feat(hass): add firmware config for ESPHome

nixosModules/default.nix

@@ -3,6 +3,7 @@ self: {
   borgbackup = import ./borgbackup;
   desktop = import ./desktop self;
   docker = import ./docker self.inputs.khepri;
+  esphome-plus = import ./esphome-plus;
   kmscon = import ./kmscon;
   nvidia = import ./nvidia;
   plymouth = import ./plymouth;

nixosModules/esphome-plus/default.nix

@@ -0,0 +1,92 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit
+    (lib)
+    concatMapStringsSep
+    converge
+    elem
+    filterAttrsRecursive
+    getExe
+    mapAttrsToList
+    mkForce
+    mkIf
+    mkOption
+    optionalAttrs
+    optionals
+    optionalString
+    types
+    ;
+
+  cfg = config.services.esphome;
+
+  stateDir = "/var/lib/private/esphome";
+  esphomeParams =
+    if cfg.enableUnixSocket
+    then "--socket /run/esphome/esphome.sock"
+    else "--address ${cfg.address} --port ${toString cfg.port}";
+
+  format = pkgs.formats.yaml {};
+
+  # Adapted from https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/services/home-automation/home-assistant.nix
+  mkESPConf = name: cfg: let
+    filteredConfig = converge (filterAttrsRecursive (_: v: ! elem v [null])) cfg;
+  in {
+    name = "${name}.yaml";
+    file = pkgs.runCommandLocal "${name}.yaml" {} ''
+      cp ${format.generate "${name}.yaml" filteredConfig} $out
+      sed -i -e "s/'\!\([a-z_]\+\) \(.*\)'/\!\1 \2/;s/^\!\!/\!/;" $out
+      sed -i 's/ {}//g' $out
+    '';
+  };
+in {
+  options.services.esphome = {
+    firmwareConfigs = mkOption {
+      default = {};
+      type = with types; attrsOf anything;
+    };
+
+    deleteUnmanaged = mkOption {
+      default = true;
+      type = types.bool;
+    };
+  };
+
+  config = mkIf (cfg.enable) {
+    # FIXME: https://github.com/NixOS/nixpkgs/issues/339557
+    systemd.services.esphome = {
+      environment.PLATFORMIO_CORE_DIR = mkForce "${stateDir}/.platformio";
+
+      serviceConfig =
+        (optionalAttrs (cfg.firmwareConfigs != {}) {
+          ExecStartPre = getExe (pkgs.writeShellApplication {
+            name = "esphome-exec-start-pre";
+
+            runtimeInputs = optionals cfg.deleteUnmanaged [
+              pkgs.findutils
+            ];
+
+            text = ''
+              if [[ ! -d ${stateDir} ]]; then
+                  mkdir -p ${stateDir}
+              fi
+
+              ${optionalString cfg.deleteUnmanaged ''find ${stateDir} -name "*.yaml" ! -name "secrets.yaml" -delete''}
+
+              ${concatMapStringsSep
+                "\n"
+                (dev: ''cp -f "$(realpath "${dev.file}")" ${stateDir}/"${dev.name}"'')
+                (mapAttrsToList mkESPConf cfg.firmwareConfigs)}
+            '';
+          });
+        })
+        // {
+          ExecStart = mkForce "${cfg.package}/bin/esphome dashboard ${esphomeParams} ${stateDir}";
+          WorkingDirectory = mkForce stateDir;
+        };
+    };
+  };
+}