nixos/acme: replace simp-le with lego client

Lego allows users to use the DNS-01 challenge to validate their
certificates. It is mostly backwards compatible, with a few
caveats.

 - extraDomains can no longer have different webroots to the
   main webroot for the cert.
 - An email address is now mandatory for account creation

The following other changes were required:
 - Deprecate security.acme.certs.<name>.plugins, as this was
   specific to simp-le
 - Rename security.acme.validMin to validMinDays, to avoid
   confusion and errors. Lego requires the TTL to be specified in
   days
 - Add options to cover DNS challenge (dnsProvider,
   credentialsFile, dnsPropagationCheck)
 - A shared state directory is now used (/var/lib/acme/.lego)
   to avoid account creation rate limits and share credentials
   between certs
This commit is contained in:
Lucas Savva 2020-01-12 21:05:57 +00:00
parent 832d1f4a57
commit 1e3607d331
2 changed files with 103 additions and 40 deletions

View file

@ -1,7 +1,5 @@
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.security.acme;
@ -76,20 +74,6 @@ let
'';
};
plugins = mkOption {
type = types.listOf (types.enum [
"cert.der" "cert.pem" "chain.pem" "external.sh"
"fullchain.pem" "full.pem" "key.der" "key.pem" "account_key.json" "account_reg.json"
]);
default = [ "fullchain.pem" "full.pem" "key.pem" "account_key.json" "account_reg.json" ];
description = ''
Plugins to enable. With default settings simp_le will
store public certificate bundle in <filename>fullchain.pem</filename>,
private key in <filename>key.pem</filename> and those two previous
files combined in <filename>full.pem</filename> in its state directory.
'';
};
directory = mkOption {
type = types.str;
readOnly = true;
@ -111,6 +95,31 @@ let
own server roots if needed.
'';
};
dnsProvider = mkOption {
type = types.nullOr types.str;
example = "route53";
default = null;
description = "DNS Challenge provider";
};
credentialsFile = mkOption {
type = types.str;
description = ''
File containing DNS provider credentials passed as environment variables.
See https://go-acme.github.io/lego/dns/ for more information.
'';
example = "/var/src/secrets/example.org-route53-api-token";
};
dnsPropagationCheck = mkOption {
type = types.bool;
default = true;
description = ''
Toggles LEGo DNS propagation check, which is used alongside DNS-01
challenge to ensure the DNS entries required are available
'';
};
};
};
@ -130,14 +139,21 @@ in
(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.")
(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")
(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")
(mkChangedOptionModule [ "security" "acme" "validMin"] [ "security" "acme" "validMinDays"] (config: config.security.acme.validMin / (24 * 3600)))
];
options = {
security.acme = {
validMin = mkOption {
validMinDays = mkOption {
type = types.int;
default = 30 * 24 * 3600;
description = "Minimum remaining validity before renewal in seconds.";
default = 30;
description = "Minimum remaining validity before renewal in days.";
};
email = mkOption {
type = types.nullOr types.str;
default = null;
description = "Contact email address for the CA to be able to reach you.";
};
renewInterval = mkOption {
@ -173,6 +189,15 @@ in
'';
};
acceptTerms = mkOption {
type = types.bool;
default = true;
description = ''
Accept the current Let's Encrypt terms of service.
See https://letsencrypt.org/repository/
'';
};
certs = mkOption {
default = { };
type = with types; attrsOf (submodule certOpts);
@ -204,27 +229,47 @@ in
config = mkMerge [
(mkIf (cfg.certs != { }) {
assertions = let
certs = (mapAttrsToList (k: v: v) cfg.certs);
in [
{
assertion = all (certOpts: certOpts.dnsProvider == null || certOpts.webroot == null) certs;
message = ''
Options `security.acme.certs.<name>.dnsProvider` and
`security.acme.certs.<name>.webroot` are mutually exclusive.
'';
}
{
assertion = cfg.email != null || all (certOpts: certOpts.email != null) certs;
message = ''
You must define `security.acme.certs.<name>.email` or
`security.acme.email` to register with the CA.
'';
}
];
systemd.services = let
services = concatLists servicesLists;
servicesLists = mapAttrsToList certToServices cfg.certs;
certToServices = cert: data:
let
# StateDirectory must be relative, and will be created under /var/lib by systemd
lpath = "acme/${cert}";
apath = "/var/lib/${lpath}";
spath = "/var/lib/acme/.lego";
rights = if data.allowKeysForGroup then "750" else "700";
cmdline = [ "-v" "-d" data.domain "--default_root" data.webroot "--valid_min" cfg.validMin ]
