Adding upstream version 3.4.23.upstream/3.4.23upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 113 insertions, 0 deletions

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+PPoossttffiixx llooggggiinngg ttoo ffiillee oorr ssttddoouutt
+
+-------------------------------------------------------------------------------
+
+OOvveerrvviieeww
+
+Postfix supports it own logging system as an alternative to syslog (which
+remains the default). This is available with Postfix version 3.4 or later.
+
+Topics covered in this document:
+
+  * Configuring logging to file
+  * Configuring logging to stdout
+  * Rotating logs
+  * Limitations
+
+CCoonnffiigguurriinngg llooggggiinngg ttoo ffiillee
+
+Logging to file solves a usability problem for MacOS, and eliminates multiple
+problems for systemd-based systems.
+
+ 1. Add the following line to master.cf if not already present (note: there
+    must be no whitespace at the start of the line):
+
+        postlog   unix-dgram n  -       n       -       1       postlogd
+
+    Note: the service type "uunniixx--ddggrraamm" was introduced with Postfix 3.4. Remove
+    the above line before backing out to an older Postfix version.
+
+ 2. Configure Postfix to write logging, to, for example, /var/log/postfix.log.
+    See also the "Logfile rotation" section below for logfile management.
+
+        # postfix stop
+        # postconf maillog_file=/var/log/postfix.log
+        # postfix start
+
+    By default, the logfile name must start with "/var" or "/dev/stdout" (the
+    list of allowed prefixes is configured with the maillog_file_prefixes
+    parameter). This safety mechanism limits the damage from a single
+    configuration mistake.
+
+CCoonnffiigguurriinngg llooggggiinngg ttoo ssttddoouutt
+
+Logging to stdout is useful when Postfix runs in a container, as it eliminates
+a syslogd dependency.
+
+ 1. Add the following line to master.cf if not already present (note: there
+    must be no whitespace at the start of the line):
+
+        postlog   unix-dgram n  -       n       -       1       postlogd
+
+    Note: the service type "uunniixx--ddggrraamm" was introduced with Postfix 3.4. Remove
+    the above line before backing out to an older Postfix version.
+
+ 2. Configure main.cf with "maillog_file = /dev/stdout".
+
+ 3. Start Postfix with "ppoossttffiixx ssttaarrtt--ffgg".
+
+RRoottaattiinngg llooggss
+
+The command "ppoossttffiixx llooggrroottaattee" may be run by hand or by a cronjob. It logs all
+errors, and reports errors to stderr if run from a terminal. This command
+implements the following steps:
+
+  * Rename the current logfile by appending a suffix that contains the date and
+    time. This suffix is configured with the maillog_file_rotate_suffix
+    parameter (default: %Y%m%d-%H%M%S).
+
+  * Reload Postfix so that postlogd(8) immediately closes the old logfile.
+
+  * After a brief pause, compress the old logfile. The compression program is
+    configured with the maillog_file_compressor parameter (default: gzip).
+
+Notes:
+
+  * This command will not rotate a logfile with pathname under the /dev
+    directory, such as /dev/stdout.
+
+  * This command does not (yet) remove old logfiles.
+
+LLiimmiittaattiioonnss
+
+Background:
+
+  * Postfix consists of a number of daemon programs, and non-daemon programs
+    some of which are used for local mail submission, and some for Postfix
+    management.
+
+  * Logging to Postfix logfile or stdout requires the Postfix postlogd(8)
+    service. This ensures that simultaneous logging from different programs
+    will not get mixed up.
+
+  * All Postfix programs can log to syslog, but not all programs have
+    sufficient privileges to use the Postfix logging service, and many non-
+    daemon programs must not log to stdout as that would corrupt their output.
+
+Limitations:
+
+  * Non-daemon Postfix programs will log errors to syslogd(8) before they have
+    processed command-line options and main.cf parameters.
+
+  * If Postfix is down, the non-daemon programs postfix(1), postsuper(1),
+    postmulti(1), and postlog(1), will log directly to $maillog_file. These
+    programs expect to run with root privileges, for example during Postfix
+    start-up, reload, or shutdown.
+
+  * Other non-daemon Postfix programs will never write directly to
+    $maillog_file (also, logging to stdout would interfere with the operation
+    of some of these programs). These programs can log to postlogd(8) if they
+    are run by the super-user, or if their executable file has set-gid
+    permission. Do not set this permission on programs other than postdrop(1)
+    and postqueue(1).
+