#!/bin/sh
#! -*-perl-*-
eval 'exec perl -x -S $0 ${1+"$@"}'
    if 0;

use strict;
use warnings;
use App::Acmeman;

App::Acmeman->new->run;

=head1 NAME

acmeman - manages ACME certificates

=head1 SYNOPSIS

B<acmeman>
[B<-Fadns>]
[B<-D> I<N>]
[B<-f> I<FILE>]
[B<--alt-names>]
[B<--config-file=>I<FILE>]
[B<--debug>]
[B<--dry-run>]
[B<--force>]
[B<--stage>]
[B<--time-delta=>I<N>]
[I<DOMAIN>...]

B<acmeman> B<--setup> | B<-S>
[B<-Fdn>]
[B<--config-file=>I<FILE>]
[B<--debug>]
[B<--dry-run>]
[B<--force>]

B<acmeman>
[B<-h>]
[B<--help>]
[B<--usage>]

=head1 DESCRIPTION

B<Acmeman> is a tool for automatic management of ACME (LetsEncrypt) SSL
certificates.

Most existing ACME tools take a list of domain names for which to issue
certificates from their command line or configuration file. B<Acmeman>
takes a completely different approach. It gathers domain names directly
from the configuration of the B<http> server that manages them. Thus,
a domain name obtains its certificate automatically, once the administrator
configures the http server to serve it via https.

This version of B<acmeman> is able to handle configuration files of
B<Apache> http server, and servers that are able to read the list of
domain names from disk files, such as B<HAProxy>.

For trivial configurations, B<acmeman> can be used without any additional
configuration.  For example, support for B<Apache> is enabled by default,
so all the administrator has to do is to run

    acmeman --setup

which will set up additional macro definitions for the apache configuration
file, then enable the B<mod_macro> module and to use the provided definitions
in httpd configuration.  This is discussed in detail in the section B<APACHE>
below.

In more complex configurations, B<acmeman> should be instructed what to
do using its configuration file.  This file, normally named
F</etc/acmeman.conf>, supplies the definitions of I<domain sources>,
i.e. configuration files from which to obtain domain names to form the
certificate CNs and other parameters.  At a pinch, the list of domain names
can be declared in it as well.  Several domain sources can be used
simultaneously. E.g. you can have B<acmeman> look for domain names in
B<Apache> and B<HAProxy> configurations and obtain an additional list of
domains from its own configuration, all in the same time.

In any case, B<acmeman> should be run as a periodic cron job, in order to
ensure that expiring certificates are updated in time.  The usual crontab
entry (for Vixie cron) is

    0 4 * * *   root    /usr/bin/acmeman

Exact interval configuration is entirely up to you.  For Dillon cron, omit
the user name field.

When started this way, B<acmeman> will scan the existing certificates and
select those of them which will expire within a predefined amount of time
(24h by default, configurable by the B<core.time-delta> statement). Then
it will scan the configured domain sources to see if any certificates are
added an alternative CN and if any new certificates should be issued. Having
created a list of the certificates, it will interact with the ACME server,
issuing the new ones and updating the ones that need prolongation or
modification.

=head1 QUICK START

The following is a short introduction to the B<acmeman> configuration. For
a detailed discussion, see the B<CONFIGURATION> section below. For detailed
discussion of particular domain sources, refer to the section B<SOURCES>.

The configuration file, B</etc/acmeman.conf>, consists of statements,
which have the form B<I<KW>=I<VAL>>, grouped into sections, declared
as B<[I<NAME>]> (square brackets are part of the syntax). Empty lines
and comments (introduced by a hash sign) are ignored.

There are three main use cases

=head2 APACHE

In most cases no special configuration file is needed.  The following
recipe describes each configuration step.  Refer to the section B<SOURCE>,
subsection B<apache> for a detailed discussion.

=over 4

=item 1. Initial configuration

Run

    acmeman --setup

It will detect the Apache layout, install an additional Apache configuration
file, F<httpd-letsencrypt.conf> and print the instructions on how to
enable it.  Follow them and enable the B<mod_macro> module.

