memcache_table(5) - man - phpman

MEMCACHE_TABLE(5)                        File Formats Manual                       MEMCACHE_TABLE(5)



NAME
       memcache_table - Postfix memcache client configuration

SYNOPSIS
       postmap -q "string" memcache:/etc/postfix/filename

       postmap -q - memcache:/etc/postfix/filename <inputfile

DESCRIPTION
       The Postfix mail system uses optional tables for address rewriting or mail routing. These ta‐
       bles are usually in dbm or db format.

       Alternatively, lookup tables can  be  specified  as  memcache  instances.   To  use  memcache
       lookups, define a memcache source as a lookup table in main.cf, for example:

           virtual_alias_maps = memcache:/etc/postfix/memcache-aliases.cf

       The  file  /etc/postfix/memcache-aliases.cf  has the same format as the Postfix main.cf file,
       and specifies the parameters described below.

       The Postfix memcache client supports the lookup, update, delete and sequence (first/next) op‐
       erations. The sequence operation requires a backup database that supports the operation.

MEMCACHE MAIN PARAMETERS
       memcache (default: inet:localhost:11211)
              The  memcache  server (note: singular) that Postfix will try to connect to.  For a TCP
              server specify "inet:" followed by a hostname or address, ":", and a port name or num‐
              ber.   Specify  an IPv6 address inside "[]".  For a UNIX-domain server specify "unix:"
              followed by the socket pathname. Examples:

                  memcache = inet:memcache.example.com:11211
                  memcache = inet:127.0.0.1:11211
                  memcache = inet:[fc00:8d00:189::3]:11211
                  memcache = unix:/path/to/socket

              NOTE: to access a UNIX-domain socket with the proxymap(8) server, the socket  must  be
              accessible by the unprivileged postfix user.

       backup (default: undefined)
              An  optional  Postfix  database that provides persistent backup for the memcache data‐
              base. The Postfix memcache client will update the memcache database whenever it  looks
              up  or  changes information in the persistent database. Specify a Postfix "type:table"
              database. Examples:

                  # Non-shared postscreen cache.
                  backup = btree:/var/lib/postfix/postscreen_cache_map

                  # Shared postscreen cache for processes on the same host.
                  backup = proxy:btree:/var/lib/postfix/postscreen_cache_map

              Access to remote proxymap servers is under development.

              NOTE 1: When sharing a persistent postscreen(8) or verify(8) cache, disable  automatic
              cache cleanup (set *_cache_cleanup_interval = 0) except with one Postfix instance that
              will be responsible for cache cleanup.

              NOTE 2: When multiple tables share the same memcache database, each table  should  use
              the key_format feature (see below) to prepend its own unique string to the lookup key.
              Otherwise, automatic postscreen(8) or verify(8) cache cleanup may not work.

              NOTE 3: When the backup database is accessed with "proxy:" lookups,  the  full  backup
              database  name  (including  the  "proxy:"  prefix)  must  be specified in the proxymap
              server's proxy_read_maps or proxy_write_maps setting (depending on whether the  access
              is read-only or read-write).

       flags (default: 0)
              Optional  flags  that should be stored along with a memcache update. The flags are ig‐
              nored when looking up information.

       ttl (default: 3600)
              The expiration time in seconds of memcache updates.

              NOTE 1: When using a memcache table as postscreen(8) or verify(8) cache  without  per‐
              sistent  backup,  specify  a  zero *_cache_cleanup_interval value with all Postfix in‐
              stances that use the memcache, and specify the largest postscreen(8)  *_ttl  value  or
              verify(8) *_expire_time value as the memcache table's ttl value.

              NOTE  2:  According  to  memcache protocol documentation, a value greater than 30 days
              (2592000 seconds) specifies absolute UNIX time. Smaller values  are  relative  to  the
              time of the update.

