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Dovecot Dictionaries
====================

Dovecot's lib-dict can be used to access simple key-value databases. This is
used by for example <quota-dict> [Quota.Dict.txt], <passdb&userdb>
[AuthDatabase.Dict.txt], <last-login plugin> [Plugins.LastLogin.txt],
<METADATA> [ImapMetadata.txt], etc. The dictionaries can be accessed either
directly by the mail processes or they can be accessed via <dict proxy>
[Dict.txt] processes.

Currently supported dict backends are:

 * Flat files
 * FS (lib-fs wrapper)
 * Memcached (ASCII protocol)
 * Memcached (Binary protocol)
 * Redis
 * Proxy
 * SQL
 * LDAP (read only)

Flat Files
----------

---%<-------------------------------------------------------------------------
file:<path>
---%<-------------------------------------------------------------------------

The file will simply contain all the keys that are used. Not very efficient for
large databases, but good for small ones such as a single user's quota.

FS (v2.2.11+)
-------------

---%<-------------------------------------------------------------------------
fs:<driver>:<driver args>
---%<-------------------------------------------------------------------------

This is a wrapper for lib-fs, which most importantly has the "posix" backend.
So using:

---%<-------------------------------------------------------------------------
fs:posix:prefix=/var/lib/dovecot/dict
---%<-------------------------------------------------------------------------

Would create a separate file under /var/lib/dovecot/dict for each key.

Memcached (Binary Protocol) (v2.2.9+)
-------------------------------------

This driver uses the "new" Memcache binary protocol.

https://code.google.com/p/memcached/wiki/MemcacheBinaryProtocol

---%<-------------------------------------------------------------------------
memcached:param=value:param2=value2:...
---%<-------------------------------------------------------------------------

Supported parameters are:

 * host: Memcached server host (default: 127.0.0.1)
 * port: Memcached server port (default: 11211)
 * prefix: Prefix to add to all keys (default: empty)
 * timeout_msecs: Abort lookups after specified number of milliseconds
   (default: 30000)

Memcached (ASCII Protocol) (v2.2.9+)
------------------------------------

This driver uses the "legacy" Memcache ASCII protocol.

https://github.com/memcached/memcached/blob/master/doc/protocol.txt

---%<-------------------------------------------------------------------------
memcached_ascii:param=value:param2=value2:...
---%<-------------------------------------------------------------------------

Supported parameters are:

 * host: Memcached server host (default: 127.0.0.1)
 * port: Memcached server port (default: 11211)
 * prefix: Prefix to add to all keys (default: empty)
 * timeout_msecs: Abort lookups after specified number of milliseconds
   (default: 30000)

Redis (v2.2.9+)
---------------

---%<-------------------------------------------------------------------------
redis:param=value:param2=value2:...
---%<-------------------------------------------------------------------------

Supported parameters are:

 * host: Redis server host (default: 127.0.0.1)
 * port: Redis server port (default: 6379)
 * prefix: Prefix to add to all keys (default: empty)
 * db: Database number (default: 0)
 * expire_secs=<n>: Set expiration value to all the keys
 * timeout_msecs: Abort lookups after specified number of milliseconds
   (default: 30000)

Proxy
-----

---%<-------------------------------------------------------------------------
proxy:[<dict path>]:<destination dict>
---%<-------------------------------------------------------------------------

Proxying is used to perform all dictionary accessing via the dict processes.
(The dict processes exist only if dict proxying is used.) This is especially
useful with backends where their initialization is relatively expensive, such
as SQL. The dict processes will then perform also connection pooling.

If <dict path> is specified, it points to the socket where the dict server is
answering. The default is to use $base_dir/dict. Usually this is changed to
"dict-async" if the dict backend support asynchronous lookups (e.g. ldap,
pgsql, cassandra). The dict-async service allows more than one client, so this
configuration prevents creating unnecessarily many dict processes.

The <destination dict> contains the dict name in the dict { .. } settings. For
example:'proxy:dict-async:quota'

See <Dict.txt> for more information about the dict server.

SQL
---

---%<-------------------------------------------------------------------------
<sql driver>:<path to dict-sql config>
---%<-------------------------------------------------------------------------

The <sql driver> contains the SQL driver name, such as "mysql", "pgsql",
"sqlite" or "cassandra".

