nixos/esphome: init module

nixos/modules/services/home-automation/esphome.nix

@@ -0,0 +1,136 @@
+{ config, lib, pkgs, ... }:
+
+let
+  inherit (lib)
+    literalExpression
+    maintainers
+    mkEnableOption
+    mkIf
+    mkOption
+    mdDoc
+    types
+    ;
+
+  cfg = config.services.esphome;
+
+  stateDir = "/var/lib/esphome";
+
+  esphomeParams =
+    if cfg.enableUnixSocket
+    then "--socket /run/esphome/esphome.sock"
+    else "--address ${cfg.address} --port ${toString cfg.port}";
+in
+{
+  meta.maintainers = with maintainers; [ oddlama ];
+
+  options.services.esphome = {
+    enable = mkEnableOption (mdDoc "esphome");
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.esphome;
+      defaultText = literalExpression "pkgs.esphome";
+      description = mdDoc "The package to use for the esphome command.";
+    };
+
+    enableUnixSocket = mkOption {
+      type = types.bool;
+      default = false;
+      description = lib.mdDoc "Listen on a unix socket `/run/esphome/esphome.sock` instead of the TCP port.";
+    };
+
+    address = mkOption {
+      type = types.str;
+      default = "localhost";
+      description = mdDoc "esphome address";
+    };
+
+    port = mkOption {
+      type = types.port;
+      default = 6052;
+      description = mdDoc "esphome port";
+    };
+
+    openFirewall = mkOption {
+      default = false;
+      type = types.bool;
+      description = mdDoc "Whether to open the firewall for the specified port.";
+    };
+
+    allowedDevices = mkOption {
+      default = ["char-ttyS" "char-ttyUSB"];
+      example = ["/dev/serial/by-id/usb-Silicon_Labs_CP2102_USB_to_UART_Bridge_Controller_0001-if00-port0"];
+      description = lib.mdDoc ''
+        A list of device nodes to which {command}`esphome` has access to.
+        Refer to DeviceAllow in systemd.resource-control(5) for more information.
+        Beware that if a device is referred to by an absolute path instead of a device category,
+        it will only allow devices that already are plugged in when the service is started.
+      '';
+      type = types.listOf types.str;
+    };
+  };
+
+  config = mkIf cfg.enable {
+    networking.firewall.allowedTCPPorts = mkIf (cfg.openFirewall && !cfg.enableUnixSocket) [cfg.port];
+
+    systemd.services.esphome = {
+      description = "ESPHome dashboard";
+      after = ["network.target"];
+      wantedBy = ["multi-user.target"];
+      path = [cfg.package];
+
+      # platformio fails to determine the home directory when using DynamicUser
+      environment.PLATFORMIO_CORE_DIR = "${stateDir}/.platformio";
+
+      serviceConfig = {
+        ExecStart = "${cfg.package}/bin/esphome dashboard ${esphomeParams} ${stateDir}";
+        DynamicUser = true;
+        User = "esphome";
+        Group = "esphome";
+        WorkingDirectory = stateDir;
+        StateDirectory = "esphome";
+        StateDirectoryMode = "0750";
+        Restart = "on-failure";
+        RuntimeDirectory = mkIf cfg.enableUnixSocket "esphome";
+        RuntimeDirectoryMode = "0750";
+
+        # Hardening
+        CapabilityBoundingSet = "";
+        LockPersonality = true;
+        MemoryDenyWriteExecute = true;
+        DevicePolicy = "closed";
+        DeviceAllow = map (d: "${d} rw") cfg.allowedDevices;
+        SupplementaryGroups = ["dialout"];
+        #NoNewPrivileges = true; # Implied by DynamicUser
+        PrivateUsers = true;
+        #PrivateTmp = true; # Implied by DynamicUser
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = true;
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectProc = "invisible";
+        ProcSubset = "pid";
+        ProtectSystem = "strict";
+        #RemoveIPC = true; # Implied by DynamicUser
+        RestrictAddressFamilies = [
+          "AF_INET"
+          "AF_INET6"
+          "AF_NETLINK"
+          "AF_UNIX"
+        ];
+        RestrictNamespaces = false; # Required by platformio for chroot
+        RestrictRealtime = true;
+        #RestrictSUIDSGID = true; # Implied by DynamicUser
+        SystemCallArchitectures = "native";
+        SystemCallFilter = [
+          "@system-service"
+          "@mount" # Required by platformio for chroot
+        ];
+        UMask = "0077";
+      };
+    };
+  };
+}