elk日志收集之rsyslog软连接监控文件深度坑

业务中通过rsyslog监控本地文件收集了一些redis和mc的慢日志，推到elk集群分析，这些日志一天一个文件，每晚零点5分通过计划任务用软连接的方式将新的文件固定到指定文件下，但是最近发现日志丢了很多，分析中发现了一个深坑，先说下现有的配置：

rsyslog的配置如下，监控固定的文件：

local6.*                                                  @r-log.cms.sina.cn:1514
main_queue(
  queue.workerthreads="10"      # threads to work on the queue
  queue.dequeueBatchSize="1000" # max number of messages to process at once
  queue.size="50000"           # max queue size
)
module(load="imfile")
module(load="omkafka")
$PreserveFQDN on
############################ php curl log #####################################
input(type="imfile"
      File="/data1/ms/log/php_common/php_slow_log"
      Tag="tag1"
      Facility="local5"
      freshStartTail="on"
      deleteStateOnFileDelete="off" 
      reopenOnTruncate="on"  ##日志切割Rsyslog不去读取文件，使用此选项
)
local5.*                                                  @r-log.cms.sina.cn:1515
########################## redis log  ########################################
$template redislog7215,"%$myhostname%`redis7215`%msg%"
ruleset(name="redislog7215") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="redis-log"
        template="redislog7215"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/redis7215.log"
      Tag=""
      ruleset="redislog7215"
      freshStartTail="on"
      reopenOnTruncate="on"
     )
$template redislog7216,"%$myhostname%`redis7216`%msg%"
ruleset(name="redislog7216") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="redis-log"
        template="redislog7216"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/redis7216.log"
      Tag=""
      ruleset="redislog7216"
      freshStartTail="on"
      reopenOnTruncate="on"
     )
$template redislog7242,"%$myhostname%`redis7242`%msg%"
ruleset(name="redislog7242") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="redis-log"
        template="redislog7242"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/redis7242.log"
      Tag=""
      ruleset="redislog7242"
      freshStartTail="on"
      reopenOnTruncate="on"
     )
$template redislog7243,"%$myhostname%`redis7243`%msg%"
ruleset(name="redislog7243") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="redis-log"
        template="redislog7243"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/redis7243.log"
      Tag=""
      ruleset="redislog7243"
      freshStartTail="on"
      reopenOnTruncate="on"
     )
#################### mc .log ###############################
$template mc40016,"%$myhostname%`mc40016`%msg%"
ruleset(name="mc40016") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="cms-front-mc"
        template="mc40016"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/memcached_get_err_40016.log"
      Tag=""
      ruleset="mc40016"
      freshStartTail="on"
      reopenOnTruncate="on"
     )
$template mc40023,"%$myhostname%`mc40023`%msg%"
ruleset(name="mc40023") {
    action(
        broker=["10.13.88.190:9092","10.13.88.191:9092","10.13.88.192:9092","10.13.88.193:9092"]
        type="omkafka"
        topic="cms-front-mc"
        template="mc40023"
        partitions.auto="on"
     )
  }
input(type="imfile"
      File="/data1/ms/log/front/memcached_get_err_40023.log"
      Tag=""
      ruleset="mc40023"
      freshStartTail="on"
      reopenOnTruncate="on"
     )

　　每晚凌晨5分进行计划任务切换，计划任务与脚本如下：

5 0 * * * root sh /usr/local/script/elkslowlog.sh & > /dev/null

　　

#!/bin/bash
DATE=`date +%F`
DATE2=`date +%Y%m%d`
ln -sf  /data1/ms/log/php_common/curl-$DATE  /data1/ms/log/php_common/php_slow_log
ln -sf /data1/ms/log/front/redis7215.$DATE2.log /data1/ms/log/front/redis7215.log
ln -sf /data1/ms/log/front/redis7216.$DATE2.log /data1/ms/log/front/redis7216.log
ln -sf /data1/ms/log/front/redis7242.$DATE2.log /data1/ms/log/front/redis7242.log
ln -sf /data1/ms/log/front/redis7243.$DATE2.log /data1/ms/log/front/redis7243.log
ln -sf /data1/ms/log/front/memcached_get_err_40023.$DATE2.log /data1/ms/log/front/memcached_get_err_40023.log
ln -sf /data1/ms/log/front/memcached_get_err_40016.$DATE2.log /data1/ms/log/front/memcached_get_err_40016.log

　　

问题分析：看着似乎没什么问题，但分析后发现，同样的收集方法，curl的php_slow_log就没有问题，丢日志的mc和redis有个共同特点，就是量不大，有时候半个小时可能就有1条，继续考虑其中的不同，于是想到，可能就是在零点5分创建超连接的瞬间，当天的日志文件还未生成，也就是建立了一个空连接，后面当日志文件真的生成后，rsyslog未检测到超连接对应文件的变化，所以一天的日志都没有，于是测试，果然如此，测试过程不说了。

解决方案：修改脚本文件，在创建超连接时，检测当天日志文件是否生成，如未生成，用echo写入一个空行（空行不会影响收集）生成文件，再进行超连接转换，脚本修改如下

#!/bin/bash
DATE=`date +%F`
DATE2=`date +%Y%m%d`
echo >> /data1/ms/log/php_common/curl-$DATE && ln -sf  /data1/ms/log/php_common/curl-$DATE  /data1/ms/log/php_common/php_slow_log
echo >> /data1/ms/log/front/redis7215.$DATE2.log && ln -sf /data1/ms/log/front/redis7215.$DATE2.log /data1/ms/log/front/redis7215.log
echo >> /data1/ms/log/front/redis7216.$DATE2.log && ln -sf /data1/ms/log/front/redis7216.$DATE2.log /data1/ms/log/front/redis7216.log
echo >> /data1/ms/log/front/redis7242.$DATE2.log && ln -sf /data1/ms/log/front/redis7242.$DATE2.log /data1/ms/log/front/redis7242.log
echo >> /data1/ms/log/front/redis7243.$DATE2.log && ln -sf /data1/ms/log/front/redis7243.$DATE2.log /data1/ms/log/front/redis7243.log
echo >> /data1/ms/log/front/memcached_get_err_40023.$DATE2.log && ln -sf /data1/ms/log/front/memcached_get_err_40023.$DATE2.log /data1/ms/log/front/memcached_get_err_40023.log
echo >> /data1/ms/log/front/memcached_get_err_40016.$DATE2.log && ln -sf /data1/ms/log/front/memcached_get_err_40016.$DATE2.log /data1/ms/log/front/memcached_get_err_40016.log

　　好了，问题圆满解决。