af5765b0dc
nixos/acme: improve some descriptions
478 lines
20 KiB
Nix
478 lines
20 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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cfg = config.security.acme;
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certOpts = { name, ... }: {
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options = {
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webroot = mkOption {
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type = types.nullOr types.str;
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default = null;
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example = "/var/lib/acme/acme-challenges";
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description = ''
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Where the webroot of the HTTP vhost is located.
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<filename>.well-known/acme-challenge/</filename> directory
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will be created below the webroot if it doesn't exist.
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<literal>http://example.org/.well-known/acme-challenge/</literal> must also
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be available (notice unencrypted HTTP).
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'';
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};
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server = mkOption {
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type = types.nullOr types.str;
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default = null;
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description = ''
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ACME Directory Resource URI. Defaults to Let's Encrypt's
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production endpoint,
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<link xlink:href="https://acme-v02.api.letsencrypt.org/directory"/>, if unset.
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'';
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};
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domain = mkOption {
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type = types.str;
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default = name;
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description = "Domain to fetch certificate for (defaults to the entry name).";
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};
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email = mkOption {
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type = types.nullOr types.str;
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default = cfg.email;
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description = "Contact email address for the CA to be able to reach you.";
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};
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user = mkOption {
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type = types.str;
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default = "root";
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description = "User running the ACME client.";
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};
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group = mkOption {
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type = types.str;
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default = "root";
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description = "Group running the ACME client.";
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};
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allowKeysForGroup = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Give read permissions to the specified group
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(<option>security.acme.cert.<name>.group</option>) to read SSL private certificates.
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'';
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};
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postRun = mkOption {
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type = types.lines;
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default = "";
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example = "systemctl reload nginx.service";
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description = ''
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Commands to run after new certificates go live. Typically
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the web server and other servers using certificates need to
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be reloaded.
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Executed in the same directory with the new certificate.
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'';
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};
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directory = mkOption {
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type = types.str;
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readOnly = true;
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default = "/var/lib/acme/${name}";
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description = "Directory where certificate and other state is stored.";
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};
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extraDomains = mkOption {
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type = types.attrsOf (types.nullOr types.str);
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default = {};
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example = literalExample ''
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{
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"example.org" = null;
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"mydomain.org" = null;
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}
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'';
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description = ''
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A list of extra domain names, which are included in the one certificate to be issued.
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Setting a distinct server root is deprecated and not functional in 20.03+
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'';
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};
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keyType = mkOption {
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type = types.str;
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default = "ec256";
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description = ''
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Key type to use for private keys.
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For an up to date list of supported values check the --key-type option
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at <link xlink:href="https://go-acme.github.io/lego/usage/cli/#usage"/>.
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'';
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};
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dnsProvider = mkOption {
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type = types.nullOr types.str;
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default = null;
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example = "route53";
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description = ''
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DNS Challenge provider. For a list of supported providers, see the "code"
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field of the DNS providers listed at <link xlink:href="https://go-acme.github.io/lego/dns/"/>.
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'';
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};
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credentialsFile = mkOption {
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type = types.path;
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description = ''
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Path to an EnvironmentFile for the cert's service containing any required and
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optional environment variables for your selected dnsProvider.
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To find out what values you need to set, consult the documentation at
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<link xlink:href="https://go-acme.github.io/lego/dns/"/> for the corresponding dnsProvider.
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'';
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example = "/var/src/secrets/example.org-route53-api-token";
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};
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dnsPropagationCheck = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Toggles lego DNS propagation check, which is used alongside DNS-01
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challenge to ensure the DNS entries required are available.
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'';
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};
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ocspMustStaple = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Turns on the OCSP Must-Staple TLS extension.
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Make sure you know what you're doing! See:
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<itemizedlist>
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<listitem><para><link xlink:href="https://blog.apnic.net/2019/01/15/is-the-web-ready-for-ocsp-must-staple/" /></para></listitem>
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<listitem><para><link xlink:href="https://blog.hboeck.de/archives/886-The-Problem-with-OCSP-Stapling-and-Must-Staple-and-why-Certificate-Revocation-is-still-broken.html" /></para></listitem>
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</itemizedlist>
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'';
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};
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extraLegoRenewFlags = mkOption {
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type = types.listOf types.str;
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default = [];
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description = ''
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Additional flags to pass to lego renew.