MEMCACHE KEY PARAMETERS
       key_format (default: %s)
              Format  of  the  lookup  and update keys that the Postfix memcache client sends to the
              memcache server.  By default, these are the same as the lookup and  update  keys  that
              the memcache client receives from Postfix applications.

              NOTE 1: The key_format feature is not used for backup database requests.

              NOTE  2:  When  multiple  tables  share  the same memcache database, each table should
              prepend its own unique string to the lookup key.  Otherwise,  automatic  postscreen(8)
              or verify(8) cache cleanup may not work.

              Examples:

                  key_format = aliases:%s
                  key_format = verify:%s
                  key_format = postscreen:%s

              The key_format parameter supports the following '%' expansions:

              %%     This is replaced by a literal '%' character.

              %s     This is replaced by the memcache client input key.

              %u     When the input key is an address of the form user@domain, %u is replaced by the
                     SQL quoted local part of the address.  Otherwise, %u is replaced by the  entire
                     search  string.  If the localpart is empty, a lookup is silently suppressed and
                     returns no results (an update is skipped with a warning).

              %d     When the input key is an address of the form user@domain, %d is replaced by the
                     domain part of the address.  Otherwise, a lookup is silently suppressed and re‐
                     turns no results (an update is skipped with a warning).

              %[SUD] The upper-case equivalents of the above expansions behave in the key_format pa‐
                     rameter identically to their lower-case counter-parts.

              %[1-9] The  patterns %1, %2, ... %9 are replaced by the corresponding most significant
                     component of the input key's domain. If the input key is user AT mail.com,
                     then  %1  is com, %2 is example and %3 is mail. If the input key is unqualified
                     or does not have enough domain components to satisfy  all  the  specified  pat‐
                     terns,  a  lookup  is  silently suppressed and returns no results (an update is
                     skipped with a warning).

       domain (default: no domain list)
              This feature can significantly reduce database server load.  Specify a list of  domain
              names,  paths  to files, or "type:table" databases.  When specified, only fully quali‐
              fied search keys with a *non-empty* localpart and a matching domain are  eligible  for
              lookup  or  update: bare 'user' lookups, bare domain lookups and "@domain" lookups are
              silently skipped (updates are skipped with a warning).  Example:

                  domain = example.com, hash:/etc/postfix/searchdomains

MEMCACHE ERROR CONTROLS
       data_size_limit (default: 10240)
              The maximal memcache reply data length in bytes.

       line_size_limit (default: 1024)
              The maximal memcache reply line length in bytes.

       max_try (default: 2)
              The number of times to try a memcache command before giving up.  The  memcache  client
              does not retry a command when the memcache server accepts no connection.

       retry_pause (default: 1)
              The time in seconds before retrying a failed memcache command.

       timeout (default: 2)
              The time limit for sending a memcache command and for receiving a memcache reply.

BUGS
       The  Postfix  memcache client cannot be used for security-sensitive tables such as alias_maps
       (these may contain  "|command  and  "/file/name"  destinations),  or  virtual_uid_maps,  vir‐‐
       tual_gid_maps and virtual_mailbox_maps (these specify UNIX process privileges or "/file/name"
       destinations).  In a typical deployment a memcache database is writable by any  process  that
       can  talk  to  the  memcache  server;  in  contrast,  security-sensitive tables must never be
       writable by the unprivileged Postfix user.

       The Postfix memcache client requires additional configuration when used as  postscreen(8)  or
       verify(8)  cache.   For  details see the backup and ttl parameter discussions in the MEMCACHE
       MAIN PARAMETERS section above.

SEE ALSO
       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters

README FILES
       Use "postconf readme_directory" or "postconf html_directory" to locate this information.
       DATABASE_README, Postfix lookup table overview
       MEMCACHE_README, Postfix memcache client guide

LICENSE
       The Secure Mailer license must be distributed with this software.

HISTORY
       Memcache support was introduced with Postfix version 2.9.

AUTHOR(S)
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA



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