linux系统日志管理详解

sysklogd 5版本的包名
    syslogd: system application 记录应用日志 
    klogd: linux kernel 记录内核日志

事件记录格式：日期时间 主机 进程[pid]:  事件内容
C/S架构：通过TCP或UDP协议的服务完成日志记录传送，将分布在不同主机的日志实现集中管理

centos6 
[root@centos6 ~]#ps aux |grep syslog   
root       1654  0.0  0.1 249160  1680 ?        Sl   20:28   0:00 /sbin/rsyslogd -i /var/run/syslogd.pid -c 5
root       2381  0.0  0.0 103336   852 pts/0    S+   20:38   0:00 grep syslog
[root@centos6 ~]#which rsyslogd        
/sbin/rsyslogd
[root@centos6 ~]#rpm -qf /sbin/rsyslogd
rsyslog-5.8.10-10.el6_6.x86_64
[root@centos6 ~]#yum info rsyslog-5.8.10-10.el6_6.x86_64
Loaded plugins: fastestmirror, refresh-packagekit, security
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
Installed Packages
Name        : rsyslog
Arch        : x86_64
Version     : 5.8.10
Release     : 10.el6_6
Size        : 2.1 M
Repo        : installed
From repo   : anaconda-CentOS-201703281317.x86_64
Summary     : Enhanced system logging and kernel message trapping daemons
URL         : http://www.rsyslog.com/
License     : (GPLv3+ and ASL 2.0)
Description : Rsyslog is an enhanced, multi-threaded syslog daemon. It supports MySQL,
            : syslog/TCP, RFC 3195, permitted sender lists, filtering on any message part,
            : and fine grain output format control. It is compatible with stock sysklogd
            : and can be used as a drop-in replacement. Rsyslog is simple to set up, with
            : advanced features suitable for enterprise-class, encryption-protected syslog
            : relay chains.
centos7
[root@ ~]#ps aux |grep rsyslogd
root        606  0.0  0.1 216392  4380 ?        Ssl  20:00   0:00 /usr/sbin/rsyslogd -n
root       3586  0.0  0.0 112664   976 pts/0    S+   20:32   0:00 grep --color=auto rsyslogd

[root@ ~]#which rsyslogd                       
/usr/sbin/rsyslogd

[root@ ~]#rpm -qf /usr/sbin/rsyslogd           
rsyslog-8.24.0-12.el7.x86_64

[root@ ~]#yum info rsyslog-8.24.0-12.el7.x86_64
Loaded plugins: fastestmirror, langpacks
Loading mirror speeds from cached hostfile
 * base: mirrors.aliyun.com
 * epel: mirrors.aliyun.com
 * extras: mirrors.aliyun.com
 * updates: mirrors.aliyun.com
Installed Packages
Name        : rsyslog
Arch        : x86_64
Version     : 8.24.0
Release     : 12.el7
Size        : 1.9 M
Repo        : installed
From repo   : anaconda
Summary     : Enhanced system logging and kernel message trapping daemon
URL         : http://www.rsyslog.com/
License     : (GPLv3+ and ASL 2.0)
Description : Rsyslog is an enhanced, multi-threaded syslog daemon. It supports MySQL,
            : syslog/TCP, RFC 3195, permitted sender lists, filtering on any message part,
            : and fine grain output format control. It is compatible with stock sysklogd
            : and can be used as a drop-in replacement. Rsyslog is simple to set up, with
            : advanced features suitable for enterprise-class, encryption-protected syslog
            : relay chains.

rsyslog CentOS 6~7版本的包名
rsyslog特性:
    多线程
    支持UDP, TCP, SSL, TLS, RELP
    支持MySQL, PGSQL, Oracle实现日志存储
    强大的过滤器，可实现过滤记录日志信息中任意部分
    自定义输出格式
ELK：elasticsearch, logstash, kibana(日志分析系统，三款开源产品名称的首字母集合)
    Elasticsearch是个开源分布式搜索引擎
    Logstash对日志进行收集、分析，并将其存储供以后使用
    kibana 可以提供的日志分析友好的Web界面
    非关系型分布式数据库
    基于apache软件基金会jakarta项目组的项目lucene

术语，参见man logger
    facility：设施，从功能或程序上对日志进行归类
        auth       #验证 已弃用使用
        authpriv   #授权
        cron       #计划任务
        daemon     #守护进程
        ftp 
        kern 
        lpr        #打印 
        mail 
        news
        security(auth)  #安全
        user
        uucp
        local0-local7   #自定义
        syslog
    Priority 优先级别，从低到高排序
        debug          #适用于调试什么都记录
        info           #记录相对重要的
        notice         #重要通知    
        warn(warning)  #警报快出错
        err(error)     #报错
        crit(critical) #临界
        alert          #警觉的
        emerg(panic)   #彻底崩溃了   
例：如果是info(它包括notice, warn(warning), err(error), crit(critical), alert, emerg(panic))，只记录优先级高的，不记录优先级低的
参看帮助：man 3 syslog

