xin/monitoring/default.nix

{ config
, lib
, ...
}:
with lib; let
  cfg = config.services.xin-monitoring;
  inherit
    (builtins)
    readFile
    concatStringsSep
    attrValues
    mapAttrs
    replaceStrings
    ;

  nginxCfg = config.services.nginx;
  buildFSChecker = fsList: (concatStringsSep "\n" (attrValues (mapAttrs
    (f: v:
      if v.fsType != "sshfs"
      then ''
        check filesystem ${replaceStrings ["/"] ["_"] f} with path ${f}
           if space usage > 90% then alert
           if inode usage > 90% then alert
      ''
      else "")
    fsList)));
  buildNginxChecker = vhostList: (concatStringsSep "\n" (attrValues (mapAttrs
    (f: v: ''
      check host ${f} with address ${f}
          if failed port 80 protocol http then alert
          ${
        if v.enableACME
        then "if failed port 443 protocol https then alert"
        else ""
      }
    '')
    vhostList)));
  nginxChecks =
    if nginxCfg.enable
    then
      if config.networking.hostName == "h"
      then (buildNginxChecker nginxCfg.virtualHosts)
      else ""
    else "";
in
{
  options = {
    services.xin-monitoring = {
      enable = mkOption {
        type = types.bool;
        default = true;
        description = "Enable Monitoring";
      };
      fs = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Create monitoring entry points from `config.fileSystems`.
        '';
      };
      nginx = mkOption {
        type = types.bool;
        default = false;
        description = ''
          Create monitoring entry points from `services.nginx.virtualHosts`.
        '';
      };
    };
  };
  config = mkIf cfg.enable {
    sops.secrets = {
      monit_cfg = {
        sopsFile = config.xin-secrets.deploy;
        owner = "root";
        mode = "400";
      };
    };
    services.monit = {
      enable = true;
      config = concatStrings [
        (readFile ./monitrc)
        (optionalString cfg.fs (buildFSChecker config.fileSystems))
        (optionalString cfg.nginx nginxChecks)
      ];
    };
  };
}