=item 2. Apache domain setup: plain HTTP

To declare that a virtual host needs SSL certificate, add the following
line to the Apache B<VirtualHost> block serving plain HTTP for that host:

    Use LetsEncryptChallenge

This will instruct Apache B<httpd> to serve ACME challenges and B<acmeman>
to request a certificate for that virtual host.  The hostname declared with
the B<ServerName> statement will be used as the B<CN> for the certificate,
and any names declared via B<ServerAlias> statements will form the list of
alternative names.  For example:

    <VirtualHost *:80>
	ServerName example.org
	ServerAlias www.example.com
	Use LetsEncryptChallenge
	...
    </VirtualHost>

=item 3. Issue the certificate

This step is needed if there is no certificate for this domain yet. Reload
B<httpd> to fire up the new configuration and run B<acmeman> to issue the
certificate. If anything goes wrong, try adding one or more B<-d> options
to B<acmeman> to see what's going on. You can also use the B<-s> option
during initial debugging of the configuration. This option instructs B<acmeman>
to use the staging ACME server, instead of the production one. This eliminates
the risk of hitting the ACME request per IP limit.

=item 4. Apache domain setup: HTTPS

To use the created certificate, add another virtual server for that domain,
with the same B<ServerName> as above and with 443 as its port value. Add
the following statement to it:

    Use LetsEncryptSSL DOMAIN

where I<DOMAIN> must be the same as the B<ServerName> value.  For example,
the HTTPS virtual host corresponding to the above example will be:

    <VirtualHost *:443>
	ServerName example.org
	ServerAlias www.example.com
	Use LetsEncryptSSL example.org
	...
    </VirtualHost>

This can be further simplified by using the B<LetsEncryptServer> macro instead
of the B<ServerName> and B<LetsEncryptSSL> statements, as in:

    <VirtualHost *:443>
	Use LetsEncryptServer example.org
	ServerAlias www.example.com
	...
    </VirtualHost>

=back

=head2 HAPROXY

Use the B<file> source. This domain source reads the list of domain
names from a disk file. The first name in the list becomes the certificate
B<CN>, rest of names (if any) are used as alternative CNs. For a detailed
discussion of the B<file> source, refer to the section B<SOURCE>,
subsection B<file>.

=over 4

=item 1. Create a directory for storing domain name files

This directory will keep domain name files, named after the corresponding
HAProxy backends.  E.g.

    mkdir /etc/haproxy/hosts

=item 2. Configure acmeman

Example F</etc/acmeman.conf> file is:

    [core]
       source = file /etc/haproxy/hosts
       postrenew = /usr/sbin/service haproxy restart
    [files default]
       type = single
       certificate-file = /etc/ssl/acme/crt/$domain.pem

The B<core> section declares the source to use. The first argument to
the B<file> source is the name of the directory where the domain name lists
are stored. The B<postrenew> statement declares the command to be run
after all certificates have been renewed. In our case, this command restarts
B<haproxy>, forcing it to re-read the certificates.

The B<files> statement instructs the program to create, for each domain,
a single file containing the private key, certificate chain and the domain
certificate for that domain. The B<$domain> variable in the
B<certificate-file> declaration will be replaced by the first domain name
from the list (the B<CN>) for that certificate.

This configuration will keep a separate certificate for each backend in
B<haproxy> that supports https access.  If concerned about request rate
limit, you can instruct B<acmeman> to maintain a single certificate with
all domain names as X509v3 subject alternative names instead.  To do so,
use the B<--host> option in the source definition.  Its argument specifies
the domain name to use as the CN for the certificate.  E.g.:

    [core]
       source = file /etc/haproxy/hosts --host=www.example.com
       ...

=item 3. Configure haproxy

First, configure the plain HTTP frontend, which will be responsible for
serving ACME challenges and redirecting the rest of the requests to
HTTPS. The simplest definition is:

    frontend http-in
	mode http
	bind :::80 v4v6
	http-request redirect code 301 location https://%[hdr(host)]%[capture.req.uri] unless { path_beg /.well-known/acme-challenge }
	use_backend acme if { path_beg /.well-known/acme-challenge }

Actual backend configuration for the B<acme> backend is beyond the scope of
this manual. Use some simple and lightweight B<http> server capable of serving
static files, such as B<fileserv> (L<https://www.gnu.org.ua/projects/fileserv>),
for example.