程序包：rsyslog
主程序：/usr/sbin/rsyslogd
CentOS 6：service rsyslog{start|stop|restart|status}
CentOS 7：/usr/lib/systemd/system/rsyslog.service
配置文件：/etc/rsyslog.conf，/etc/rsyslog.d/*.conf
库文件：/lib64/rsyslog/*.so 
配置文件格式：由三部分组成
    MODULES：相关模块配置
    GLOBAL DIRECTIVES：全局配置
    RULES：日志记录相关的规则配置
日志滚动配置文件：/etc/logrotate.d/syslog 

RULES配置格式：
    facility.priority facility.priority... target
facility：
    *: 所有的facility  
    facility1,facility2,facility3,...：指定的facility列表
priority：
    *: 所有级别
    none：没有级别，即不记录
    PRIORITY：指定级别（含）以上的所有级别
    =PRIORITY：仅记录指定级别的日志信息
target：
    文件路径：通常在/var/log/，文件路径前的"-"表示异步写入
    用户：将日志事件通知给指定的用户，* 表示登录的所有用户
    日志服务器：@host，把日志送往至指定的远程服务器记录
    管道：| COMMAND，转发给其它命令处理

# 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 #### # 模块

$ModLoad imuxsock # provides support for local system logging (e.g. via logger command) # 支持本地系统日志记录（例如通过logger命令）
$ModLoad imklog   # provides kernel logging support (previously done by rklogd) # 提供内核日志记录支持（以前由rklogd完成）
#$ModLoad immark  # provides --MARK-- message capability # 提供了--MARK--消息功能

# Provides UDP syslog reception # 提供UDP系统日志接收
#$ModLoad imudp
#$UDPServerRun 514

# Provides TCP syslog reception # 提供TCP系统日志接收
#$ModLoad imtcp
#$InputTCPServerRun 514


#### GLOBAL DIRECTIVES #### # 全局设置

# Use default timestamp format # 使用默认的时间戳格式
$ActionFileDefaultTemplate RSYSLOG_TraditionalFileFormat

# File syncing capability is disabled by default. This feature is usually not required, # 文件同步功能默认是关闭的。这个功能通常不是必需的
# not useful and an extreme performance hit
#$ActionFileEnableSync on

# Include all config files in /etc/rsyslog.d/ # 将所有配置文件包含在/etc/rsyslog.d/中
$IncludeConfig /etc/rsyslog.d/*.conf


#### RULES #### # 规则

# Log all kernel messages to the console. # 将所有内核消息记录到控制台 
# Logging much else clutters up the screen.
#kern.*                                                 /dev/console

# Log anything (except mail) of level info or higher. # 记录级别信息或更高级别的任何信息（邮件除外）
# Don't log private authentication messages! # 不要记录私人认证信息！
*.info;mail.none;authpriv.none;cron.none                /var/log/messages
# 记录info级别的日志信息 排除mail authpriv cron
# The authpriv file has restricted access. # authpriv文件具有受限制的访问权限。
authpriv.*                                              /var/log/secure

# Log all the mail messages in one place. # 将所有的邮件记录在一个地方。
mail.*                                                  -/var/log/maillog
# -/var/log/maillog 前面"-"是：代表异步写入,邮件量大占I/O在系统不忙时做

# Log cron stuff # 日志计划任务的东西
cron.*                                                  /var/log/cron

# Everybody gets emergency messages # 每用户都得到紧急消息
*.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  # 将启动信息保存到boot.log 只记录当前系统启动日志
local7.*                                                /var/log/boot.log


# ### begin forwarding rule ### # 开始转发规则
# 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
# ### end of the forwarding rule ### 转发规则结束

[root@centos6 ~]#vim /etc/ssh/sshd_config
SyslogFacility AUTHPRIV 
# /etc/ssh/sshd_config 文件36行处sshd定义AUTHPRIV -> facility
# 而facility 在 /etc/rsyslog.conf 文件45行处 定义了级别
[root@centos6 ~]#vim /etc/rsyslog.conf
authpriv.*                               /var/log/secure
# 所以/var/log/secure此文件里面定义了sshd的日志

sshd服务单独放单到一个文件中
先修改/etc/rsyslog.conf #约62行
[root@centos6 ~]#vim /etc/rsyslog.conf
local7.*                               /var/log/boot.log
local0.*                               /var/log/sshd.log 
# 这里需确定local0没人用

