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mcaptcha package and module with nixos tests
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closes #17

Co-authored-by: Shahar "Dawn" Or <[email protected]>
Co-authored-by: Rohit <[email protected]>
Co-authored-by: Matúš Ferech <[email protected]>
Co-authored-by: Alejandro Sanchez Medina <[email protected]>
Co-authored-by: Auguste Baum <[email protected]>
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@jfly @mightyiam
@r0hit05 @matusf @alejandrosame @augustebaum
6 people committed Nov 28, 2023
1 parent f0d36a5 commit 4c1cdbe
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1 change: 1 addition & 0 deletions modules/all-modules.nix
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#liberaforms = import ./liberaforms.nix;
flarum = import ./flarum.nix;
kbin = import ./kbin.nix;
mcaptcha = import ./mcaptcha.nix;
pretalx = import ./pretalx.nix;
unbootable = import ./unbootable.nix;
}
276 changes: 276 additions & 0 deletions modules/mcaptcha.nix
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{
config,
lib,
options,
pkgs,
...
}: let
inherit (lib) types;
cfg = config.services.mcaptcha;
opt = options.services.mcaptcha;
settingsFormat = pkgs.formats.toml {};
filteredSettings = lib.attrsets.filterAttrsRecursive (_path: value: value != null) cfg.settings;
configFile = settingsFormat.generate "mcaptcha.config.toml" filteredSettings;
in {
options.services.mcaptcha.enable = lib.mkEnableOption "mCaptcha server";
options.services.mcaptcha.package = lib.mkPackageOption pkgs "mcaptcha" {};

options.services.mcaptcha.settings = lib.mkOption {
type = lib.types.submodule {
freeformType = settingsFormat.type;

options.database.name = lib.mkOption {
type = types.str;
description = "Applies both when {option}`${opt.database.createLocally}` is set and not.";
default = "mcaptcha";
};

options.database.username = lib.mkOption {
type = types.nullOr types.str;
description = "Ignored when {option}`${opt.database.createLocally}`.";
example = "mcaptcha";
default = null;
};

options.database.hostname = lib.mkOption {
type = types.nullOr types.str;
description = "Ignored when {option}`${opt.database.createLocally}`.";
example = "localhost";
default = null;
};

options.database.port = lib.mkOption {
type = types.nullOr types.port;
description = "Ignored when {option}`${opt.database.createLocally}`.";
example = 5432;
default = null;
};

options.server.port = lib.mkOption {
type = types.port;
description = "Web server port.";
default = 7000;
};

options.server.domain = lib.mkOption {
type = types.str;
description = "Web server host.";
default = "localhost";
example = "example.com";
};

options.server.ip = lib.mkOption {
type = types.str;
description = "Web server addresses to bind to.";
default = "127.0.0.1";
example = "0.0.0.0";
};
};

description = "Extra settings.";
};

options.services.mcaptcha.user = lib.mkOption {
type = types.str;
description = "User account to run under.";
default = "mcaptcha";
};

options.services.mcaptcha.group = lib.mkOption {
type = types.str;
description = "Group for the user mCaptcha runs under.";
default = "mcaptcha";
};

options.services.mcaptcha.database.createLocally = lib.mkOption {
type = types.bool;
description = "Whether to create and use a local database instance";
default = false;
};

options.services.mcaptcha.database.passwordFile = lib.mkOption {
type = types.nullOr types.path;
description = ''
Path to a file containing a database password.
Ignored when {option}`${opt.database.createLocally}`.
'';
default = null;
example = "/run/secrets/mcaptcha/database";
};

options.services.mcaptcha.server.cookieSecretFile = lib.mkOption {
type = types.path;
description = "Path to a file containing a cookie secret.";
example = "/run/secrets/mcaptcha/cookie-secret";
};

options.services.mcaptcha.captcha.saltFile = lib.mkOption {
type = types.path;
description = "Path to a file containing a salt.";
example = "/run/secrets/mcaptcha/salt";
};

options.services.mcaptcha.redis.createLocally = lib.mkOption {
type = types.bool;
description = "Whether to create a Redis instance locally.";
default = false;
};

options.services.mcaptcha.redis.host = lib.mkOption {
type = types.str;
description = "Ignored when {option}`${opt.redis.createLocally}`.";
example = "redis.example.com";
};

options.services.mcaptcha.redis.port = lib.mkOption {
type = types.port;
description = "Applies both when {option}`${opt.redis.createLocally}` is set and not.";
default = 6379;
};

options.services.mcaptcha.redis.user = lib.mkOption {
type = types.str;
description = "Ignored when {option}`${opt.redis.createLocally}`.";
default = "default";
example = "mcaptcha";
};

options.services.mcaptcha.redis.passwordFile = lib.mkOption {
type = types.path;
description = ''
Path to a file containing the Redis server password.
Ignored when {option}`${opt.redis.createLocally}`.";
'';
example = "/run/secrets/mcaptcha/redis-secret";
};

