rsyslog 不会丢弃消息

Question

我有以下 rsyslog.conf：

$PreserveFQDN on
# rsyslog v5 configuration file

# For more information see /usr/share/doc/rsyslog-*/rsyslog_conf.html
# If you experience problems, see http://www.rsyslog.com/doc/troubleshoot.html

#### MODULES ####

$ModLoad imuxsock # provides support for local system logging (e.g. via logger command)
$ModLoad imklog   # provides kernel logging support (previously done by rklogd)
#$ModLoad immark  # provides --MARK-- message capability

# Provides UDP syslog reception
$ModLoad imudp
$UDPServerRun 514

# Provides TCP syslog reception
$ModLoad imtcp
$InputTCPServerRun 514


#### GLOBAL DIRECTIVES ####

# Use default timestamp format
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat

# File syncing capability is disabled by default. This feature is usually not required,
# not useful and an extreme performance hit
#$ActionFileEnableSync on

# Include all config files in /etc/rsyslog.d/
$IncludeConfig /etc/rsyslog.d/*.conf


#### RULES ####

#discard loadbalancer messages
:msg, contains, "default send string" ~

# Log all kernel messages to the console.
# Logging much else clutters up the screen.
#kern.*                                                 /dev/console

# Log anything (except mail) of level info or higher.
# Don't log private authentication messages!
*.info;mail.none;authpriv.none;cron.none                /var/log/messages

# The authpriv file has restricted access.
authpriv.*                                              /var/log/secure

# Log all the mail messages in one place.
mail.*                                                  -/var/log/maillog


# Log cron stuff
cron.*                                                  /var/log/cron

# Everybody gets emergency messages
*.emerg                                                 *

# Save news errors of level crit and higher in a special file.
uucp,news.crit                                          /var/log/spooler

# Save boot messages also to boot.log
local7.*                                                /var/log/boot.log


# ### begin forwarding rule ###
# The statement between the begin ... end define a SINGLE forwarding
# rule. They belong together, do NOT split them. If you create multiple
# forwarding rules, duplicate the whole block!
# Remote Logging (we use TCP for reliable delivery)
#
# An on-disk queue is created for this action. If the remote host is
# down, messages are spooled to disk and sent when it is up again.
#$WorkDirectory /var/lib/rsyslog # where to place spool files
#$ActionQueueFileName fwdRule1 # unique name prefix for spool files
#$ActionQueueMaxDiskSpace 1g   # 1gb space limit (use as much as possible)
#$ActionQueueSaveOnShutdown on # save messages to disk on shutdown
#$ActionQueueType LinkedList   # run asynchronously
#$ActionResumeRetryCount -1    # infinite retries if host is down
# remote host is: name/ip:port, e.g. 192.168.0.1:514, port optional
#*.* @@remote-host:514
#

*.* @localhost:5000
# ### end of the forwarding rule ###

其中包含以下用于丢弃特定消息的规则：

#discard loadbalancer messages
:msg, contains, "default send string" ~

它似乎没有做它应该做的事情，我仍然可以在 /var/log/messages 中看到这些消息：

[~] # tail -f /var/log/messages
Dec  3 02:51:38 default send string
Dec  3 02:51:42 default send string
Dec  3 02:51:43 default send string
Dec  3 02:51:47 default send string
Dec  3 02:51:48 default send string
Dec  3 02:51:52 default send string
Dec  3 02:51:53 default send string
Dec  3 02:51:57 default send string
Dec  3 02:51:58 default send string
Dec  3 02:52:02 default send string
Dec  3 02:52:03 default send string

请注意，这是一个 Logstash 服务器，它从其他服务器接收 syslog 消息到端口 514，并将它们转发到自己的端口 5000，以便它们被 Logstash 处理，这就是为什么在配置文件中有这一行：

 *.* @localhost:5000

Answer 1

您需要确保丢弃消息的规则应该在将消息写入文件的规则之前调用。

默认情况下，Rsyslog 有一个 /etc/rsyslog.d/50-default.conf 来按原样写入消息。也许把你的规则放在前面：

$IncludeConfig /etc/rsyslog.d/*.conf

应该管用。

Rsyslog 警告不要使用 ~，你应该使用stop代替。

Answer 2

我认为hostname是“默认”，是:msg“发送字符串”，但我也无法让它以这种方式进行过滤。于是，我又做了一些搜索，发现了以下内容：

:rawmsg, isequal, "default send string" stop

这最终让消息消失了。就其价值而言，它们似乎来自我们的负载均衡器，可能是 syslog/udp 运行状况检查。

参考：http://lists.adiscon.net/pipermail/rsyslog/2012-September/030562.html