From 26352c706586ee82cfbf82d4cbeb18e5f700a9c3 Mon Sep 17 00:00:00 2001
From: Luke Granger-Brown <hg@lukegb.com>
Date: Wed, 18 Nov 2020 02:02:23 +0000
Subject: [PATCH] ops/nixos: add ability to define additional things to be
 scraped, use this for coredns

---
 ops/nixos/default.nix       | 26 +++++++++++++++++---------
 ops/nixos/lib/common.nix    |  4 ++++
 ops/nixos/swann/default.nix |  1 +
 3 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/ops/nixos/default.nix b/ops/nixos/default.nix
index 885f1a1468..6e7042b143 100644
--- a/ops/nixos/default.nix
+++ b/ops/nixos/default.nix
@@ -23,16 +23,24 @@ let
   systemDrvs = mapAttrs (_: sys: sys.config.system.build.toplevel) evaledSystems;
   systemTailscaleIPs = lib.mapAttrs' (n: v: lib.nameValuePair v [n]) (lib.filterAttrs (n: v: v != null) (mapAttrs (_: sys: sys.config.my.ip.tailscale) evaledSystems));
 
-  systemExporters = builtins.listToAttrs (builtins.concatLists (lib.mapAttrsToList (sysName: sys: lib.mapAttrsToList (exporterName: exporter: let jobName = "${sysName}/exporters/${exporterName}"; in lib.nameValuePair jobName {
-    job_name = jobName;
-    static_configs = [{
-      targets = ["${sysName}:${toString exporter.port}"];
-      labels = {
-        system = sysName;
-        exporter = exporterName;
+  systemExporters = let
+    exportersForSystem = sysName: sys: let
+      mkExporter = exporterName: exporterPort: let jobName = "${sysName}/exporters/${exporterName}"; in lib.nameValuePair jobName {
+        job_name = jobName;
+        static_configs = [{
+          targets = ["${sysName}:${toString exporterPort}"];
+          labels = {
+            system = sysName;
+            exporter = exporterName;
+          };
+        }];
       };
-    }];
-  }) (lib.filterAttrs (_: exporter: exporter.enable) sys.config.services.prometheus.exporters)) evaledSystems));
+      stockExporters = lib.mapAttrsToList (exporterName: exporter: mkExporter exporterName exporter.port) (lib.filterAttrs (_: exporter: exporter.enable) sys.config.services.prometheus.exporters);
+      customExporters = lib.mapAttrsToList mkExporter sys.config.my.prometheus.additionalExporterPorts;
+    in
+      stockExporters ++ customExporters;
+  in
+    builtins.listToAttrs (builtins.concatLists (lib.mapAttrsToList exportersForSystem evaledSystems));
 in systemDrvs // {
   systems = systemDrvs;
   systemExporters = systemExporters;
diff --git a/ops/nixos/lib/common.nix b/ops/nixos/lib/common.nix
index e0a19b42e8..82ee56ca9d 100644
--- a/ops/nixos/lib/common.nix
+++ b/ops/nixos/lib/common.nix
@@ -17,6 +17,10 @@ in
     type = lib.types.nullOr lib.types.anything;
     default = null;
   };
+  options.my.prometheus.additionalExporterPorts = lib.mkOption {
+    type = lib.types.attrsOf lib.types.port;
+    default = {};
+  };
 
   options.my.ip.tailscale = lib.mkOption {
     type = lib.types.nullOr lib.types.string;
diff --git a/ops/nixos/swann/default.nix b/ops/nixos/swann/default.nix
index 538e16a76f..ca0d1fa4ac 100644
--- a/ops/nixos/swann/default.nix
+++ b/ops/nixos/swann/default.nix
@@ -209,6 +209,7 @@ in {
       }
     '';
   };
+  my.prometheus.additionalExporterPorts.coredns = 9153;
   networking.resolvconf.extraConfig = ''
     name_servers='127.0.0.53'
   '';