Then, configure HTTPS section to use certificates from the certificate file
directory:

    frontend https-in
	mode http
	bind :::443 v4v6 ssl crt /etc/ssl/acme/crt
	# Direct each group of domain names to the corresponding
	# backend.
	use_backend d1 if { hdr(host) -f /etc/haproxy/hosts/d1 }
	use_backend d2 if { hdr(host) -f /etc/haproxy/hosts/d2 }
	...

Finally, define the backends.

=back

=head2 Direct configuration

Use direct configuration if none of the provided source types can
be used.  In this case, you define each domain which needs a
certificate in the F</etc/acmeman.conf> file.  First, instruct
B<acmeman> that no external source of domain names will be used:

    [core]
	source = null

Then, for each domain name use the B<domain> section, as shown in the
example below:

    [domain example.com]
	alt = www.example.com
	files = default

This section instructs B<acmeman> that a certificate is needed for
domain B<example.com>, using B<www.example.com> as its alternative name,
The B<files> statement identifies the name of a B<files> section containing
rules for creating certificate files for that domain. This section must be
defined elsewhere in the configuration file. For example:

    [files default]
	type = split
	certificate-file = /etc/ssl/acme/$domain/cert.pem
	key-file = /etc/ssl/acme/$domain/privkey.pem
	ca-file = /etc/ssl/acme/$domain/ca.pem
	argument = $domain

This definition tells B<acmeman> that it should store certificate, certificate
key, and certificate authority chain in three separate files. Names of these
files will be created by replacing the B<$domain> string in the corresponding
definition with the domain name from the B<domain> section.

Several B<[domain]> section can share the same B<[files]> definition, or
they can have their one, depending on your needs.

=head1 CONFIGURATION

Configuration file controls the operation of B<acmeman>. By default,
its name is B</etc/acmeman.conf>. If it is absent, B<acmeman> falls
back to the legacy operation mode, scanning Apache configuration files
for domains that use LetsEncrypt SSL certificates. See the B<APACHE>
section below for a detailed description.

The configuration file has a traditional line-oriented syntax. Comments
are introduced with a hash sign. Empty lines are ignored. Leading and
trailing whitespace is removed prior to parsing. Long statements can be
split over several physical lines by ending each line excepting the last
one with a backslash immediately followed by a newline character.

Configuration consists of settings grouped into sections.  Syntactically,
a I<setting> is

    KEYWORD = VALUE

where I<KEYWORD> stands for a symbolic name consisting of alphanumeric
characters, dashes and underscores, and I<VALUE> stands for any sequence
of characters.

A I<section> is identified by its name and optional arguments. It begins
with the following construct:

    [NAME]

or, if arguments are present:

    [NAME ARG1 ARG2 ...]

The square brackets are part of the syntax.

A section can contain one or more settings.

The statements in the configuration file form a directed graph. Often
in this document we will identify the statement by its I<path>, i.e. a
list of section name, its arguments, and the keyword, separated by dots. For
example, the path B<files.apache.type> corresponds to the following
configuration file fragment:

    [files apache]
       type = single


The following describes the available sections and keywords

=head2 B<[core]>

This section defines the behavior of the program as a whole.

=over 4

=item B<rootdir=>I<DIR>

Defines the root directory to use instead of the default </var/www/acme>.
Root directory is the directory under which the
F<.well-known/acme-challenge> subdirectory is located.

=item B<time-delta=>I<SECONDS>

Sets the time window before the actual expiration time, when the certificate
becomes eligible for renewal.  I<N> is time in seconds.  The default
value is 86400, which means that B<acmeman> will attempt to renew any
certificate that expires within 24 hours.

The command line option B<--time-delta> overrides this setting.

=item B<postrenew=>I<COMMAND>

Defines the command to be run at the end of the run if at least one
certificate has been updated. Normally this command reloads the httpd
server (or whatever server is using the certificates). If more than one
B<postrenew> statements are defined, they will be run in sequence, in the
same order as they appeared in the configuration file.

=item B<source=>I<NAME> [I<ARG>...]

Defines the source of domain names. The I<NAME> parameter identifies the
source, and additional arguments supply the initialization parameters.

The present version of B<acmeman> is shipped with three sources: B<null>,
B<apache>, and B<file>.

The B<null> module is an empty source. It takes no additional arguments.
Use this source if all domains are described in the configuration file
using one or more B<domain> sections.

