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nixpkgs/nixos/modules/services/security/step-ca.nix
2021-11-13 12:40:47 +01:00

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Nix

{ config, lib, pkgs, nixosTests, ... }:
let
cfg = config.services.step-ca;
settingsFormat = (pkgs.formats.json { });
in
{
meta.maintainers = with lib.maintainers; [ mohe2015 ];
options = {
services.step-ca = {
enable = lib.mkEnableOption "the smallstep certificate authority server";
openFirewall = lib.mkEnableOption "opening the certificate authority server port";
package = lib.mkOption {
type = lib.types.package;
default = pkgs.step-ca;
defaultText = lib.literalExpression "pkgs.step-ca";
description = "Which step-ca package to use.";
};
address = lib.mkOption {
type = lib.types.str;
example = "127.0.0.1";
description = ''
The address (without port) the certificate authority should listen at.
This combined with <option>services.step-ca.port</option> overrides <option>services.step-ca.settings.address</option>.
'';
};
port = lib.mkOption {
type = lib.types.port;
example = 8443;
description = ''
The port the certificate authority should listen on.
This combined with <option>services.step-ca.address</option> overrides <option>services.step-ca.settings.address</option>.
'';
};
settings = lib.mkOption {
type = with lib.types; attrsOf anything;
description = ''
Settings that go into <filename>ca.json</filename>. See
<link xlink:href="https://smallstep.com/docs/step-ca/configuration">
the step-ca manual</link> for more information. The easiest way to
configure this module would be to run <literal>step ca init</literal>
to generate <filename>ca.json</filename> and then import it using
<literal>builtins.fromJSON</literal>.
<link xlink:href="https://smallstep.com/docs/step-cli/basic-crypto-operations#run-an-offline-x509-certificate-authority">This article</link>
may also be useful if you want to customize certain aspects of
certificate generation for your CA.
You need to change the database storage path to <filename>/var/lib/step-ca/db</filename>.
<warning>
<para>
The <option>services.step-ca.settings.address</option> option
will be ignored and overwritten by
<option>services.step-ca.address</option> and
<option>services.step-ca.port</option>.
</para>
</warning>
'';
};
intermediatePasswordFile = lib.mkOption {
type = lib.types.path;
example = "/run/keys/smallstep-password";
description = ''
Path to the file containing the password for the intermediate
certificate private key.
<warning>
<para>
Make sure to use a quoted absolute path instead of a path literal
to prevent it from being copied to the globally readable Nix
store.
</para>
</warning>
'';
};
};
};
config = lib.mkIf config.services.step-ca.enable (
let
configFile = settingsFormat.generate "ca.json" (cfg.settings // {
address = cfg.address + ":" + toString cfg.port;
});
in
{
passthru.tests.step-ca = nixosTests.step-ca;
assertions =
[
{
assertion = !lib.isStorePath cfg.intermediatePasswordFile;
message = ''
<option>services.step-ca.intermediatePasswordFile</option> points to
a file in the Nix store. You should use a quoted absolute path to
prevent this.
'';
}
];
systemd.packages = [ cfg.package ];
# configuration file indirection is needed to support reloading
environment.etc."smallstep/ca.json".source = configFile;
systemd.services."step-ca" = {
wantedBy = [ "multi-user.target" ];
restartTriggers = [ configFile ];
unitConfig = {
ConditionFileNotEmpty = ""; # override upstream
};
serviceConfig = {
Environment = "HOME=%S/step-ca";
WorkingDirectory = ""; # override upstream
ReadWriteDirectories = ""; # override upstream
# LocalCredential handles file permission problems arising from the use of DynamicUser.
LoadCredential = "intermediate_password:${cfg.intermediatePasswordFile}";
ExecStart = [
"" # override upstream
"${cfg.package}/bin/step-ca /etc/smallstep/ca.json --password-file \${CREDENTIALS_DIRECTORY}/intermediate_password"
];
# ProtectProc = "invisible"; # not supported by upstream yet
# ProcSubset = "pid"; # not supported by upstream yet
# PrivateUsers = true; # doesn't work with privileged ports therefore not supported by upstream
DynamicUser = true;
StateDirectory = "step-ca";
};
};
networking.firewall = lib.mkIf cfg.openFirewall {
allowedTCPPorts = [ cfg.port ];
};
}
);
}