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1<chapter xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xmlns:xi="http://www.w3.org/2001/XInclude"
4 version="5.0"
5 xml:id="module-security-acme">
6
7<title>SSL/TLS Certificates with ACME</title>
8
9<para>NixOS supports automatic domain validation & certificate
10retrieval and renewal using the ACME protocol. This is currently only
11implemented by and for Let's Encrypt. The alternative ACME client
12<literal>simp_le</literal> is used under the hood.</para>
13
14<section><title>Prerequisites</title>
15
16<para>You need to have a running HTTP server for verification. The server must
17have a webroot defined that can serve
18<filename>.well-known/acme-challenge</filename>. This directory must be
19writeable by the user that will run the ACME client.</para>
20
21<para>For instance, this generic snippet could be used for Nginx:
22
23<programlisting>
24http {
25 server {
26 server_name _;
27 listen 80;
28 listen [::]:80;
29
30 location /.well-known/acme-challenge {
31 root /var/www/challenges;
32 }
33
34 location / {
35 return 301 https://$host$request_uri;
36 }
37 }
38}
39</programlisting>
40</para>
41
42</section>
43
44<section><title>Configuring</title>
45
46<para>To enable ACME certificate retrieval & renewal for a certificate for
47<literal>foo.example.com</literal>, add the following in your
48<filename>configuration.nix</filename>:
49
50<programlisting>
51security.acme.certs."foo.example.com" = {
52 webroot = "/var/www/challenges";
53 email = "foo@example.com";
54};
55</programlisting>
56</para>
57
58<para>The private key <filename>key.pem</filename> and certificate
59<filename>fullchain.pem</filename> will be put into
60<filename>/var/lib/acme/foo.example.com</filename>. The target directory can
61be configured with the option <literal>security.acme.directory</literal>.
62</para>
63
64<para>Refer to <xref linkend="ch-options" /> for all available configuration
65options for the <literal>security.acme</literal> module.</para>
66
67</section>
68
69<section><title>Using ACME certificates in Nginx</title>
70<para>NixOS supports fetching ACME certificates for you by setting
71<literal>enableACME = true;</literal> in a virtualHost config. We
72first create self-signed placeholder certificates in place of the
73real ACME certs. The placeholder certs are overwritten when the ACME
74certs arrive. For <literal>foo.example.com</literal> the config would
75look like.
76</para>
77
78<programlisting>
79services.nginx = {
80 enable = true;
81 virtualHosts = {
82 "foo.example.com" = {
83 forceSSL = true;
84 enableACME = true;
85 locations."/" = {
86 root = "/var/www";
87 };
88 };
89 };
90}
91</programlisting>
92
93<para>At the moment you still have to restart Nginx after the ACME
94certs arrive.</para>
95</section>
96</chapter>