The B<apache> source module is the default. It scans B<httpd> configuration
files as described in section B<apache>. One argument is allowed. If supplied,
it defines the apache configuration layout. Allowed values are: B<debian>,
B<slackware>, B<suse> and B<rh> (for Red Hat). Without arguments, the layout
will be autodetected.

The B<file> source reads domain names from one or more disk files. A
mandatory argument specifies the name of the directory where the files
are located. This mode is suitable for use with B<haproxy> pattern files.

Multiple B<source> statements can be defined. They will be processed
sequentially.

=item B<files=>I<NAME>

Identifies the B<[files]> section which describes how to create certificate
files for domains which lack explicit B<files> keyword. Default I<NAME> is
B<default>. See the description of the B<files> statement in B<domain>
section.

=item B<check-alt-names=>I<BOOL>

When set to B<true>, it instructs the program to compare the list of
alternative names of each certificate with the one gathered from the
Apache configuration, and reissue the certificate if the two lists
don't match.  This uses an ad-hoc logic, due to the deficiency of the
underlying X509 module, and therefore is not enabled by default.

Valid values for I<BOOL> are: B<1>, B<on>, B<true>, or B<yes>, for
true, and B<0>, B<off>, B<false>, or B<no> for false.

=item B<check-dns=>I<BOOL>

When set to B<true> (the default), the program will check whether each
host name has an A DNS record pointing back to one of the IP addresses
of the server. Hostnames which don't satisfy this condition will be ignored.
The IP of the server is determined by looking up the A record for its
hostname. This can be overridden using the B<my-ip> configuration statement.

=item B<key-size=>I<N>

Size of the RSA key to use, in bits. Default is 4096.

=item B<my-ip>=I<IP> [I<IP>...]

Declares IP address (or addresses) of this server. Use this keyword if
the server IP cannot be reliably determined by resolving its hostname.
Special I<IP> B<$hostip> stands for the IP retrieved by resolving the
hostname.

=back

=head2 B<[account]>

Configures where to store ACME account credentials: account key ID and
account private key.  Both values are stored in separate files on disk.
If the files do not exist B<acmeman> will initiate creation of a new
account and will save its credentials for further use.

=over 4

=item B<directory=>I<DIR>

Directory where to store credential files.  Defaults to
F</etc/ssl/acme>.

=item B<id=>I<FILE>

Name of the file with account key ID.  Unless I<FILE> begins with a
directory separator, it is taken relative to B<account.directory>.

Default: F</etc/ssl/acme/key.id>.

=item B<key=>I<FILE>

Name of the file with account key.  Unless I<FILE> begins with a
directory separator, it is taken relative to B<account.directory>.

Default: F</etc/ssl/acme/key.pem>.

=back

=head2 B<[domain I<CN>]>

Declares the domain for which a certificate should be maintained. I<CN> is
the canonical name for the domain. Alternative names can be specified using
the B<alt> setting within the section.

=over 4

=item B<files=>I<ID>

Identifies the B<[files]> section which describes how to create certificate
files for this domain. In the absence of this statement, the B<files>
statement from the B<[core]> section will be used.

=item B<alt=>I<NAME>

Defines alternative name for the certificate. Multiple B<alt> statements
are allowed.

=item B<key-size=>I<N>

Size of the RSA key to use, in bits. If not set, the B<core.key-size>
setting is used.

=item B<postrenew=>I<CMD>

Run I<CMD> after successful update. If not given, the B<core.postrenew>
commands will be run.

=back

=head2 B<[files I<ID>]>

The B<files> section instructs B<acmeman> how to create certificate files.
It is applied to particular domains by placing the B<files=I<ID>> statement
in the corresponding domain sections.

The I<FILENAME> arguments to the keywords below can contain references to
a I<meta-variable>, which will be replaced by the actual domain name when
handling this section for a particular domain. By default, this meta-variable
is B<$domain>.

=over 4

=item B<type=>B<single>|B<split>

Type of the certificate to create. When set to B<single>, a single
certificate file will be created. Its name is determined by the
B<certificate-file> statement. The file will contain the certificate,
certificate chain and the signature, in this order.

When set to B<split>, the certificate, certificate chain and the signature
will be saved to three distinct files, whose names are defined by
B<certificate-file>, B<ca-file>, and B<key-file>, correspondingly. If
B<ca-file> is not defined, only certificate and key files will be created.