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'';
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};
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};
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};
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in
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{
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###### interface
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imports = [
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(mkRemovedOptionModule [ "security" "acme" "production" ] ''
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Use security.acme.server to define your staging ACME server URL instead.
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To use Let's Encrypt's staging server, use security.acme.server =
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"https://acme-staging-v02.api.letsencrypt.org/directory".
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''
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)
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(mkRemovedOptionModule [ "security" "acme" "directory"] "ACME Directory is now hardcoded to /var/lib/acme and its permisisons are managed by systemd. See https://github.com/NixOS/nixpkgs/issues/53852 for more info.")
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(mkRemovedOptionModule [ "security" "acme" "preDelay"] "This option has been removed. If you want to make sure that something executes before certificates are provisioned, add a RequiredBy=acme-\${cert}.service to the service you want to execute before the cert renewal")
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(mkRemovedOptionModule [ "security" "acme" "activationDelay"] "This option has been removed. If you want to make sure that something executes before certificates are provisioned, add a RequiredBy=acme-\${cert}.service to the service you want to execute before the cert renewal")
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(mkChangedOptionModule [ "security" "acme" "validMin"] [ "security" "acme" "validMinDays"] (config: config.security.acme.validMin / (24 * 3600)))
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];
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options = {
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security.acme = {
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validMinDays = mkOption {
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type = types.int;
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default = 30;
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description = "Minimum remaining validity before renewal in days.";
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};
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email = mkOption {
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type = types.nullOr types.str;
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default = null;
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description = "Contact email address for the CA to be able to reach you.";
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};
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renewInterval = mkOption {
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type = types.str;
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default = "daily";
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description = ''
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Systemd calendar expression when to check for renewal. See
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<citerefentry><refentrytitle>systemd.time</refentrytitle>
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<manvolnum>7</manvolnum></citerefentry>.
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'';
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};
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server = mkOption {
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type = types.nullOr types.str;
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default = null;
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description = ''
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ACME Directory Resource URI. Defaults to Let's Encrypt's
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production endpoint,
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<link xlink:href="https://acme-v02.api.letsencrypt.org/directory"/>, if unset.
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'';
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};
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preliminarySelfsigned = mkOption {
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type = types.bool;
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default = true;
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description = ''
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Whether a preliminary self-signed certificate should be generated before
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doing ACME requests. This can be useful when certificates are required in
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a webserver, but ACME needs the webserver to make its requests.
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With preliminary self-signed certificate the webserver can be started and
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can later reload the correct ACME certificates.
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'';
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};
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acceptTerms = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Accept the CA's terms of service. The default provider is Let's Encrypt,
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you can find their ToS at <link xlink:href="https://letsencrypt.org/repository/"/>.
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'';
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};
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certs = mkOption {
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default = { };
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type = with types; attrsOf (submodule certOpts);
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description = ''
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Attribute set of certificates to get signed and renewed. Creates
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<literal>acme-''${cert}.{service,timer}</literal> systemd units for
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each certificate defined here. Other services can add dependencies
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to those units if they rely on the certificates being present,
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or trigger restarts of the service if certificates get renewed.
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'';
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example = literalExample ''
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{
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"example.com" = {
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webroot = "/var/www/challenges/";
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email = "foo@example.com";
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extraDomains = { "www.example.com" = null; "foo.example.com" = null; };
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};
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"bar.example.com" = {
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webroot = "/var/www/challenges/";
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email = "bar@example.com";
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};
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}
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'';
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};
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};
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};
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###### implementation
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config = mkMerge [
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(mkIf (cfg.certs != { }) {
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assertions = let
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certs = (mapAttrsToList (k: v: v) cfg.certs);
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in [
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{
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assertion = all (certOpts: certOpts.dnsProvider == null || certOpts.webroot == null) certs;
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message = ''
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Options `security.acme.certs.<name>.dnsProvider` and
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`security.acme.certs.<name>.webroot` are mutually exclusive.
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'';
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}
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{
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assertion = cfg.email != null || all (certOpts: certOpts.email != null) certs;
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message = ''
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You must define `security.acme.certs.<name>.email` or
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`security.acme.email` to register with the CA.