config = lib.mkIf cfg.enable {
assertions = [
{
assertion = (!cfg.database.createLocally) -> (cfg.settings.database.username != null);
message = "If `${opt.database.createLocally}` is not specified, then `${opt.settings.database.username}` must be specified";
}
{
assertion = (!cfg.database.createLocally) -> (cfg.settings.database.port != null);
message = "If `${opt.database.createLocally}` is not specified, then `${opt.settings.database.port}` must be specified";
}
{
assertion = (!cfg.database.createLocally) -> (cfg.settings.database.hostname != null);
message = "If `${opt.database.createLocally}` is not specified, then `${opt.settings.database.hostname}` must be specified";
}
];
services.mcaptcha.settings = {
# mCaptcha has no support for defaults. Every option must be specified.
# The module-provided defaults below are based on
# https://github.com/mCaptcha/mCaptcha/blob/f337ee0643d88723776e1de4e5588dfdb6c0c574/config/default.toml
debug = lib.mkDefault false;
source_code = lib.mkDefault "https://github.com/mCaptcha/mCaptcha";
commercial = lib.mkDefault false;
allow_demo = lib.mkDefault false;
allow_registration = lib.mkDefault true;

server = {
proxy_has_tls = lib.mkDefault false;
};

database = {
pool = lib.mkDefault 4;
database_type = lib.mkDefault "postgres";
};

captcha = {
gc = lib.mkDefault 30;
runners = lib.mkDefault 4;
queue_length = lib.mkDefault 2000;
enable_stats = lib.mkDefault true;

default_difficulty_strategy = {
avg_traffic_difficulty = lib.mkDefault 50000;
peak_sustainable_traffic_difficulty = lib.mkDefault 3000000;
broke_my_site_traffic_difficulty = lib.mkDefault 5000000;
duration = lib.mkDefault 30;
};
};

redis = {
pool = lib.mkDefault 4;
};
};

systemd.services.mcaptcha.description = "mCaptcha: a CAPTCHA system that gives attackers a run for their money";

systemd.services.mcaptcha.script = let
serverCookieSecret = "export MCAPTCHA_SERVER_COOKIE_SECRET=$(< ${cfg.server.cookieSecretFile})";
captchaSalt = "export MCAPTCHA_CAPTCHA_SALT=$(< ${cfg.captcha.saltFile})";
databaseLocalUrl = ''export DATABASE_URL="postgres:///${cfg.settings.database.name}?host=/run/postgresql"'';
databasePassword = "export MCAPTCHA_DATABASE_PASSWORD=$(< ${cfg.database.passwordFile})";
redisLocalUrl = ''export MCAPTCHA_REDIS_URL="redis://${cfg.redis.host}:${builtins.toString cfg.redis.port}"'';
redisRemoteUrl = let
urlencode = lib.getExe' pkgs.urlencode "urlencode";
in ''
redis_user=$(${urlencode} -e userinfo ${lib.escapeShellArg cfg.redis.user})
redis_pass=$(${urlencode} -e userinfo < ${cfg.redis.passwordFile})
export MCAPTCHA_REDIS_URL="redis://$redis_user:$redis_pass@${cfg.redis.host}:${builtins.toString cfg.redis.port}"
'';
exec = "exec ${lib.getExe cfg.package}";
in
lib.concatStringsSep "\n" [
serverCookieSecret
captchaSalt
(
if cfg.database.createLocally
then databaseLocalUrl
else databasePassword
)
(
if cfg.redis.createLocally
then redisLocalUrl
else redisRemoteUrl
)
exec
];

systemd.services.mcaptcha.environment.MCAPTCHA_CONFIG = builtins.toString configFile;
systemd.services.mcaptcha.after = ["syslog.target"] ++ lib.optionals cfg.database.createLocally ["postgresql.service"];
systemd.services.mcaptcha.bindsTo = lib.optionals cfg.database.createLocally ["postgresql.service"];
systemd.services.mcaptcha.wants = ["network-online.target"];
systemd.services.mcaptcha.wantedBy = ["multi-user.target"];
# Settings modeled after https://github.com/mCaptcha/mCaptcha/blob/f337ee0643d88723776e1de4e5588dfdb6c0c574/docs/DEPLOYMENT.md#6-systemd-service-configuration
systemd.services.mcaptcha.serviceConfig.User = cfg.user;
systemd.services.mcaptcha.serviceConfig.Type = "simple";
systemd.services.mcaptcha.serviceConfig.Restart = "on-failure";
systemd.services.mcaptcha.serviceConfig.RestartSec = 1;
systemd.services.mcaptcha.serviceConfig.SuccessExitStatus = "3 4";
systemd.services.mcaptcha.serviceConfig.RestartForceExitStatus = "3 4";
systemd.services.mcaptcha.serviceConfig.SystemCallArchitectures = "native";
systemd.services.mcaptcha.serviceConfig.MemoryDenyWriteExecute = true;
systemd.services.mcaptcha.serviceConfig.NoNewPrivileges = true;
services.mcaptcha.redis.host = lib.mkIf cfg.redis.createLocally "127.0.0.1";

users.users."${cfg.user}" = {
isSystemUser = true;
group = cfg.group;
};

users.groups."${cfg.group}" = {};

services.postgresql = lib.mkIf cfg.database.createLocally {
enable = true;
ensureDatabases = [cfg.settings.database.name];
ensureUsers = [
{
name = cfg.user;
ensurePermissions = {"DATABASE ${cfg.settings.database.name}" = "ALL PRIVILEGES";};
}
];
};

services.redis.servers.mcaptcha = lib.mkIf cfg.redis.createLocally {
enable = true;
port = cfg.redis.port;
extraParams = ["--loadmodule" "${pkgs.mcaptcha-cache}/lib/libcache.so"];
};
};
}
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