summary refs log tree commit diff
path: root/nixos/modules/services/networking/nomad.nix
blob: dafdae0c327b908f01952acc0e94f61ce435e125 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
{ config, lib, pkgs, ... }:
with lib;
let
  cfg = config.services.nomad;
  format = pkgs.formats.json { };
in
{
  ##### interface
  options = {
    services.nomad = {
      enable = mkEnableOption "Nomad, a distributed, highly available, datacenter-aware scheduler";

      package = mkOption {
        type = types.package;
        default = pkgs.nomad;
        defaultText = "pkgs.nomad";
        description = ''
          The package used for the Nomad agent and CLI.
        '';
      };

      extraPackages = mkOption {
        type = types.listOf types.package;
        default = [ ];
        description = ''
          Extra packages to add to <envar>PATH</envar> for the Nomad agent process.
        '';
        example = literalExample ''
          with pkgs; [ cni-plugins ]
        '';
      };

      dropPrivileges = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Whether the nomad agent should be run as a non-root nomad user.
        '';
      };

      enableDocker = mkOption {
        type = types.bool;
        default = true;
        description = ''
          Enable Docker support. Needed for Nomad's docker driver.

          Note that the docker group membership is effectively equivalent
          to being root, see https://github.com/moby/moby/issues/9976.
        '';
      };

      extraSettingsPaths = mkOption {
        type = types.listOf types.path;
        default = [];
        description = ''
          Additional settings paths used to configure nomad. These can be files or directories.
        '';
        example = literalExample ''
          [ "/etc/nomad-mutable.json" "/run/keys/nomad-with-secrets.json" "/etc/nomad/config.d" ]
        '';
      };

      settings = mkOption {
        type = format.type;
        default = {};
        description = ''
          Configuration for Nomad. See the <link xlink:href="https://www.nomadproject.io/docs/configuration">documentation</link>
          for supported values.
        '';
        example = literalExample ''
          {
            # A minimal config example:
            server = {
              enabled = true;
              bootstrap_expect = 1; # for demo; no fault tolerance
            };
            client = {
              enabled = true;
            };
          }
        '';
      };
    };
  };

  ##### implementation
  config = mkIf cfg.enable {
    services.nomad.settings = {
      # Agrees with `StateDirectory = "nomad"` set below.
      data_dir = mkDefault "/var/lib/nomad";
    };

    environment = {
      etc."nomad.json".source = format.generate "nomad.json" cfg.settings;
      systemPackages = [ cfg.package ];
    };

    systemd.services.nomad = {
      description = "Nomad";
      wantedBy = [ "multi-user.target" ];
      wants = [ "network-online.target" ];
      after = [ "network-online.target" ];
      restartTriggers = [ config.environment.etc."nomad.json".source ];

      path = cfg.extraPackages ++ (with pkgs; [
        # Client mode requires at least the following:
        coreutils
        iproute
        iptables
      ]);

      serviceConfig = {
        DynamicUser = cfg.dropPrivileges;
        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
        ExecStart = "${cfg.package}/bin/nomad agent -config=/etc/nomad.json" +
          concatMapStrings (path: " -config=${path}") cfg.extraSettingsPaths;
        KillMode = "process";
        KillSignal = "SIGINT";
        LimitNOFILE = 65536;
        LimitNPROC = "infinity";
        OOMScoreAdjust = -1000;
        Restart = "on-failure";
        RestartSec = 2;
        # Agrees with the default `data_dir = "/var/lib/nomad"` in `settings` above.
        StateDirectory = "nomad";
        TasksMax = "infinity";
        User = optionalString cfg.dropPrivileges "nomad";
      } // (optionalAttrs cfg.enableDocker {
        SupplementaryGroups = "docker"; # space-separated string
      });

      unitConfig = {
        StartLimitIntervalSec = 10;
        StartLimitBurst = 3;
      };
    };

    # Docker support requires the Docker daemon to be running.
    virtualisation.docker.enable = mkIf cfg.enableDocker true;
  };
}