Initial scaffold: NixOS + SvelteKit dashboard + Python renderer

2026-06-07 18:15:06 +02:00
commit 50256fa384
25 changed files with 4491 additions and 0 deletions
@@ -0,0 +1,79 @@
+{ config, lib, pkgs, self, ... }:
+
+let
+  cfg = config.eink.renderer;
+
+  pythonEnv = pkgs.python3.withPackages (ps: with ps; [
+    pillow
+    numpy
+    playwright
+    requests
+    # The Waveshare 12.48" lib is not packaged in nixpkgs; we vendor it
+    # under renderer/waveshare/ and import it as a local module.
+    spidev
+    rpi-gpio
+  ]);
+in
+{
+  options.eink.renderer = {
+    enable = lib.mkEnableOption "E-paper renderer (Playwright + Pillow + Waveshare driver)";
+
+    dashboardUrl = lib.mkOption {
+      type = lib.types.str;
+      default = "http://127.0.0.1:3000";
+    };
+
+    refreshSeconds = lib.mkOption {
+      type = lib.types.int;
+      default = 300;
+      description = "Seconds between full panel refreshes. Below 180 will wear the panel.";
+    };
+
+    panel = lib.mkOption {
+      type = lib.types.enum [ "bw" "bwr" ];
+      default = "bw";
+      description = "Panel variant: bw = 12.48\" B/W, bwr = 12.48\" Module (B) B/W/Red.";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    # Playwright needs a Chromium and its system deps. Use the nixpkgs one
+    # so the binary path is stable across rebuilds (not the npm-downloaded
+    # browser, which won't find its sandbox libs on NixOS).
+    systemd.services.eink-renderer = {
+      description = "E-paper renderer loop";
+      after = [ "eink-dashboard.service" "network-online.target" ];
+      wants = [ "eink-dashboard.service" ];
+      wantedBy = [ "multi-user.target" ];
+
+      environment = {
+        DASHBOARD_URL = cfg.dashboardUrl;
+        REFRESH_SECONDS = toString cfg.refreshSeconds;
+        PANEL_VARIANT = cfg.panel;
+        PLAYWRIGHT_BROWSERS_PATH = "${pkgs.playwright-driver.browsers}";
+        PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD = "1";
+        PYTHONPATH = "${self}/renderer";
+      };
+
+      serviceConfig = {
+        Type = "simple";
+        ExecStart = "${pythonEnv}/bin/python ${self}/renderer/render.py";
+        Restart = "always";
+        RestartSec = "10s";
+
+        # The Waveshare lib needs raw SPI + GPIO. Run as a dedicated user
+        # in the spi/gpio groups rather than root.
+        User = "eink";
+        Group = "eink";
+        SupplementaryGroups = [ "spi" "gpio" ];
+      };
+    };
+
+    users.users.eink = {
+      isSystemUser = true;
+      group = "eink";
+      extraGroups = [ "spi" "gpio" ];
+    };
+    users.groups.eink = {};
+  };
+}