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<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
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<title> Postfix manual - postfix-wrapper(5) </title>
</head> <body> <pre>
POSTFIX-WRAPPER(5) POSTFIX-WRAPPER(5)
<b>NAME</b>
postfix-wrapper - Postfix multi-instance API
<b>DESCRIPTION</b>
Support for managing multiple Postfix instances is available as of ver-
sion 2.6. Instances share executable files and documentation, but have
their own directories for configuration, queue and data files.
This document describes how the familiar "postfix start" etc. user
interface can be used to manage one or multiple Postfix instances, and
gives details of an API to coordinate activities between the <a href="postfix.1.html">postfix(1)</a>
command and a multi-instance manager program.
With multi-instance support, the default Postfix instance is always
required. This instance is identified by the <a href="postconf.5.html#config_directory">config_directory</a> parame-
ter's default value.
<b>GENERAL OPERATION</b>
Multi-instance support is backwards compatible: when you run only one
Postfix instance, commands such as "postfix start" will not change
behavior at all.
Even with multiple Postfix instances, you can keep using the same post-
fix commands in boot scripts, upgrade procedures, and other places. The
commands do more work, but humans are not forced to learn new tricks.
For example, to start all Postfix instances, use:
# postfix start
Other <a href="postfix.1.html">postfix(1)</a> commands also work as expected. For example, to find
out what Postfix instances exist in a multi-instance configuration,
use:
# postfix status
This enumerates the status of all Postfix instances within a
multi-instance configuration.
<b>MANAGING AN INDIVIDUAL POSTFIX INSTANCE</b>
To manage a specific Postfix instance, specify its configuration direc-
tory on the <a href="postfix.1.html">postfix(1)</a> command line:
# postfix -c <i>/path/to/config</i><b>_</b><i>directory command</i>
Alternatively, the <a href="postfix.1.html">postfix(1)</a> command accepts the instance's configura-
tion directory via the MAIL_CONFIG environment variable (the -c com-
mand-line option has higher precedence).
Otherwise, the <a href="postfix.1.html">postfix(1)</a> command will operate on all Postfix
instances.
<b>ENABLING POSTFIX(1) MULTI-INSTANCE MODE</b>
By default, the <a href="postfix.1.html">postfix(1)</a> command operates in single-instance mode. In
this mode the command invokes the postfix-script file directly (cur-
rently installed in the daemon directory). This file contains the com-
mands that start or stop one Postfix instance, that upgrade the config-
uration of one Postfix instance, and so on.
When the <a href="postfix.1.html">postfix(1)</a> command operates in multi-instance mode as dis-
cussed below, the command needs to execute start, stop, etc. commands
for each Postfix instance. This multiplication of commands is handled
by a multi-instance manager program.
Turning on <a href="postfix.1.html">postfix(1)</a> multi-instance mode goes as follows: in the
default Postfix instance's <a href="postconf.5.html">main.cf</a> file, 1) specify the pathname of a
multi-instance manager program with the <a href="postconf.5.html#multi_instance_wrapper">multi_instance_wrapper</a> parame-
ter; 2) populate the <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> parameter with the con-
figuration directory pathnames of additional Postfix instances. For
example:
/etc/postfix/<a href="postconf.5.html">main.cf</a>:
<a href="postconf.5.html#multi_instance_wrapper">multi_instance_wrapper</a> = $<a href="postconf.5.html#daemon_directory">daemon_directory</a>/postfix-wrapper
<a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> = /etc/postfix-test
The $<a href="postconf.5.html#daemon_directory">daemon_directory</a>/postfix-wrapper file implements a simple manager
and contains instructions for creating Postfix instances by hand. The
<a href="postmulti.1.html">postmulti(1)</a> command provides a more extensive implementation including
support for life-cycle management.
The <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> and other <a href="postconf.5.html">main.cf</a> parameters are listed
below in the CONFIGURATION PARAMETERS section.
