Add script to monitor GPFS

m/hut/gpfs-probe.nix

@@ -0,0 +1,31 @@
+{ pkgs, config, lib, ... }:
+let
+  gpfs-probe-script = pkgs.runCommand "gpfs-probe.sh" { }
+    ''
+      cp ${./gpfs-probe.sh} $out;
+      chmod +x $out
+    ''
+  ;
+in
+{
+  # Use a new user to handle the SSH keys
+  users.groups.ssh-robot = { };
+  users.users.ssh-robot = {
+    description = "SSH Robot";
+    isNormalUser = true;
+    home = "/var/lib/ssh-robot";
+  };
+
+  systemd.services.gpfs-probe = {
+    description = "Daemon to report GPFS latency via SSH";
+    path = [ pkgs.openssh pkgs.netcat ];
+    after = [ "network.target" ];
+    wantedBy = [ "default.target" ];
+    serviceConfig = {
+      Type = "simple";
+      ExecStart = "${pkgs.socat}/bin/socat -d2 TCP4-LISTEN:9966,fork EXEC:${gpfs-probe-script}";
+      User = "ssh-robot";
+      Group = "ssh-robot";
+    };
+  };
+}