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'';
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}
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{
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assertion = cfg.acceptTerms;
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message = ''
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You must accept the CA's terms of service before using
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the ACME module by setting `security.acme.acceptTerms`
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to `true`. For Let's Encrypt's ToS see https://letsencrypt.org/repository/
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'';
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}
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];
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systemd.services = let
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services = concatLists servicesLists;
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servicesLists = mapAttrsToList certToServices cfg.certs;
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certToServices = cert: data:
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let
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# StateDirectory must be relative, and will be created under /var/lib by systemd
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lpath = "acme/${cert}";
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apath = "/var/lib/${lpath}";
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spath = "/var/lib/acme/.lego/${cert}";
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keyName = builtins.replaceStrings ["*"] ["_"] data.domain;
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requestedDomains = pipe ([ data.domain ] ++ (attrNames data.extraDomains)) [
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(domains: sort builtins.lessThan domains)
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(domains: concatStringsSep "," domains)
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];
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fileMode = if data.allowKeysForGroup then "640" else "600";
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globalOpts = [ "-d" data.domain "--email" data.email "--path" "." "--key-type" data.keyType ]
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++ optionals (cfg.acceptTerms) [ "--accept-tos" ]
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++ optionals (data.dnsProvider != null && !data.dnsPropagationCheck) [ "--dns.disable-cp" ]
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++ concatLists (mapAttrsToList (name: root: [ "-d" name ]) data.extraDomains)
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++ (if data.dnsProvider != null then [ "--dns" data.dnsProvider ] else [ "--http" "--http.webroot" data.webroot ])
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++ optionals (cfg.server != null || data.server != null) ["--server" (if data.server == null then cfg.server else data.server)];
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certOpts = optionals data.ocspMustStaple [ "--must-staple" ];
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runOpts = escapeShellArgs (globalOpts ++ [ "run" ] ++ certOpts);
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renewOpts = escapeShellArgs (globalOpts ++
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[ "renew" "--days" (toString cfg.validMinDays) ] ++
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certOpts ++ data.extraLegoRenewFlags);
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acmeService = {
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description = "Renew ACME Certificate for ${cert}";
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path = with pkgs; [ openssl ];
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after = [ "network.target" "network-online.target" ];
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wants = [ "network-online.target" ];
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wantedBy = mkIf (!config.boot.isContainer) [ "multi-user.target" ];
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serviceConfig = {
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Type = "oneshot";
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User = data.user;
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Group = data.group;
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PrivateTmp = true;
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StateDirectory = "acme/.lego/${cert} acme/.lego/accounts ${lpath}";
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StateDirectoryMode = if data.allowKeysForGroup then "750" else "700";
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WorkingDirectory = spath;
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# Only try loading the credentialsFile if the dns challenge is enabled
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EnvironmentFile = if data.dnsProvider != null then data.credentialsFile else null;
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ExecStart = pkgs.writeScript "acme-start" ''
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#!${pkgs.runtimeShell} -e
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test -L ${spath}/accounts -o -d ${spath}/accounts || ln -s ../accounts ${spath}/accounts
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LEGO_ARGS=(${runOpts})
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if [ -e ${spath}/certificates/${keyName}.crt ]; then
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REQUESTED_DOMAINS="${requestedDomains}"
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EXISTING_DOMAINS="$(openssl x509 -in ${spath}/certificates/${keyName}.crt -noout -ext subjectAltName | tail -n1 | sed -e 's/ *DNS://g')"
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if [ "''${REQUESTED_DOMAINS}" == "''${EXISTING_DOMAINS}" ]; then
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LEGO_ARGS=(${renewOpts})
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fi
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fi
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${pkgs.lego}/bin/lego ''${LEGO_ARGS[@]}
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'';
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ExecStartPost =
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let
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script = pkgs.writeScript "acme-post-start" ''
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#!${pkgs.runtimeShell} -e
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cd ${apath}
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# Test that existing cert is older than new cert
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KEY=${spath}/certificates/${keyName}.key
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KEY_CHANGED=no
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if [ -e $KEY -a $KEY -nt key.pem ]; then
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KEY_CHANGED=yes
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cp -p ${spath}/certificates/${keyName}.key key.pem
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cp -p ${spath}/certificates/${keyName}.crt fullchain.pem
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cp -p ${spath}/certificates/${keyName}.issuer.crt chain.pem
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ln -sf fullchain.pem cert.pem
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cat key.pem fullchain.pem > full.pem
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fi
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chmod ${fileMode} *.pem
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chown '${data.user}:${data.group}' *.pem
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if [ "$KEY_CHANGED" = "yes" ]; then
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: # noop in case postRun is empty