In multi-instance mode, the <a href="postfix.1.html">postfix(1)</a> command invokes the
$<a href="postconf.5.html#multi_instance_wrapper">multi_instance_wrapper</a> command instead of the postfix-script file.
This multi-instance manager in turn executes the <a href="postfix.1.html">postfix(1)</a> command in
single-instance mode for each Postfix instance.
To illustrate the main ideas behind multi-instance operation, below is
an example of a simple but useful multi-instance manager implementa-
tion:
#!/bin/sh
: ${<a href="postconf.5.html#command_directory">command_directory</a>?"do not invoke this command directly"}
POSTCONF=$<a href="postconf.5.html#command_directory">command_directory</a>/postconf
POSTFIX=$<a href="postconf.5.html#command_directory">command_directory</a>/postfix
instance_dirs=`$POSTCONF -h <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> |
sed 's/,/ /'` || exit 1
err=0
for dir in $<a href="postconf.5.html#config_directory">config_directory</a> $instance_dirs
do
case "$1" in
stop|abort|flush|reload|drain)
test "`$POSTCONF -c $dir -h <a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a>`" \
= yes || continue;;
start)
test "`$POSTCONF -c $dir -h <a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a>`" \
= yes || {
$POSTFIX -c $dir check || err=$?
continue
};;
esac
$POSTFIX -c $dir "$@" || err=$?
done
exit $err
<b>PER-INSTANCE MULTI-INSTANCE MANAGER CONTROLS</b>
Each Postfix instance has its own <a href="postconf.5.html">main.cf</a> file with parameters that
control how the multi-instance manager operates on that instance. This
section discusses the most important settings.
The setting "<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> = yes" allows the multi-instance
manager to start (stop, etc.) the corresponding Postfix instance. For
safety reasons, this setting is not the default.
The default setting "<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> = no" is useful for manual
testing with "postfix -c <i>/path/name</i> start" etc. The multi-instance
manager will not start such an instance, and it will skip commands such
as "stop" or "flush" that require a running Postfix instance. The
multi-instance manager will execute commands such as "check", "set-per-
missions" or "upgrade-configuration", and it will replace "start" by
"check" so that problems will be reported even when the instance is
disabled.
<b>MAINTAINING SHARED AND NON-SHARED FILES</b>
Some files are shared between Postfix instances, such as executables
and manpages, and some files are per-instance, such as configuration
files, mail queue files, and data files. See the NON-SHARED FILES sec-
tion below for a list of per-instance files.
Before Postfix multi-instance support was implemented, the executables,
manpages, etc., have always been maintained as part of the default
Postfix instance.
With multi-instance support, we simply continue to do this. Specifi-
cally, a Postfix instance will not check or update shared files when
that instance's <a href="postconf.5.html#config_directory">config_directory</a> value is listed with the default
<a href="postconf.5.html">main.cf</a> file's <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> parameter.
The consequence of this approach is that the default Postfix instance
should be checked and updated before any other instances.
<b>MULTI-INSTANCE API SUMMARY</b>
Only the multi-instance manager implements support for the
<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> configuration parameter. The multi-instance man-
ager will start only Postfix instances whose <a href="postconf.5.html">main.cf</a> file has
"<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> = yes". A setting of "no" allows a Postfix
instance to be tested by hand.
The <a href="postfix.1.html">postfix(1)</a> command operates on only one Postfix instance when the
-c option is specified, or when MAIL_CONFIG is present in the process
environment. This is necessary to terminate recursion.
Otherwise, when the <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> parameter value is
non-empty, the <a href="postfix.1.html">postfix(1)</a> command executes the command specified with
the <a href="postconf.5.html#multi_instance_wrapper">multi_instance_wrapper</a> parameter, instead of executing the commands
in postfix-script.
The multi-instance manager skips commands such as "stop" or "reload"
that require a running Postfix instance, when an instance does not have
"<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> = yes". This avoids false error messages.
