From 5fa27d3eb205a1d17861bcd82e831e66fd288988 Mon Sep 17 00:00:00 2001
From: kat witch <kat@kittywit.ch>
Date: Mon, 6 Sep 2021 16:17:44 +0100
Subject: [PATCH] hosts/shinmyoumaru: DHT22 exporting functional

---
 config/hosts/shinmyoumaru/nixos.nix        |  2 +
 config/profiles/hardware/raspi.nix         | 10 +++++
 config/services/dht22-exporter/default.nix | 51 ++++++++++++++++++++++
 3 files changed, 63 insertions(+)
 create mode 100644 config/services/dht22-exporter/default.nix

diff --git a/config/hosts/shinmyoumaru/nixos.nix b/config/hosts/shinmyoumaru/nixos.nix
index 7c11925d..15355d18 100644
--- a/config/hosts/shinmyoumaru/nixos.nix
+++ b/config/hosts/shinmyoumaru/nixos.nix
@@ -6,6 +6,8 @@
   imports = with meta; [
     profiles.hardware.raspi
     profiles.base
+    services.dnscrypt-proxy
+    services.dht22-exporter
     ./image.nix
   ];
 
diff --git a/config/profiles/hardware/raspi.nix b/config/profiles/hardware/raspi.nix
index 041bcdc2..10f2736a 100644
--- a/config/profiles/hardware/raspi.nix
+++ b/config/profiles/hardware/raspi.nix
@@ -30,6 +30,16 @@
     };
   };
 
+  services.udev.extraRules = ''
+    SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio", MODE="0660"
+    SUBSYSTEM=="gpio", KERNEL=="gpiochip*", ACTION=="add", PROGRAM="${pkgs.runtimeShell} -c 'chown root:gpio /sys/class/gpio/export /sys/class/gpio/unexport ; chmod 220 /sys/class/gpio/export /sys/class/gpio/unexport'"
+    SUBSYSTEM=="gpio", KERNEL=="gpio*", ACTION=="add", PROGRAM="${pkgs.runtimeShell} -c 'chown root:gpio /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value ; chmod 660 /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value'"
+
+T
+  '';
+
+  users.groups.gpio = {};
+
   environment.noXlibs = true;
   documentation.info.enable = false;
   documentation.man.enable = false;
diff --git a/config/services/dht22-exporter/default.nix b/config/services/dht22-exporter/default.nix
new file mode 100644
index 00000000..0ca6969a
--- /dev/null
+++ b/config/services/dht22-exporter/default.nix
@@ -0,0 +1,51 @@
+{ config, lib, pkgs, ... }: with lib; let
+  cfg = config.services.dht22-exporter;
+in {
+  options.services.dht22-exporter.socat = {
+    enable = mkEnableOption "socat service";
+    package = mkOption {
+      type = types.package;
+      default = pkgs.socat;
+    };
+    addresses = mkOption {
+      type = with types; coercedTo str singleton (listOf str);
+      default = singleton "::1";
+    };
+  };
+  config = {
+    systemd.services = mkIf cfg.socat.enable {
+      dht22-exporter-socat = let
+        scfg = cfg.socat;
+        service = singleton "dht22-exporter.service";
+      in {
+        after = service;
+        bindsTo = service;
+        serviceConfig = {
+          DynamicUser = true;
+        };
+        script = let
+          port = toString (if cfg.port == null then 8001 else cfg.port);
+          addresser = addr: "${scfg.package}/bin/socat TCP6-LISTEN:${port},bind=${addr},fork TCP4:localhost:${port}";
+          lines = map addresser scfg.addresses;
+        in ''
+          ${concatStringsSep "\n" lines}
+        '';
+      };
+    };
+
+    users.users.dht22-exporter = {
+      isSystemUser = true;
+    };
+
+    services.dht22-exporter = {
+      enable = true;
+      platform = "pi";
+      address = "127.0.0.1";
+      socat = {
+        enable = true;
+      };
+      user = "dht22-exporter";
+      group = "gpio";
+    };
+  };
+}