1MEMCACHE_TABLE(5)             File Formats Manual            MEMCACHE_TABLE(5)
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NAME

6       memcache_table - Postfix memcache client configuration
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SYNOPSIS

9       postmap -q "string" memcache:/etc/postfix/filename
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11       postmap -q - memcache:/etc/postfix/filename <inputfile
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DESCRIPTION

14       The  Postfix  mail system uses optional tables for address rewriting or
15       mail routing. These tables are usually in dbm or db format.
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17       Alternatively, lookup tables can be specified  as  memcache  instances.
18       To  use memcache lookups, define a memcache source as a lookup table in
19       main.cf, for example:
20
21           virtual_alias_maps = memcache:/etc/postfix/memcache-aliases.cf
22
23       The file /etc/postfix/memcache-aliases.cf has the same  format  as  the
24       Postfix main.cf file, and specifies the parameters described below.
25
26       The  Postfix  memcache  client  supports the lookup, update, delete and
27       sequence (first/next) operations. The  sequence  operation  requires  a
28       backup database that supports the operation.
29

MEMCACHE MAIN PARAMETERS

31       memcache (default: inet:localhost:11211)
32              The  memcache  server  (note: singular) that Postfix will try to
33              connect to.  For a TCP server  specify  "inet:"  followed  by  a
34              hostname or address, ":", and a port name or number.  Specify an
35              IPv6 address inside "[]".   For  a  UNIX-domain  server  specify
36              "unix:" followed by the socket pathname. Examples:
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38                  memcache = inet:memcache.example.com:11211
39                  memcache = inet:127.0.0.1:11211
40                  memcache = inet:[fc00:8d00:189::3]:11211
41                  memcache = unix:/path/to/socket
42
43              NOTE:  to  access  a  UNIX-domain  socket  with  the proxymap(8)
44              server, the socket must be accessible by the unprivileged  post‐
45              fix user.
46
47       backup (default: undefined)
48              An optional Postfix database that provides persistent backup for
49              the memcache database. The Postfix memcache client  will  update
50              the  memcache  database whenever it looks up or changes informa‐
51              tion in the persistent database. Specify a Postfix  "type:table"
52              database. Examples:
53
54                  # Non-shared postscreen cache.
55                  backup = btree:/var/lib/postfix/postscreen_cache_map
56
57                  # Shared postscreen cache for processes on the same host.
58                  backup = proxy:btree:/var/lib/postfix/postscreen_cache_map
59
60              Access to remote proxymap servers is under development.
61
62              NOTE  1:  When  sharing  a persistent postscreen(8) or verify(8)
63              cache,     disable     automatic     cache     cleanup      (set
64              *_cache_cleanup_interval  =  0) except with one Postfix instance
65              that will be responsible for cache cleanup.
66
67              NOTE 2: When multiple tables share the same  memcache  database,
68              each  table  should  use  the  key_format feature (see below) to
69              prepend its own unique string to  the  lookup  key.   Otherwise,
70              automatic postscreen(8) or verify(8) cache cleanup may not work.
71
72              NOTE  3:  When  the  backup  database  is accessed with "proxy:"
73              lookups, the full backup database name (including  the  "proxy:"
74              prefix)   must   be   specified   in   the   proxymap   server's
75              proxy_read_maps  or  proxy_write_maps  setting   (depending   on
76              whether the access is read-only or read-write).
77
78       flags (default: 0)
79              Optional  flags  that  should  be  stored  along with a memcache
80              update. The flags are ignored when looking up information.
81
82       ttl (default: 3600)
83              The expiration time in seconds of memcache updates.
84
85              NOTE 1: When using a memcache table  as  postscreen(8)  or  ver‐
86              ify(8)   cache   without   persistent  backup,  specify  a  zero
87              *_cache_cleanup_interval value with all Postfix  instances  that
88              use  the  memcache,  and specify the largest postscreen(8) *_ttl
89              value or verify(8) *_expire_time value as the  memcache  table's
90              ttl value.
91
92              NOTE  2:  According  to memcache protocol documentation, a value
93              greater than 30 days (2592000 seconds) specifies  absolute  UNIX
94              time. Smaller values are relative to the time of the update.
95