The default is B<split>.

=item B<certificate-file=>I<FILENAME>

Defines the name of the certificate file for this domain. This statement
is mandatory.

=item B<key-file=>I<FILENAME>

Defines the name of the certificate key file. This statement must be present
if B<type> is set to B<split>.

=item B<ca-file=>I<FILENAME>

Defines the name of the certificate authority file. This statement may
be present if B<type> is set to B<split>.

=item B<argument=>I<STRING>

Defines the name of the meta-variable in I<FILENAME> arguments, which will
be replaced with the actual domain name. Default is B<$domain>.

=back

=head1 SOURCES

=head2 null

    [core]
	source = null

Declares empty source. This means that B<acmeman> will handle only domain
names explicitly declared in the configuration file using the B<domain>
setting.

=head2 apache

    [core]
	source = apache [--server-root=DIR] [LAYOUT]

This is the default source. It assumes Apache httpd, version 2.4 or later
(although only minor changes are necessary to make it work with version 2.2).
The optional I<LAYOUT> argument defines the layout of the apache configuration
files. Allowed layout values are: B<debian>, B<slackware>, B<suse> and
B<rh> (for Red Hat). If not supplied, the layout is determined automatically.

Use the B<--server-root> option to supply the name of the server root
directory, if for some reason the module is unable to determine it
automatically.

A special directory should be configured for receiving ACME challenges.

The package provides two Apache macros: for serving ACME challenges and
declaring SSL virtual hosts.

Upon startup the program scans Apache configuration for virtual hosts
that use ACME certificates, checks their expiration times, and renews those
of the certificates that are nearing their expiration times within a
predefined number of seconds (24 hours by default).  If any of the
certificates were updated during the run, B<acmeman> will restart the
B<httpd> server.

=head3 Setup

To set up the necessary infrastructure, run B<acmeman --setup>.  It will
create the configuration file B<httpd-letsencrypt.conf>, defining two
macros for SSL-enabled sites (B<mod_macro> is needed).  Finally, it will
create the directory B</var/www/acme>, which will be used for receiving
and serving ACME challenges.  If another directory is preferred, it can
be specified as an argument to B<acmeman --setup>.

The tool will try to determine the layout of the Apache configuration
files and place the created file accordingly, so that it will be included
into the main configuration file.  It will print the name of the created
file at the end of the run.  You are advised to ensure that the file is
included and that the module B<mod_macro> is loaded prior to it.  You
may also wish to revise B<httpd-letsencrypt.conf> and edit the paths to
SSL files configured there.  By default, the directory F</etc/acme/I<DOMAIN>>
will be created for each domain name needing SSL, and two files will be placed
there: F<cert.pem>, containing the leaf and intermediate certificates for that
domain, and F<privkey.pem>, containing the private key for that domain.

The program will refuse to overwrite existing files B<httpd-letsencrypt.conf>,
unless given the B<--force> (B<-F>) option.

=head3 Configuring SSL

To declare that a virtual host needs SSL certificate, add the following
line to the Apache B<VirtualHost> block serving plain HTTP for that host:

    Use LetsEncryptChallenge

This will instruct B<acmeman> to request a certificate for that virtual
host.  The hostname declared with the B<ServerName> statement will be used
as the B<CN> for the certificate, and any names declared via B<ServerAlias>
statements will form the list of alternative names (obviously, wildcards are
not allowed).

If such a certificate doesn't exist, it will be requested and created when
B<acmeman> is run.

To use the created certificate, create a new B<VirtualHost> block that
contains the following statement:

    Use LetsEncryptServer DOMAIN

where I<DOMAIN> is the name used in the B<ServerName> statement of the plain
HTTP configuration.  Copy the B<ServerAlias> statements (if any), and add the
rest of configuration statements.  Note, that you need not use the
B<ServerName> statement, as it will be included when the B<LetsEncryptServer>
macro is expanded.