++ optionals (data.email != null) [ "--email" data.email ]
++ concatMap (p: [ "-f" p ]) data.plugins
++ concatLists (mapAttrsToList (name: root: [ "-d" (if root == null then name else "${name}:${root}")]) data.extraDomains)
globalOpts = [ "-d" data.domain "--email" data.email "--path" "." ]
++ optionals (cfg.acceptTerms) [ "--accept-tos" ]
++ optionals (data.dnsProvider != null && !cfg.dnsPropagationCheck) [ "--dns.disable-cp" ]
++ concatLists (mapAttrsToList (name: root: [ "-d" name ]) data.extraDomains)
++ (if data.dnsProvider != null then [ "--dns" data.dnsProvider ] else [ "--http" "--http.webroot" data.webroot ])
++ optionals (cfg.server != null || data.server != null) ["--server" (if data.server == null then cfg.server else data.server)];
runOpts = escapeShellArgs (globalOpts ++ [ "run" ]);
renewOpts = escapeShellArgs (globalOpts ++ [ "renew" "--days" (toString cfg.validMinDays) ]);
acmeService = {
description = "Renew ACME Certificate for ${cert}";
after = [ "network.target" "network-online.target" ];
wants = [ "network-online.target" ];
# simp_le uses requests, which uses certifi under the hood,
# which doesn't respect the system trust store.
# At least in the acme test, we provision a fake CA, impersonating the LE endpoint.
# REQUESTS_CA_BUNDLE is a way to teach python requests to use something else
environment.REQUESTS_CA_BUNDLE = "/etc/ssl/certs/ca-certificates.crt";
serviceConfig = {
Type = "oneshot";
# With RemainAfterExit the service is considered active even
@ -233,18 +278,36 @@ in
# the permissions of the StateDirectory get adjusted
# according to the specified group
RemainAfterExit = true;
SuccessExitStatus = [ "0" "1" ];
User = data.user;
Group = data.group;
PrivateTmp = true;
StateDirectory = lpath;
StateDirectory = "acme/.lego ${lpath}";
StateDirectoryMode = rights;
WorkingDirectory = "/var/lib/${lpath}";
ExecStart = "${pkgs.simp_le}/bin/simp_le ${escapeShellArgs cmdline}";
WorkingDirectory = spath;
# Only try loading the credentialsFile if the dns challenge is enabled
EnvironmentFile = if data.dnsProvider != null then data.credentialsFile else null;
ExecStart = pkgs.writeScript "acme-start" ''
#!${pkgs.runtimeShell} -e
${pkgs.lego}/bin/lego ${renewOpts} || ${pkgs.lego}/bin/lego ${runOpts}
'';
ExecStartPost =
let
script = pkgs.writeScript "acme-post-start" ''
#!${pkgs.runtimeShell} -e
cd ${apath}
# Test that existing cert is older than new cert
KEY=${spath}/certificates/*${data.domain}.key
if [ -e $KEY -a $KEY -nt key.pem ]; then
cp -p ${spath}/certificates/*${data.domain}.key key.pem
cp -p ${spath}/certificates/*${data.domain}.crt cert.pem
cp -p ${spath}/certificates/*${data.domain}.issuer.crt chain.pem
cat cert.pem chain.pem > fullchain.pem
cat key.pem cert.pem chain.pem > full.pem
chmod ${rights} *.pem
chown '${data.user}:${data.group}' *.pem
fi
${data.postRun}
'';
in
@ -276,17 +339,17 @@ in
-out $workdir/server.crt
# Copy key to destination
cp $workdir/server.key /var/lib/${lpath}/key.pem
cp $workdir/server.key ${apath}/key.pem
# Create fullchain.pem (same format as "simp_le ... -f fullchain.pem" creates)
cat $workdir/{server.crt,ca.crt} > "/var/lib/${lpath}/fullchain.pem"
cat $workdir/{server.crt,ca.crt} > "${apath}/fullchain.pem"
# Create full.pem for e.g. lighttpd
cat $workdir/{server.key,server.crt,ca.crt} > "/var/lib/${lpath}/full.pem"
cat $workdir/{server.key,server.crt,ca.crt} > "${apath}/full.pem"
# Give key acme permissions
chown '${data.user}:${data.group}' "/var/lib/${lpath}/"{key,fullchain,full}.pem
chmod ${rights} "/var/lib/${lpath}/"{key,fullchain,full}.pem
chown '${data.user}:${data.group}' "${apath}/"{key,fullchain,full}.pem
chmod ${rights} "${apath}/"{key,fullchain,full}.pem
'';
serviceConfig = {
Type = "oneshot";
@ -297,7 +360,7 @@ in
};
unitConfig = {
# Do not create self-signed key when key already exists
ConditionPathExists = "!/var/lib/${lpath}/key.pem";
ConditionPathExists = "!${apath}/key.pem";
};
};
in (
@ -334,7 +397,7 @@ in
];
meta = {
maintainers = with lib.maintainers; [ abbradar fpletz globin ];
maintainers = with lib.maintainers; [ abbradar fpletz globin m1cr0man ];
doc = ./acme.xml;
};
}

View file

@ -7,7 +7,7 @@
<para>
NixOS supports automatic domain validation &amp; certificate retrieval and
renewal using the ACME protocol. This is currently only implemented by and
for Let's Encrypt. The alternative ACME client <literal>simp_le</literal> is
for Let's Encrypt. The alternative ACME client <literal>LEGo</literal> is
used under the hood.
</para>
<section xml:id="module-security-acme-prerequisites">