The multi-instance manager replaces a "start" command by "check" when a
Postfix instance's <a href="postconf.5.html">main.cf</a> file does not have "<a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> =
yes". This substitution ensures that problems will be reported even
when the instance is disabled.
No Postfix command or script will update or check shared files when its
<a href="postconf.5.html#config_directory">config_directory</a> value is listed in the default <a href="postconf.5.html">main.cf</a>'s
<a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> parameter value. Therefore, the default
instance should be checked and updated before any Postfix instances
that depend on it.
Set-gid commands such as <a href="postdrop.1.html">postdrop(1)</a> and <a href="postqueue.1.html">postqueue(1)</a> effectively
append the <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> parameter value to the legacy
<a href="postconf.5.html#alternate_config_directories">alternate_config_directories</a> parameter value. The commands use this
information to determine whether a -c option or MAIL_CONFIG environment
setting specifies a legitimate value.
The legacy <a href="postconf.5.html#alternate_config_directories">alternate_config_directories</a> parameter remains necessary for
non-default Postfix instances that are running different versions of
Postfix, or that are not managed together with the default Postfix
instance.
<b>ENVIRONMENT VARIABLES</b>
MAIL_CONFIG
When present, this forces the <a href="postfix.1.html">postfix(1)</a> command to operate only
on the specified Postfix instance. This environment variable is
exported by the <a href="postfix.1.html">postfix(1)</a> -c option, so that <a href="postfix.1.html">postfix(1)</a> com-
mands in descendant processes will work correctly.
<b>CONFIGURATION PARAMETERS</b>
The text below provides only a parameter summary. See <a href="postconf.5.html">postconf(5)</a> for
more details.
<b><a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a> (empty)</b>
An optional list of non-default Postfix configuration directo-
ries; these directories belong to additional Postfix instances
that share the Postfix executable files and documentation with
the default Postfix instance, and that are started, stopped,
etc., together with the default Postfix instance.
<b><a href="postconf.5.html#multi_instance_wrapper">multi_instance_wrapper</a> (empty)</b>
The pathname of a multi-instance manager command that the <a href="postfix.1.html"><b>post-</b></a>
<a href="postfix.1.html"><b>fix</b>(1)</a> command invokes when the <a href="postconf.5.html#multi_instance_directories">multi_instance_directories</a>
parameter value is non-empty.
<b><a href="postconf.5.html#multi_instance_name">multi_instance_name</a> (empty)</b>
The optional instance name of this Postfix instance.
<b><a href="postconf.5.html#multi_instance_group">multi_instance_group</a> (empty)</b>
The optional instance group name of this Postfix instance.
<b><a href="postconf.5.html#multi_instance_enable">multi_instance_enable</a> (no)</b>
Allow this Postfix instance to be started, stopped, etc., by a
multi-instance manager.
<b>NON-SHARED FILES</b>
<b><a href="postconf.5.html#config_directory">config_directory</a> (see 'postconf -d' output)</b>
The default location of the Postfix <a href="postconf.5.html">main.cf</a> and <a href="master.5.html">master.cf</a> con-
figuration files.
<b><a href="postconf.5.html#data_directory">data_directory</a> (see 'postconf -d' output)</b>
The directory with Postfix-writable data files (for example:
caches, pseudo-random numbers).
<b><a href="postconf.5.html#queue_directory">queue_directory</a> (see 'postconf -d' output)</b>
The location of the Postfix top-level queue directory.
<b>SEE ALSO</b>
<a href="postfix.1.html">postfix(1)</a> Postfix control program
<a href="postmulti.1.html">postmulti(1)</a> full-blown multi-instance manager
$<a href="postconf.5.html#daemon_directory">daemon_directory</a>/postfix-wrapper simple multi-instance manager
<b>LICENSE</b>
The Secure Mailer license must be distributed with this software.
<b>AUTHOR(S)</b>
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
POSTFIX-WRAPPER(5)
</pre> </body> </html>
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