MEMCACHE KEY PARAMETERS

97       key_format (default: %s)
98              Format  of  the lookup and update keys that the Postfix memcache
99              client sends to the memcache server.  By default, these are  the
100              same  as  the  lookup  and  update keys that the memcache client
101              receives from Postfix applications.
102
103              NOTE 1: The key_format feature is not used for  backup  database
104              requests.
105
106              NOTE  2:  When multiple tables share the same memcache database,
107              each table should prepend its own unique string  to  the  lookup
108              key.   Otherwise,  automatic  postscreen(8)  or  verify(8) cache
109              cleanup may not work.
110
111              Examples:
112
113                  key_format = aliases:%s
114                  key_format = verify:%s
115                  key_format = postscreen:%s
116
117              The key_format parameter supports the following '%' expansions:
118
119              %%     This is replaced by a literal '%' character.
120
121              %s     This is replaced by the memcache client input key.
122
123              %u     When the input key is an address of the form user@domain,
124                     %u  is  replaced  by  the  SQL  quoted  local part of the
125                     address.  Otherwise, %u is replaced by the entire  search
126                     string.   If the localpart is empty, a lookup is silently
127                     suppressed and returns no results (an update  is  skipped
128                     with a warning).
129
130              %d     When the input key is an address of the form user@domain,
131                     %d is replaced by the domain part of the address.  Other‐
132                     wise,  a  lookup  is  silently  suppressed and returns no
133                     results (an update is skipped with a warning).
134
135              %[SUD] The upper-case equivalents of the above expansions behave
136                     in   the   key_format   parameter  identically  to  their
137                     lower-case counter-parts.
138
139              %[1-9] The patterns %1, %2, ... %9 are replaced  by  the  corre‐
140                     sponding  most  significant  component of the input key's
141                     domain. If the input key is  user@mail.example.com,  then
142                     %1 is com, %2 is example and %3 is mail. If the input key
143                     is unqualified or does not have enough domain  components
144                     to  satisfy  all  the  specified  patterns,  a  lookup is
145                     silently suppressed and returns no results (an update  is
146                     skipped with a warning).
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148       domain (default: no domain list)
149              This  feature  can  significantly  reduce  database server load.
150              Specify a list of domain names, paths to files, or  "type:table"
151              databases.   When  specified,  only  fully qualified search keys
152              with a *non-empty* localpart and a matching domain are  eligible
153              for  lookup  or update: bare 'user' lookups, bare domain lookups
154              and "@domain" lookups are silently skipped (updates are  skipped
155              with a warning).  Example:
156
157                  domain = example.com, hash:/etc/postfix/searchdomains
158

MEMCACHE ERROR CONTROLS

160       data_size_limit (default: 10240)
161              The maximal memcache reply data length in bytes.
162
163       line_size_limit (default: 1024)
164              The maximal memcache reply line length in bytes.
165
166       max_try (default: 2)
167              The  number of times to try a memcache command before giving up.
168              The memcache client does not retry a command when  the  memcache
169              server accepts no connection.
170
171       retry_pause (default: 1)
172              The time in seconds before retrying a failed memcache command.
173
174       timeout (default: 2)
175              The  time limit for sending a memcache command and for receiving
176              a memcache reply.
177

BUGS

179       The Postfix memcache  client  cannot  be  used  for  security-sensitive
180       tables such as alias_maps (these may contain "|command and "/file/name"
181       destinations), or virtual_uid_maps, virtual_gid_maps and  virtual_mail‐
182       box_maps  (these specify UNIX process privileges or "/file/name" desti‐
183       nations).  In a typical deployment a memcache database is  writable  by
184       any  process  that  can talk to the memcache server; in contrast, secu‐
185       rity-sensitive tables must never be writable by the unprivileged  Post‐
186       fix user.
187
188       The Postfix memcache client requires additional configuration when used
189       as postscreen(8) or verify(8) cache.  For details see  the  backup  and
190       ttl  parameter  discussions  in  the  MEMCACHE  MAIN PARAMETERS section
191       above.
192

SEE ALSO

194       postmap(1), Postfix lookup table manager
195       postconf(5), configuration parameters
196

README FILES

198       Use "postconf readme_directory" or "postconf html_directory" to  locate
199       this information.
200       DATABASE_README, Postfix lookup table overview
201       MEMCACHE_README, Postfix memcache client guide
202

LICENSE

204       The Secure Mailer license must be distributed with this software.
205

HISTORY

207       Memcache support was introduced with Postfix version 2.9.
208

AUTHOR(S)

210       Wietse Venema
211       IBM T.J. Watson Research
212       P.O. Box 704
213       Yorktown Heights, NY 10598, USA
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215       Wietse Venema
216       Google, Inc.
217       111 8th Avenue
218       New York, NY 10011, USA
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