+          mysql = {
+            socket_path = lib.mkOption {
+              type = with lib.types; nullOr path;
+              default = "/var/run/mysqld/mysqld.sock";
+              description = "Path to the MySQL socket";
+            };
+            host = lib.mkOption {
+              type = with lib.types; nullOr str;
+              default = null;
+              description = "MySQL host";
+            };
+            port = lib.mkOption {
+              type = with lib.types; nullOr port;
+              default = 3306;
+              description = "MySQL port";
+            };
+            username = lib.mkOption {
+              type = lib.types.str;
+              default = "mysqladm";
+              description = "MySQL username";
+            };
+            passwordFile = lib.mkOption {
+              type = with lib.types; nullOr path;
+              default = null;
+              description = "Path to a file containing the MySQL password";
+            };
+            timeout = lib.mkOption {
+              type = lib.types.ints.positive;
+              default = 2;
+              description = "Number of seconds to wait for a response from the MySQL server";
+            };
+          };
+        };
+      };
+    };
+  };
+
+  config = let
+    nullStrippedConfig = lib.filterAttrsRecursive (_: v: v != null) cfg.settings;
+    configFile = format.generate "mysqladm-rs.conf" nullStrippedConfig;
+  in lib.mkIf config.services.mysqladm-rs.enable {
+    environment.systemPackages = [ cfg.package ];
+
+    services.mysql.ensureUsers = lib.mkIf cfg.createLocalDatabaseUser [
+      {
+        name = cfg.settings.mysql.username;
+        ensurePermissions = {
+          "mysql.*" = "SELECT, INSERT, UPDATE, DELETE";
+          "*.*" = "CREATE USER, GRANT OPTION";
+        };
+      }
+    ];
+
+    systemd.services."mysqladm@" = {
+      description = "MySQL administration tool for non-admin users";
+      environment.RUST_LOG = "debug";
+      serviceConfig = {
+        Type = "notify";
+        ExecStart = "${lib.getExe cfg.package} server socket-activate --config ${configFile}";
+
+        User = "mysqladm";
+        Group = "mysqladm";
+        DynamicUser = true;
+
+        # This is required to read unix user/group details.
+        PrivateUsers = false;
+
+        CapabilityBoundingSet = "";
+        LockPersonality = true;
+        MemoryDenyWriteExecute = true;
+        NoNewPrivileges = true;
+        PrivateDevices = true;
+        PrivateMounts = true;
+        PrivateTmp = "yes";
+        ProcSubset = "pid";
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectProc = "invisible";
+        ProtectSystem = "strict";
+        RemoveIPC = true;
+        UMask = "0000";
+        RestrictAddressFamilies = [ "AF_UNIX" "AF_INET" "AF_INET6" ];
+        RestrictNamespaces = true;
+        RestrictRealtime = true;
+        RestrictSUIDSGID = true;
+        SystemCallArchitectures = "native";
+        SystemCallFilter = [
+          "@system-service"
+          "~@privileged"
+          "~@resources"
+        ];
+      };
+    };
+
+    systemd.sockets."mysqladm" = {
+      description = "MySQL administration tool for non-admin users";
+      wantedBy = [ "sockets.target" ];
+      restartTriggers = [ configFile ];
+      socketConfig = {
+        ListenStream = cfg.settings.server.socket_path;
+        Accept = "yes";
+        PassCredentials = true;
+      };
+    };
+  };
+}