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${data.postRun}
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fi
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'';
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in
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"+${script}";
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};
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};
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selfsignedService = {
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description = "Create preliminary self-signed certificate for ${cert}";
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path = [ pkgs.openssl ];
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script =
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''
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workdir="$(mktemp -d)"
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# Create CA
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openssl genrsa -des3 -passout pass:xxxx -out $workdir/ca.pass.key 2048
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openssl rsa -passin pass:xxxx -in $workdir/ca.pass.key -out $workdir/ca.key
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openssl req -new -key $workdir/ca.key -out $workdir/ca.csr \
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-subj "/C=UK/ST=Warwickshire/L=Leamington/O=OrgName/OU=Security Department/CN=example.com"
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openssl x509 -req -days 1 -in $workdir/ca.csr -signkey $workdir/ca.key -out $workdir/ca.crt
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# Create key
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openssl genrsa -des3 -passout pass:xxxx -out $workdir/server.pass.key 2048
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openssl rsa -passin pass:xxxx -in $workdir/server.pass.key -out $workdir/server.key
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openssl req -new -key $workdir/server.key -out $workdir/server.csr \
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-subj "/C=UK/ST=Warwickshire/L=Leamington/O=OrgName/OU=IT Department/CN=example.com"
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openssl x509 -req -days 1 -in $workdir/server.csr -CA $workdir/ca.crt \
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-CAkey $workdir/ca.key -CAserial $workdir/ca.srl -CAcreateserial \
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-out $workdir/server.crt
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# Copy key to destination
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cp $workdir/server.key ${apath}/key.pem
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# Create fullchain.pem (same format as "simp_le ... -f fullchain.pem" creates)
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cat $workdir/{server.crt,ca.crt} > "${apath}/fullchain.pem"
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# Create full.pem for e.g. lighttpd
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cat $workdir/{server.key,server.crt,ca.crt} > "${apath}/full.pem"
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# Give key acme permissions
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chown '${data.user}:${data.group}' "${apath}/"{key,fullchain,full}.pem
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chmod ${fileMode} "${apath}/"{key,fullchain,full}.pem
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'';
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serviceConfig = {
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Type = "oneshot";
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PrivateTmp = true;
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StateDirectory = lpath;
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User = data.user;
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Group = data.group;
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};
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unitConfig = {
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# Do not create self-signed key when key already exists
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ConditionPathExists = "!${apath}/key.pem";
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};
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};
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in (
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[ { name = "acme-${cert}"; value = acmeService; } ]
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++ optional cfg.preliminarySelfsigned { name = "acme-selfsigned-${cert}"; value = selfsignedService; }
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);
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servicesAttr = listToAttrs services;
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in
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servicesAttr;
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systemd.tmpfiles.rules =
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map (data: "d ${data.webroot}/.well-known/acme-challenge - ${data.user} ${data.group}") (filter (data: data.webroot != null) (attrValues cfg.certs));
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systemd.timers = let
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# Allow systemd to pick a convenient time within the day
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# to run the check.
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# This allows the coalescing of multiple timer jobs.
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# We divide by the number of certificates so that if you
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# have many certificates, the renewals are distributed over
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# the course of the day to avoid rate limits.
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numCerts = length (attrNames cfg.certs);
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_24hSecs = 60 * 60 * 24;
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AccuracySec = "${toString (_24hSecs / numCerts)}s";
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in flip mapAttrs' cfg.certs (cert: data: nameValuePair
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("acme-${cert}")
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({
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description = "Renew ACME Certificate for ${cert}";
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wantedBy = [ "timers.target" ];
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timerConfig = {
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OnCalendar = cfg.renewInterval;
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Unit = "acme-${cert}.service";
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Persistent = "yes";
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inherit AccuracySec;
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# Skew randomly within the day, per https://letsencrypt.org/docs/integration-guide/.
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RandomizedDelaySec = "24h";
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};
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})
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);
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systemd.targets.acme-selfsigned-certificates = mkIf cfg.preliminarySelfsigned {};
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systemd.targets.acme-certificates = {};
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})
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];
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meta = {
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maintainers = lib.teams.acme.members;
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doc = ./acme.xml;
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};
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}
|