The dict-sql config file consists of SQL server configuration and mapping of
keys to SQL tables/fields.

SQL Connect String
------------------

---%<-------------------------------------------------------------------------
connect = host=localhost dbname=mails user=sqluser password=sqlpass
---%<-------------------------------------------------------------------------

The connect setting is exactly the same as used for <SQL passdb/userdb>
[AuthDatabase.SQL.txt]. See 'example-config/dovecot-sql.conf.ext' for detailed
information.

SQL Mapping
-----------

SQL mapping is done with a dict key pattern and fields. When a dict lookup or
update is done, Dovecot goes through all the maps and uses the first one whose
pattern matches the dict key.

For example when using dict for a per-user quota value the map looks like:

---%<-------------------------------------------------------------------------
map {
  pattern = priv/quota/storage
  table = quota
  username_field = username
  value_field = quota_bytes
}
---%<-------------------------------------------------------------------------

This means that:

 * The dict key must match exactly "priv/quota/storage". The dict keys are
   hardcoded in the Dovecot code, so depending on what functionality you're
   configuring you need to know the available dict keys used it.
 * This is a private dict key ("priv/" prefix), which means that there must be
   a username_field. The username_field is assumed to be (at least part of) the
   primary key. In this example we don't have any other primary keys.
 * With MySQL the above map translates to SQL queries:
    * 'SELECT quota_bytes FROM quota WHERE username = '$username_field''
    * 'INSERT INTO quota (username, quota_bytes) VALUES ('$username_field',
      '$value') ON DUPLICATE KEY UPDATE quota_bytes='$value''

You can also access multiple SQL fields. For example acl_shared_dict can
contain:

---%<-------------------------------------------------------------------------
map {
  pattern = shared/shared-boxes/user/$to/$from
  table = user_shares
  value_field = dummy

  fields {
    from_user = $from
    to_user = $to
  }
}
---%<-------------------------------------------------------------------------

 * The acl_shared_dict always uses "1" as the value, so here the value_field is
   called "dummy".
 * The SQL from_user and to_user fields are the interesting ones. Typically the
   extra fields would be part of the primary key.
 * With MySQL the above map translates to SQL queries:
    * 'SELECT dummy FROM user_shares WHERE from_user = '$from' AND to_user =
      '$to''
    * 'INSERT INTO user_shares (from_user, to_user, dummy) VALUES ('$from',
      '$to', '$value') ON DUPLICATE KEY UPDATE dummy='$value''

LDAP (v2.2.24+)
---------------

LDAP support is very similar to SQL support, but there is no write support.

Configuration
-------------

---%<-------------------------------------------------------------------------
dict {
  somedict = ldap:/path/to/dovecot-ldap-dict.conf.ext
}
---%<-------------------------------------------------------------------------

Then in ext file put

---%<-------------------------------------------------------------------------
uri = ldap://hostname
bind_dn = optional bind dn
password = optional password
timeout = optional timeout
debug = 0 or 1 (optional, as well)
tls = yes|try|no (default is try)
---%<-------------------------------------------------------------------------

 * uri - LDAP connection URI as expected by OpenLDAP.
 * bind_dn - DN or upn to use for binding
 * password - password to use, only SIMPLE auth is supported at the moment
 * timeout - How long to wait for reply, default is 30 seconds
 * debug - 0 off, 1 on, will produce metric ton of output
 * tls - yes = require either ldaps or successful start TLS, try = send start
   TLS if necessary, no = do not send start TLS

To map some key to a search do

---%<-------------------------------------------------------------------------
map {
  pattern = priv/test/mail
  filter = (mail=*)  # the () is required
  base_dn = ou=container,dc=domain
  username_attribute = uid # default is cn
  value_attribute = mail
}
---%<-------------------------------------------------------------------------

To do some more complex search

---%<-------------------------------------------------------------------------
map {
  pattern = priv/test/mail/$location
  filter = (&(mail=*)(location=%{location}) # the () is required
  base_dn = ou=container,dc=domain
  username_attribute = uid # default is cn
  value_attribute = mail

  fields {
    location=$location
  }
}
---%<-------------------------------------------------------------------------

(This file was created from the wiki on 2019-06-19 12:42)