From bb371d19d35b9875b4ad9c0a20217b67ca62b58f Mon Sep 17 00:00:00 2001
From: arcnmx <git@git.arcn.mx>
Date: Thu, 30 May 2024 14:37:03 -0700
Subject: [PATCH] feat(extern): monitoring

---
 modules/extern/nixos/monitoring.nix | 139 ++++++++++++++++++++++++++++
 systems/extern-test/nixos.nix       |   4 +
 systems/shanghai/default.nix        |   3 +
 3 files changed, 146 insertions(+)
 create mode 100644 modules/extern/nixos/monitoring.nix

diff --git a/modules/extern/nixos/monitoring.nix b/modules/extern/nixos/monitoring.nix
new file mode 100644
index 00000000..8988aa1e
--- /dev/null
+++ b/modules/extern/nixos/monitoring.nix
@@ -0,0 +1,139 @@
+let
+  monitoringModule = {
+    nixosConfig,
+    config,
+    gensokyo-zone,
+    lib,
+    ...
+  }: let
+    inherit (lib.options) mkOption mkEnableOption;
+    inherit (lib.modules) mkIf mkMerge mkDefault mkOptionDefault;
+    inherit (gensokyo-zone.lib) mkAlmostOptionDefault mapOptionDefaults unmerged domain;
+    inherit (nixosConfig.gensokyo-zone) access;
+  in {
+    options = with lib.types; {
+      enable = mkEnableOption "monitoring";
+      systemName = mkOption {
+        type = str;
+        default = nixosConfig.networking.hostName;
+      };
+      node = {
+        enable =
+          mkEnableOption "prometheus.exporters.node"
+          // {
+            default = true;
+          };
+        settings = mkOption {
+          type = unmerged.types.attrs;
+          internal = true;
+        };
+      };
+      promtail = {
+        enable = mkEnableOption "promtail";
+        lokiUrl = mkOption {
+          type = str;
+        };
+        journald = {
+          enable =
+            mkEnableOption "systemd-journald"
+            // {
+              default = true;
+            };
+          settings = mkOption {
+            type = unmerged.types.attrs;
+            internal = true;
+          };
+        };
+        settings = mkOption {
+          type = unmerged.types.attrs;
+          internal = true;
+        };
+      };
+    };
+    config = {
+      node.settings = {
+        enable = mkDefault true;
+        port = mkDefault 9091;
+      };
+      promtail = let
+        cfg = config.promtail;
+      in {
+        lokiUrl = mkMerge [
+          (mkIf access.local.enable (mkDefault "logs.local.${domain}"))
+          (mkIf access.tail.enabled (mkAlmostOptionDefault "logs.tail.${domain}"))
+          (mkOptionDefault (lib.warn "gensokyo-zone.monitoring: promtail needs lan or tailscale access to function" "logs.${domain}"))
+        ];
+        journald.settings = {
+          job_name = "${config.systemName}-journald";
+          journal = {
+            max_age = mkOptionDefault "${toString (24 * 7)}h";
+            labels = mapOptionDefaults {
+              job = "systemd-journald";
+              system = config.systemName;
+              host = nixosConfig.networking.fqdn;
+            };
+          };
+          relabel_configs = [
+            {
+              source_labels = ["__journal__systemd_unit"];
+              target_label = "unit";
+            }
+          ];
+        };
+        settings = {
+          enable = mkDefault true;
+          configuration = {
+            clients = mkOptionDefault [
+              {
+                url = "${cfg.lokiUrl}/loki/api/v1/push";
+              }
+            ];
+            scrape_configs = mkIf cfg.journald.enable [ (unmerged.mergeAttrs cfg.journald.settings) ];
+          };
+        };
+      };
+    };
+  };
+in
+  {
+    config,
+    lib,
+    gensokyo-zone,
+    ...
+  }: let
+    inherit (lib.options) mkOption;
+    inherit (lib.modules) mkIf;
+    inherit (gensokyo-zone.lib) unmerged;
+    cfg = config.gensokyo-zone.monitoring;
+  in {
+    imports = [
+      ./access.nix
+    ];
+
+    options.gensokyo-zone.monitoring = mkOption {
+      type = lib.types.submoduleWith {
+        modules = [monitoringModule];
+        specialArgs = {
+          inherit gensokyo-zone;
+          inherit (gensokyo-zone) inputs;
+          nixosConfig = config;
+        };
+      };
+      default = {};
+    };
+
+    config = {
+      services.promtail = mkIf (cfg.enable && cfg.promtail.enable) (
+        unmerged.mergeAttrs cfg.promtail.settings
+      );
+      services.prometheus.exporters = mkIf cfg.enable {
+        node = mkIf cfg.node.enable (
+          unmerged.mergeAttrs cfg.node.settings
+        );
+      };
+
+      lib.gensokyo-zone.monitoring = {
+        inherit cfg monitoringModule;
+      };
+    };
+  }
diff --git a/systems/extern-test/nixos.nix b/systems/extern-test/nixos.nix
index acbcdcba..fc407134 100644
--- a/systems/extern-test/nixos.nix
+++ b/systems/extern-test/nixos.nix
@@ -29,6 +29,10 @@ in {
       dns = {
         # TODO: enable = true;
       };
+      monitoring = {
+        enable = true;
+        promtail.enable = true;
+      };
       # TODO: users?
     };
 
diff --git a/systems/shanghai/default.nix b/systems/shanghai/default.nix
index 98ea5079..99591ffa 100644
--- a/systems/shanghai/default.nix
+++ b/systems/shanghai/default.nix
@@ -24,4 +24,7 @@ in {
       address6 = "fd7a:115c:a1e0:ab12:4843:cd96:6268:9b7a";
     };
   };
+  exports.services = {
+    prometheus-exporters-node.enable = true;
+  };
 }