Added opendkim integration doc.

doc/installation.rst

@@ -51,6 +51,7 @@ specific part, here are the steps you must follow:
    manual_installation/webserver
    manual_installation/dovecot
    manual_installation/postfix
+   manual_installation/opendkim
 
 Extensions
 ----------

doc/manual_installation/opendkim.rst

@@ -0,0 +1,75 @@
+########
+OpenDKIM
+########
+
+Modoboa can generate `DKIM
+<https://en.wikipedia.org/wiki/DomainKeys_Identified_Mail>`_ keys for
+the hosted domains but it won't sign or check messages. To do that,
+you need a dedicated software like `OpenDKIM <http://opendkim.org/>`_.
+
+Database
+========
+
+Since keys related information is stored in Modoboa's database, you
+need to tell OpenDKIM how it can access it.
+
+First, make sure to install the required additional packages on your
+system (``libopendbx1`` on debian based distributions or ``opendbx``
+on CentOS, the complete name depends on your database engine).
+
+Then, insert the following SQL view into Modoboa's database:
+
+PostgreSQL
+----------
+
+::
+
+   CREATE OR REPLACE VIEW dkim AS (
+     SELECT id, name as domain_name, dkim_private_key_path AS private_key_path,
+          dkim_key_selector AS selector
+     FROM admin_domain WHERE enable_dkim
+   );
+
+ MySQL/MariaDB
+ -------------
+
+::
+   
+   CREATE OR REPLACE VIEW dkim AS (
+     SELECT id, name as domain_name, dkim_private_key_path AS private_key_path,
+          dkim_key_selector AS selector
+     FROM admin_domain WHERE enable_dkim=1
+   );
+
+Configuration
+=============
+
+You should find OpenDKIM's configuration file at :file:`/etc/opendkim.conf`.
+
+Add the following content to it::
+
+  KeyTable		dsn:<driver>://<user>:<password>@<db host>/<db name>/table=dkim?keycol=id?datacol=domain_name,selector,private_key_path
+  SigningTable		dsn:<driver>://<user>:<password>@<db host>/<db name>/table=dkim?keycol=domain_name?datacol=id
+  Socket                inet:12345@localhost
+
+Replace values between ``<>`` by yours. Accepted values for ``driver``
+are ``pgsql`` or ``mysql``.
+
+If you run a debian based system, make sure to adjust the following
+setting in the :file:`/etc/default/opendkim` file::
+
+  SOCKET=inet:12345@localhost
+
+Eventually, reload OpenDKIM.
+
+Postfix integration
+===================
+
+Add the following lines to the :file:`/etc/postfix/main.cf` file::
+
+  smtpd_milters = inet:127.0.0.1:12345
+  non_smtpd_milters = inet:127.0.0.1:12345
+  milter_default_action = accept
+  milter_content_timeout = 30s
+
+and reload postfix.