2 files changed, 117 insertions, 0 deletions
diff --git a/krebs/3modules/default.nix b/krebs/3modules/default.nix
index e0810ab63..f336c966f 100644
--- a/krebs/3modules/default.nix
+++ b/krebs/3modules/default.nix
@@ -22,6 +22,7 @@ let
       ./go.nix
       ./iptables.nix
       ./kapacitor.nix
+      ./monit.nix
       ./newsbot-js.nix
       ./nginx.nix
       ./nixpkgs.nix
diff --git a/krebs/3modules/monit.nix b/krebs/3modules/monit.nix
new file mode 100644
index 000000000..5191a1754
--- /dev/null
+++ b/krebs/3modules/monit.nix
@@ -0,0 +1,116 @@
+{ config, lib, pkgs, ... }:
+
+with builtins;
+with import <stockholm/lib>;
+
+let
+  cfg = config.krebs.monit;
+
+  out = {
+    options.krebs.monit = api;
+    config = mkIf cfg.enable imp;
+  };
+
+  api = {
+    enable = mkEnableOption "monit";
+    http = {
+      enable = mkEnableOption "monit http server";
+      port = mkOption {
+        type = types.int;
+        default = 9093;
+      };
+      user = mkOption {
+        type = types.str;
+        default = "krebs";
+      };
+      pass = mkOption {
+        type = types.str;
+        default = "bob";
+      };
+    };
+    user = mkOption {
+      type = types.user;
+      default = {
+        name = "monit";
+      };
+    };
+    group = mkOption {
+      type = types.group;
+      default = {
+        name = "monitor";
+      };
+    };
+    extraConfig = mkOption {
+      type = types.attrs;
+      default = {};
+    };
+    alarms = mkOption {
+      default = {};
+      type = with types; attrsOf (submodule {
+        options = {
+          test = mkOption {
+            type = path;
+          };
+          alarm = mkOption {
+            type = path;
+          };
+          interval = mkOption {
+            type = str;
+            default = "10";
+          };
+        };
+      });
+    };
+  };
+
+  imp = let
+    configFile = pkgs.writeText "monit.cfg" ''
+      ${optionalString cfg.http.enable ''
+        set httpd port ${toString cfg.http.port}
+          allow ${cfg.http.user}:${cfg.http.pass}
+      ''}
+      set daemon 10
+
+      ${concatStringsSep "\n" (mapAttrsToList (name: alarm: ''
+        check program ${name} with path "${alarm.test}"
+          every 10 cycles
+          if status != 0 then exec "${alarm.alarm}"
+      '') cfg.alarms)}
+    '';
+  in {
+    environment.etc = [
+      {
+        source = configFile;
+        target = "monit.conf";
+        mode = "0400";
+        uid = config.users.users.${cfg.user.name}.uid;
+      }
+    ];
+    users = {
+      groups.${cfg.group.name} = {
+        inherit (cfg.group) name gid;
+      };
+      users.${cfg.user.name} = {
+        inherit (cfg.user) home name uid;
+        createHome = true;
+        group = cfg.group.name;
+      };
+    };
+
+    systemd.services.monit = {
+      description = "monit";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+
+      restartIfChanged = true;
+
+      serviceConfig = {
+        Restart = "always";
+        User = cfg.user.name;
+        ExecStart = "${pkgs.monit}/bin/monit -I -c /etc/monit.conf";
+        # Monit should restart when the config changes
+        ExecStartPre = "${pkgs.coreutils}/bin/echo ${configFile}";
+      };
+    };
+  };
+in out