services/prometheus: collect ping metrics in enthalpy network

nixos/hosts/kanako-hkg0/default.nix

@@ -10,6 +10,7 @@
     ++ (with profiles; [
       services.caddy
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");
 

nixos/hosts/reisen-fra0/default.nix

@@ -10,6 +10,7 @@
     ++ (with profiles; [
       services.caddy
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");
 

nixos/hosts/reisen-nrt0/default.nix

@@ -12,6 +12,7 @@
       services.knot.secondary
       services.ntfy
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
       services.prometheus.server
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");

nixos/hosts/reisen-sea0/default.nix

@@ -11,6 +11,7 @@
       services.caddy
       services.knot.primary
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");
 

nixos/hosts/reisen-sin0/default.nix

@@ -11,6 +11,7 @@
       services.caddy
       services.knot.secondary
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");
 

nixos/hosts/suwako-vie0/default.nix

@@ -20,6 +20,7 @@
       services.miniflux
       services.postgresql
       services.prometheus.node-exporter
+      services.prometheus.ping-exporter
       services.well-known
     ])
     ++ (mylib.path.scanPaths ./. "default.nix");

nixos/modules/networking/ports.nix

@@ -34,6 +34,7 @@ in
       prometheus-alertmanager = 4061;
       prometheus-node-exporter = 4070;
       prometheus-blackbox-exporter = 4071;
+      prometheus-ping-exporter = 4072;
 
       # public ports
       enthalpy-wireguard-reimu-aston = 13101;

nixos/profiles/services/prometheus/ping-exporter.nix

@@ -0,0 +1,46 @@
+{
+  config,
+  lib,
+  ...
+}:
+let
+  common = import ../../../../zones/common.nix;
+  enthalpyHosts = lib.filterAttrs (_name: value: value.enthalpy_node_address != null) common.hosts;
+  targets = lib.mapAttrsToList (name: _value: "${name}.enta.rebmit.link") enthalpyHosts;
+in
+{
+  services.prometheus.exporters.ping = {
+    enable = true;
+    listenAddress = "127.0.0.1";
+    port = config.networking.ports.prometheus-ping-exporter;
+    telemetryPath = "/ping";
+    settings = {
+      inherit targets;
+    };
+  };
+
+  systemd.services.prometheus-ping-exporter = {
+    inherit (config.networking.netns.enthalpy) serviceConfig;
+    after = [ "netns-enthalpy.service" ];
+    partOf = [ "netns-enthalpy.service" ];
+    wantedBy = [ "netns-enthalpy.service" ];
+  };
+
+  networking.netns.default.forwardPorts = lib.singleton {
+    protocol = "tcp";
+    netns = "enthalpy";
+    source = "127.0.0.1:${toString config.networking.ports.prometheus-ping-exporter}";
+    target = "127.0.0.1:${toString config.networking.ports.prometheus-ping-exporter}";
+  };
+
+  services.caddy.virtualHosts."${config.networking.fqdn}" = {
+    extraConfig = with config.services.prometheus.exporters.ping; ''
+      route /ping {
+        basic_auth {
+          prometheus {$PROM_PASSWD}
+        }
+        reverse_proxy ${listenAddress}:${toString port}
+      }
+    '';
+  };
+}

nixos/profiles/services/prometheus/server.nix

@@ -74,6 +74,16 @@ in
         };
         static_configs = [ { inherit targets; } ];
       }
+      {
+        job_name = "ping";
+        scheme = "https";
+        metrics_path = "/ping";
+        basic_auth = {
+          username = "prometheus";
+          password_file = config.sops.secrets."prometheus/password".path;
+        };
+        static_configs = [ { inherit targets; } ];
+      }
       {
         job_name = "dns";
         scheme = "http";