feat(monitoring): add uptime-kuma for status page, fixes #97

Adds a service for a status page using
[`uptime-kuma`](https://uptime.kuma.pet/).

Open questions here included:
- who could set up the application password (currently a manual step in
services.uptime-kuma), after which the stateless client can be re-built;

flake.lock

@@ -715,6 +715,7 @@
         ],
         "nix-gerrit": "nix-gerrit",
         "nixpkgs": "nixpkgs_2",
+        "stateless-uptime-kuma": "stateless-uptime-kuma",
         "terranix": "terranix"
       }
     },
@@ -763,6 +764,22 @@
         "type": "github"
       }
     },
+    "stateless-uptime-kuma": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1713725430,
+        "narHash": "sha256-e3a4/7bc3GO8/kfFndtDa4/6ob3+XjkOgrN8SfDec8c=",
+        "ref": "refs/heads/master",
+        "rev": "c6baf60295e4bee4e4c13cf5c628ccd3ab89b141",
+        "revCount": 22,
+        "type": "git",
+        "url": "https://git.dgnum.eu/DGNum/stateless-uptime-kuma.git"
+      },
+      "original": {
+        "type": "git",
+        "url": "https://git.dgnum.eu/DGNum/stateless-uptime-kuma.git"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1681028828,

flake.nix

@@ -28,6 +28,9 @@
     channel-scripts.url = "git+https://git.lix.systems/the-distro/channel-scripts.git";
     channel-scripts.inputs.nixpkgs.follows = "nixpkgs";
 
+    stateless-uptime-kuma.url = "git+https://git.dgnum.eu/DGNum/stateless-uptime-kuma.git";
+    stateless-uptime-kuma.flake = false;
+
     lix.follows = "hydra/lix";
 
     grapevine = {
@@ -55,6 +58,7 @@
           inputs.lix.overlays.default
           inputs.nix-gerrit.overlays.default
           inputs.channel-scripts.overlays.default
+          (import "${inputs.stateless-uptime-kuma}/overlay.nix")
         ];
       };
       terraform = pkgs.opentofu;

hosts/public01/default.nix

@@ -9,6 +9,11 @@
   # TODO: make it the default
   networking.domain = "infra.forkos.org";
 
+  bagel.status = {
+    enable = true;
+    domain = "status.forkos.org";
+  };
+
   bagel.sysadmin.enable = true;
   # Newsletter is proxied.
   bagel.raito.v6-proxy-awareness.enable = true;

services/default.nix

@@ -5,6 +5,7 @@
     ./hydra
     ./matrix
     ./monitoring
+    ./uptime-kuma
     ./netbox
     ./ofborg
     ./postgres

services/uptime-kuma/default.nix

@@ -0,0 +1,93 @@
+{
+  inputs,
+  lib,
+  config,
+  ...
+}:
+let
+  cfg = config.bagel.status;
+  # TODO: pull domains from a central place
+  subdomains = [
+    "cl"
+    "netbox"
+    "cache"
+    "grafana"
+    "hydra"
+    "loki"
+    "mimir"
+    "pyroscope"
+    "matrix"
+    "tempo"
+    "amqp"
+    "fodwatch"
+    "git"
+    "alerts"
+    "buildbot"
+    "b"
+    "postgres"
+    "news"
+  ];
+  port = 3001;
+in
+{
+  imports = [ "${inputs.stateless-uptime-kuma}/nixos/module.nix" ];
+
+  options.bagel.status = {
+    enable = lib.mkEnableOption "the status page service (uptime-kuma)";
+    domain = lib.mkOption {
+      type = lib.types.str;
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    services.uptime-kuma.enable = true;
+
+    services.nginx = {
+      enable = true;
+      virtualHosts.${cfg.domain} = {
+        enableACME = true;
+        forceSSL = true;
+        locations."/" = {
+          proxyPass = "http://127.0.0.1:${builtins.toString port}";
+          proxyWebsockets = true;
+        };
+      };
+    };
+
+    networking.firewall.allowedTCPPorts = [
+      80
+      443
+    ];
+
+    statelessUptimeKuma = {
+      probesConfig = {
+        monitors = lib.genAttrs subdomains (name: {
+          type = "http";
+          url = "https://${name}.forkos.org/";
+          tags = [];
+        });
+        status_pages = {
+          "forkos" = {
+            title = "ForkOS";
+            description = "health of the ForkOS infra";
+            showTags = true;
+            publicGroupList = [
+              {
+                name = "Services";
+                weight = 1;
+                monitorList = lib.genAttrs subdomains (id: {
+                  inherit id;
+                });
+              }
+            ];
+          };
+        };
+      };
+      extraFlags = [ "-s" ];
+      host = "http://localhost:${builtins.toString port}/";
+      username = "forkos";
+      passwordFile = config.age.secrets."stateless-uptime-kuma-password".path;
+      enableService = true;
+    };
+  };
+}

terraform/dnsimple.nix

@@ -114,6 +114,7 @@ in
           (record "b" 300 "CNAME" "public01.infra.p.forkos.org")
           (record "postgres" 300 "CNAME" "bagel-box.infra.p.forkos.org")
           (record "news" 3600 "CNAME" "public01.infra.p.forkos.org")
+          (record "status" 3600 "CNAME" "public01.infra.p.forkos.org")
 
           # S3 in delroth's basement
           (record "cache" 300 "AAAA" "2a02:168:6426::12") # smol.delroth.net

terraform/gandi.nix

@@ -88,6 +88,7 @@ in
       (record "b" 300 "CNAME" ["public01.infra.p"])
       (record "postgres" 300 "CNAME" ["bagel-box.infra.p"])
       (record "news" 3600 "CNAME" ["public01.infra.p"])
+      (record "status" 3600 "CNAME" ["public01.infra.p"])
 
       # S3 in delroth's basement
       (record "cache" 300 "AAAA" ["2a02:168:6426::12"]) # smol.delroth.net