Example:

    <VirtualHost *:80>
	ServerName example.org
	ServerAlias www.example.com
	Use LetsEncryptChallenge
	...
    </VirtualHost>

    <VirtualHost *:443>
	Use LetsEncryptServer example.org
	ServerAlias www.example.com
	...
    </VirtualHost>

Alternatively, you can use the B<LetsEncryptSSL> macro, which differs from
B<LetsEncryptServer> in that it configures only SSL settings, without the
B<ServerName> statement, which therefore must be included explicitly:

    <VirtualHost *:443>
	ServerName example.org
	ServerAlias www.example.com
	Use LetsEncryptSSL example.org
	...
    </VirtualHost>

LetsEncrypt limits the number of certificates requested for a single
registered domain per week (at the time of this writing - 20).  To avoid
hitting that limit, you may wish to use the same certificate for different
virtual hosts.  The special macro B<LetsEncryptReference> is provided for
that purpose.  Suppose, for example, that you wish to configure server
name B<git.example.org> to use the same certificate as B<example.org>
(configured in the example above).  You then declare the virtual host
for the plain HTTP as follows:

    <VirtualHost *:80>
	ServerName git.example.org
	Use LetsEncryptReference example.org
	...
    </VirtualHost>

The argument to the B<LetsEncryptReference> macro indicates the CN name of
the certificate to which the current server name (and aliases, if any) are
to be added as alternative names.  The corresponding virtual host for SSL
will use the B<LetsEncryptSSL> macro to configure the correct certificate:

    <VirtualHost *:80>
	ServerName git.example.org
	Use LetsEncryptSSL example.org
	...
    </VirtualHost>

=head2 file

    [core]
	source = file PATTERN [--ignore=RX] [--host=HOST]

Domain names will be read from files matching I<PATTERN>. The argument
can be a single file or directory name, or a valid globbing pattern.
If I<PATTERN> is a directory name, the module will read all files from
that directory, except those matching the following perl regexp:
C<^\.|~$|\.bak$|^#.*#$>. The default regexp can be overridden using the
B<--ignore> (B<-i>) option.

The input files must contain exactly one domain name per line. No empty
lines or comments are allowed. The first domain name will become the B<CN>
of the issued certificate. The rest of domain names will form alternative
names.

If the B<--host> (B<-h>) option is used, only one certificate will be
issued. The I<HOST> will be used as its B<CN>. All the domain names read
from the input files will form the list of its alternative names.

=head1 OPTIONS

=over 4

=item B<-D>, B<--time-delta=>I<N>

Sets the time window before the actual expiration time, when the certificate
becomes eligible for renewal.  I<N> is time in seconds.  The default
value is 86400, which means that B<acmeman> will attempt to renew any
certificate that expires within 24 hours.

This option overrides the B<core.time-delta> configuration setting.

=item B<-F>, B<--force>

Force renewal of certificates, no matter their expire date.  With B<--setup>,
force installing the B<httpd-letsencrypt.conf> file even if it already
exists.

=item B<-a>, B<--alt-names>

Compare the list of alternative names of each certificate with the one
gathered from the Apache configuration, and reissue the certificate
if the two lists don't match.  This uses an ad-hoc logic, due to the
deficiency of the underlying X509 module, and therefore is not enabled
by default.

This option overrides the B<core.check-alt-names> configuration setting.

=item B<-d>, B<--debug>

Increase debugging level.  Multiple options accumulate.  Three debugging
levels are implemented:

=over 8

=item B<-d>

List certificates being renewed.

=item B<-dd>

List files being created.  Show basic information about ACME transactions for
each certificate.

=item B<-ddd>

Verbosely report parsing of Apache configuration files.  Show detailed
debugging information about ACME transactions for each certificate.

=back

=item B<-f>, B<--config-file=>I<FILE>

Read configuration from I<FILE>, instead of the default F</etc/acmeman.conf>.

=item B<-n>, B<--dry-run>

Don't modify any files, just print what would have been done.
Implies B<--debug>.

=item B<-S>, B<--setup>

Set up the B<acmeman> infrastructure files.

=item B<-s>, B<--stage>

Use LetsEncrypt staging server.

=back

The following options are informational:

=over 4

=item B<-h>

Prints a short usage summary.

=item B<--help>

Prints detailed user manual.

=item B<--usage>

Outputs a terse reminder of the command line syntax along with a
list of available options.

=back

=head1 AUTHOR

Sergey Poznyakoff <gray@gnu.org>

=head1 LICENSE

GPLv3+: GNU GPL version 3 or later, see L<http://gnu.org/licenses/gpl.html>

This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
    
=cut