之后修改此文件 /etc/ssh/sshd_config

[root@centos6 ~]#vim /etc/ssh/sshd_config
SyslogFacility AUTHPRIV 
# SyslogFacility local0 (AUTHPRIV 修改为local0  即可 )

最后重新启动rsyslog sshd服务即可

给单独用户发消息
先修改/etc/rsyslog.conf #约62行
[root@centos6 ~]#vim /etc/rsyslog.conf
local7.*                               /var/log/boot.log
local0.*                               zhang,root 
[root@centos6 ~]#logger -p local0.info "This is a test log" 
# 执行此命令root和zhang都能收到This is a test log消息，前提是在线
# zhang,root换成"*" 是通知所有在线的用户

通常的日志格式：
    事件产生的日期时间 主机 进程(pid)：事件内容 
    如：/var/log/messages,cron,secure等

配置rsyslog成为日志服务器
#### MODULES ####
# Provides UDP syslog reception
$ModLoadimudp
$UDPServerRun514

# Provides TCP syslog reception
$ModLoadimtcp
$InputTCPServerRun514

centos 7 上操作打开 udp514端口

注意服务器的防火墙别屏蔽
    iptables -vnL # 查看防火墙 
    iptables -F   # 这里我们把它清空
[root@centos7 ~]#vim /etc/rsyslog.conf
$ModLoad imudp                                                                              
$UDPServerRun 514
# 15~16行去掉注释 打开udp514端口
# systemctl restart rsyslog # 重新启动rsyslog 
# ss -ntlpu |grep 514  #查看是否打开udp514端口

centos 6上操作

先修改/etc/rsyslog.conf #约42行
[root@centos6 ~]#vim /etc/rsyslog.conf
*.info;mail.none;authpriv.none;cron.none     /var/log/messages
*.info;mail.none;authpriv.none;cron.none      @172.18.2.232   
# /var/log/messages 路径修改为目标主机@172.18.2.232
# systemctl restart rsyslog # 重新启动rsyslog 
# 效果是本地存一份 远程主机172.18.2.232存一份

centos 7 先打开监控/var/log/messages这个文件
[root@centos7 ~]#tail -f /var/log/messages

centos 6 测试日志
[root@centos6 ~]#logger "This is a test log"

测试成功
[root@centos7 ~]#tail -f /var/log/messages
Feb  1 15:27:29 centos6 root: This is a test log
[root@centos6 ~]#tail -f /var/log/messages
Feb  1 15:27:29 centos6 root: This is a test log

centos 6上操作

先修改/etc/rsyslog.conf #约42行
[root@centos6 ~]#vim /etc/rsyslog.conf
*.info;mail.none;authpriv.none;cron.none     /var/log/messages
*.info;mail.none;authpriv.none;cron.none     @@172.18.2.232   

systemctl restart rsyslog # 重新启动rsyslog 
[root@centos6 ~]#logger "This is a test log"
与UDP步骤一样

查看系统启动多长时间
[root@centos7 ~]#uptime 
 16:10:59 up  4:34,  1 user,  load average: 0.00, 0.01, 0.05

系统启动开始时间
[root@centos7 ~]#ll /var/log/boot.log  
-rw-------. 2 root root 27581 Feb  1 16:15 /var/log/boot.log

可以查看到启动信息(比如rsyslogd就可以看到开始启动时间)
[root@centos7 ~]#grep rsyslogd /var/log/messages
Feb  1 16:14:57 centos7 rsyslogd: [origin software="rsyslogd" swVersion="8.24.0" x-pid="600" x-info="http://www.rsyslog.com"] start

journalctl

journalctl -k

journalctl -b
journalctl -b -0

journalctl -b -1

journalctl --since="2017-10-30 18:10:30"
journalctl --since "20 min ago"
journalctl --since yesterday
journalctl --since "2017-01-10" --until "2017-01-11 03:00"
journalctl --since 09:00 --until "1 hour ago"

journalctl -n

journalctl -n 20

journalctl -f

journalctl /usr/lib/systemd/systemd

journalctl _PID=1

journalctl /usr/bin/bash

journalctl _UID=33 --since today

journalctl -u nginx.service
journalctl -u nginx.service --since today

journalctl -u nginx.service -f

journalctl -u nginx.service -u php-fpm.service --since today

查看指定优先级（及其以上级别）的日志，共有8级
0: emerg
1: alert
2: crit
3: err
4: warning
5: notice
6: info
7: debug
    journalctl -p err -b

journalctl --no-pager 

journalctl -b -u nginx.service -o json

journalctl -b -u nginx.serviceqq -o json-pretty

journalctl --disk-usage

journalctl --vacuum-size=1G

journalctl --vacuum-time=1years