nixpkgs/nixos/modules/security/acme.xml

<chapter xmlns="http://docbook.org/ns/docbook"
         xmlns:xlink="http://www.w3.org/1999/xlink"
         xmlns:xi="http://www.w3.org/2001/XInclude"
         version="5.0"
         xml:id="module-security-acme">
 <title>SSL/TLS Certificates with ACME</title>
 <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
  used under the hood.
 </para>
 <section xml:id="module-security-acme-prerequisites">
  <title>Prerequisites</title>

  <para>
   You need to have a running HTTP server for verification. The server must
   have a webroot defined that can serve
   <filename>.well-known/acme-challenge</filename>. This directory must be
   writeable by the user that will run the ACME client.
  </para>

  <para>
   For instance, this generic snippet could be used for Nginx:
<programlisting>
http {
  server {
    server_name _;
    listen 80;
    listen [::]:80;

    location /.well-known/acme-challenge {
      root /var/www/challenges;
    }

    location / {
      return 301 https://$host$request_uri;
    }
  }
}
</programlisting>
  </para>
 </section>
 <section xml:id="module-security-acme-configuring">
  <title>Configuring</title>

  <para>
   To enable ACME certificate retrieval &amp; renewal for a certificate for
   <literal>foo.example.com</literal>, add the following in your
   <filename>configuration.nix</filename>:
<programlisting>
<xref linkend="opt-security.acme.certs"/>."foo.example.com" = {
  <link linkend="opt-security.acme.certs._name_.webroot">webroot</link> = "/var/www/challenges";
  <link linkend="opt-security.acme.certs._name_.email">email</link> = "foo@example.com";
};
</programlisting>
  </para>

  <para>
   The private key <filename>key.pem</filename> and certificate
   <filename>fullchain.pem</filename> will be put into
   <filename>/var/lib/acme/foo.example.com</filename>. The target directory can
   be configured with the option <xref linkend="opt-security.acme.directory"/>.
  </para>

  <para>
   Refer to <xref linkend="ch-options" /> for all available configuration
   options for the <link linkend="opt-security.acme.certs">security.acme</link>
   module.
  </para>
 </section>
 <section xml:id="module-security-acme-nginx">
  <title>Using ACME certificates in Nginx</title>

  <para>
   NixOS supports fetching ACME certificates for you by setting
   <literal><link linkend="opt-services.nginx.virtualHosts._name_.enableACME">enableACME</link>
   = true;</literal> in a virtualHost config. We first create self-signed
   placeholder certificates in place of the real ACME certs. The placeholder
   certs are overwritten when the ACME certs arrive. For
   <literal>foo.example.com</literal> the config would look like.
  </para>

<programlisting>
services.nginx = {
  <link linkend="opt-services.nginx.enable">enable = true;</link>
  <link linkend="opt-services.nginx.virtualHosts">virtualHosts</link> = {
    "foo.example.com" = {
      <link linkend="opt-services.nginx.virtualHosts._name_.forceSSL">forceSSL</link> = true;
      <link linkend="opt-services.nginx.virtualHosts._name_.enableACME">enableACME</link> = true;
      locations."/" = {
        <link linkend="opt-services.nginx.virtualHosts._name_.locations._name_.root">root</link> = "/var/www";
      };
    };
  };
}
</programlisting>
 </section>
</chapter>