From ee58f7a4eef3a85ff7dda20c709e230a27cadff1 Mon Sep 17 00:00:00 2001
From: Noah Masur <7386960+nmasur@users.noreply.github.com>
Date: Wed, 5 Jul 2023 14:19:54 -0600
Subject: [PATCH] abstract grafana in prometheus config

---
 modules/nixos/services/prometheus.nix | 29 ++++++++++++++-------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/modules/nixos/services/prometheus.nix b/modules/nixos/services/prometheus.nix
index 7977ee2..fb7e5df 100644
--- a/modules/nixos/services/prometheus.nix
+++ b/modules/nixos/services/prometheus.nix
@@ -6,10 +6,13 @@
     default = null;
   };
 
-  # If hosting Grafana, host local Prometheus and listen for inbound jobs.
-  # If not hosting Grafana, send remote Prometheus writes to primary host
+  config = let
 
-  config = lib.mkIf config.services.prometheus.enable {
+    # If hosting Grafana, host local Prometheus and listen for inbound jobs. If
+    # not hosting Grafana, send remote Prometheus writes to primary host.
+    isServer = config.services.grafana.enable;
+
+  in lib.mkIf config.services.prometheus.enable {
 
     services.prometheus = {
       exporters.node.enable = true;
@@ -17,10 +20,9 @@
         job_name = "local";
         static_configs = [{ targets = [ "127.0.0.1:9100" ]; }];
       }];
-      webExternalUrl = lib.mkIf config.services.grafana.enable
-        "https://${config.prometheusServer}";
+      webExternalUrl = lib.mkIf isServer "https://${config.prometheusServer}";
       # Web config file: https://prometheus.io/docs/prometheus/latest/configuration/https/
-      webConfigFile = lib.mkIf config.services.grafana.enable
+      webConfigFile = lib.mkIf isServer
         ((pkgs.formats.yaml { }).generate "webconfig.yml" {
           basic_auth_users = {
             # Generate password: htpasswd -nBC 10 "" | tr -d ':\n'
@@ -29,7 +31,7 @@
               "$2y$10$r7FWHLHTGPAY312PdhkPEuvb05aGn9Nk1IO7qtUUUjmaDl35l6sLa";
           };
         });
-      remoteWrite = lib.mkIf (!config.services.grafana.enable) [{
+      remoteWrite = lib.mkIf (!isServer) [{
         name = config.networking.hostName;
         url = "https://${config.prometheusServer}";
         basic_auth = {
@@ -41,20 +43,19 @@
     };
 
     # Create credentials file for remote Prometheus push
-    secrets.prometheus = lib.mkIf (!config.services.grafana.enable) {
+    secrets.prometheus = lib.mkIf (!isServer) {
       source = ../../../private/prometheus.age;
       dest = "${config.secretsDirectory}/prometheus";
       owner = "prometheus";
       group = "prometheus";
       permissions = "0440";
     };
-    systemd.services.prometheus-secret =
-      lib.mkIf (!config.services.grafana.enable) {
-        requiredBy = [ "prometheus.service" ];
-        before = [ "prometheus.service" ];
-      };
+    systemd.services.prometheus-secret = lib.mkIf (!isServer) {
+      requiredBy = [ "prometheus.service" ];
+      before = [ "prometheus.service" ];
+    };
 
-    caddy.routes = lib.mkIf config.services.grafana.enable [{
+    caddy.routes = lib.mkIf isServer [{
       match = [{ host = [ config.prometheusServer ]; }];
       handle = [{
         handler = "reverse_proxy";