nixos/vmalert: init

nixos/doc/manual/release-notes/rl-2305.section.md

···
 
 - [ivpn](https://www.ivpn.net/), a secure, private VPN with fast WireGuard connections. Available as [services.ivpn](#opt-services.ivpn.enable).
 
+- [vmalert](https://victoriametrics.com/), an alerting engine for VictoriaMetrics. Available as [services.vmalert](#opt-services.vmalert.enable).
+
 - [jellyseerr](https://github.com/Fallenbagel/jellyseerr), a web-based requests manager for Jellyfin, forked from Overseerr. Available as [services.jellyseerr](#opt-services.jellyseerr.enable).
 
 - [kavita](https://kavitareader.com), a self-hosted digital library. Available as [services.kavita](options.html#opt-services.kavita.enable).

nixos/modules/module-list.nix

···
   ./services/monitoring/uptime-kuma.nix
   ./services/monitoring/uptime.nix
   ./services/monitoring/vmagent.nix
+  ./services/monitoring/vmalert.nix
   ./services/monitoring/vnstat.nix
   ./services/monitoring/zabbix-agent.nix
   ./services/monitoring/zabbix-proxy.nix

nixos/modules/services/monitoring/vmalert.nix

···
+{ config, pkgs, lib, ... }: with lib;
+let
+  cfg = config.services.vmalert;
+
+  format = pkgs.formats.yaml {};
+
+  confOpts = concatStringsSep " \\\n" (mapAttrsToList mkLine (filterAttrs (_: v: v != false) cfg.settings));
+  confType = with types;
+    let
+      valueType = oneOf [ bool int path str ];
+    in
+    attrsOf (either valueType (listOf valueType));
+
+  mkLine = key: value:
+    if value == true then "-${key}"
+    else if isList value then concatMapStringsSep " " (v: "-${key}=${escapeShellArg (toString v)}") value
+    else "-${key}=${escapeShellArg (toString value)}"
+  ;
+in
+{
+  # interface
+  options.services.vmalert = {
+    enable = mkEnableOption (mdDoc "vmalert");
+
+    package = mkOption {
+      type = types.package;
+      default = pkgs.victoriametrics;
+      defaultText = "pkgs.victoriametrics";
+      description = mdDoc ''
+        The VictoriaMetrics derivation to use.
+      '';
+    };
+
+    settings = mkOption {
+      type = types.submodule {
+        freeformType = confType;
+        options = {
+
+          "datasource.url" = mkOption {
+            type = types.nonEmptyStr;
+            example = "http://localhost:8428";
+            description = mdDoc ''
+              Datasource compatible with Prometheus HTTP API.
+            '';
+          };
+
+          "notifier.url" = mkOption {
+            type = with types; listOf nonEmptyStr;
+            default = [];
+            example = [ "http://127.0.0.1:9093" ];
+            description = mdDoc ''
+              Prometheus Alertmanager URL. List all Alertmanager URLs if it runs in the cluster mode to ensure high availability.
+            '';
+          };
+
+          "rule" = mkOption {
+            type = with types; listOf path;
+            description = mdDoc ''
+              Path to the files with alerting and/or recording rules.
+
+              ::: {.note}
+              Consider using the {option}`services.vmalert.rules` option as a convenient alternative for declaring rules
+              directly in the `nix` language.
+              :::
+            '';
+          };
+
+        };
+      };
+      default = { };
+      example = {
+        "datasource.url" = "http://localhost:8428";
+        "datasource.disableKeepAlive" = true;
+        "datasource.showURL" = false;
+        "rule" = [
+          "http://<some-server-addr>/path/to/rules"
+          "dir/*.yaml"
+        ];
+      };
+      description = mdDoc ''
+        `vmalert` configuration, passed via command line flags. Refer to
+        <https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/README.md#configuration>
+        for details on supported values.
+      '';
+    };
+
+    rules = mkOption {
+      type = format.type;
+      default = {};
+      example = {
+        group = [
+          { name = "TestGroup";
+            rules = [
+              { alert = "ExampleAlertAlwaysFiring";
+                expr = ''
+                  sum by(job)
+                  (up == 1)
+                '';
+              }
+            ];
+          }
+        ];
+      };
+      description = mdDoc ''
+        A list of the given alerting or recording rules against configured `"datasource.url"` compatible with
+        Prometheus HTTP API for `vmalert` to execute. Refer to
+        <https://github.com/VictoriaMetrics/VictoriaMetrics/blob/master/app/vmalert/README.md#rules>
+        for details on supported values.
+      '';
+    };
+  };
+
+  # implementation
+  config = mkIf cfg.enable {
+
+    environment.etc."vmalert/rules.yml".source = format.generate "rules.yml" cfg.rules;
+
+    services.vmalert.settings.rule = [
+      "/etc/vmalert/rules.yml"
+    ];
+
+    systemd.services.vmalert = {
+      description = "vmalert service";
+      wantedBy = [ "multi-user.target" ];
+      after = [ "network.target" ];
+      reloadTriggers = [ config.environment.etc."vmalert/rules.yml".source ];
+
+      serviceConfig = {
+        DynamicUser = true;
+        Restart = "on-failure";
+        ExecStart = "${cfg.package}/bin/vmalert ${confOpts}";
+        ExecReload = ''${pkgs.coreutils}/bin/kill -SIGHUP "$MAINPID"'';
+      };
+    };
+  };
+}