enable node exporter on all machines

enable prometheus scraper and web interface on warwick

nix/machines/warwick.nix

@@ -3,5 +3,7 @@
     kind = "physical";
     arch = "aarch64-linux";
     isRaspberryPi = true;
+
+    nixosModule.lab.services.prometheus.server.enable = true;
   };
 }

nix/modules/default.nix

@@ -6,5 +6,6 @@
     ./networking
     ./data-sharing.nix
     ./globals.nix
+    ./prometheus.nix
   ];
 }

nix/modules/prometheus.nix

@@ -0,0 +1,49 @@
+{ lib, config, machines, ... }:
+let
+  cfg = config.lab.services.prometheus;
+in
+{
+  options = {
+    lab.services.prometheus = {
+      enable = lib.mkOption {
+        default = true;
+        type = lib.types.bool;
+      };
+
+      server.enable = lib.mkOption {
+        default = false;
+        type = lib.types.bool;
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    networking.firewall.allowedTCPPorts = [ config.services.prometheus.exporters.node.port ]
+      ++ lib.lists.optionals cfg.server.enable [ config.services.prometheus.port ];
+
+    services.prometheus = {
+      enable = cfg.server.enable;
+
+      exporters = {
+        node = {
+          enable = true;
+        };
+      };
+
+      scrapeConfigs = lib.mkIf cfg.server.enable (
+        lib.attrsets.mapAttrsToList
+          (name: machine:
+            let
+              domain = if machine.isPhysical then "hyp" else "dmz";
+            in
+            {
+              job_name = name;
+              static_configs = [{
+                targets = [ "${name}.${domain}:${toString config.services.prometheus.exporters.node.port}" ];
+              }];
+            })
+          machines
+      );
+    };
+  };
+}