Move nix-daemon exporter to modules

Reviewed-by: Aleix Boné <abonerib@bsc.es>
Reviewed-by: Aleix Roca Nonell <aleix.rocanonell@bsc.es>

m/hut/monitoring.nix

@@ -6,7 +6,7 @@
     ../module/meteocat-exporter.nix
     ../module/upc-qaire-exporter.nix
     ./gpfs-probe.nix
-    ./nix-daemon-exporter.nix
+    ../module/nix-daemon-exporter.nix
   ];
 
   age.secrets.grafanaJungleRobotPassword = {

m/hut/nix-daemon-builds.sh

@@ -1,26 +0,0 @@
-#!/bin/sh
-
-# Locate nix daemon pid
-nd=$(pgrep -o nix-daemon)
-
-# Locate children of nix-daemon
-pids1=$(tr ' ' '\n' < "/proc/$nd/task/$nd/children")
-
-# For each children, locate 2nd level children
-pids2=$(echo "$pids1" | xargs -I @ /bin/sh -c 'cat /proc/@/task/*/children' | tr ' ' '\n')
-
-cat <<EOF
-HTTP/1.1 200 OK
-Content-Type: text/plain; version=0.0.4; charset=utf-8; escaping=values
-
-# HELP nix_daemon_build Nix daemon derivation build state.
-# TYPE nix_daemon_build gauge
-EOF
-
-for pid in $pids2; do
-  name=$(cat /proc/$pid/environ 2>/dev/null | tr '\0' '\n' | rg "^name=(.+)" - --replace '$1' | tr -dc ' [:alnum:]_\-\.')
-  user=$(ps -o uname= -p "$pid")
-  if [ -n "$name" -a -n "$user" ]; then
-    printf 'nix_daemon_build{user="%s",name="%s"} 1\n' "$user" "$name"
-  fi
-done

m/hut/nix-daemon-exporter.nix

@@ -1,23 +0,0 @@
-{ pkgs, config, lib, ... }:
-let
-  script = pkgs.runCommand "nix-daemon-exporter.sh" { }
-    ''
-      cp ${./nix-daemon-builds.sh} $out;
-      chmod +x $out
-    ''
-  ;
-in
-{
-  systemd.services.nix-daemon-exporter = {
-    description = "Daemon to export nix-daemon metrics";
-    path = [ pkgs.procps pkgs.ripgrep ];
-    wantedBy = [ "default.target" ];
-    serviceConfig = {
-      Type = "simple";
-      ExecStart = "${pkgs.socat}/bin/socat TCP4-LISTEN:9999,fork EXEC:${script}";
-      # Needed root to read the environment, potentially unsafe
-      User = "root";
-      Group = "root";
-    };
-  };
-}