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3.1 Nginx访问日志
访问日志处理分析绝对是使用ELK stack时最常见的需求。默认的处理方式下，性能和精确度都不够好。本节会列举对Nginx访问日志的几种不同处理方式，并阐明其优劣。
3.1.1 grok处理方式
Logstash默认自带了Apache标准日志的grok正则：
COMMONAPACHELOG %{IPORHOST:clientip} %{USER:ident} %{NOTSPACE:auth}\[%{HTTPDATE:
timestamp}\] “（？：%{WORD:verb} %{NOTSPACE:request}（？： HTTP/%{NUMBER:httpversion}）？
|%{DATA:rawrequest}）” %{NUMBER:response} （？：%{NUMBER:bytes}|-）
COMBINEDAPACHELOG %{COMMONAPACHELOG} %{QS:referrer} %{QS:agent}
对于Nginx标准日志格式，可以发现只是最后多了一个$http_x_forwarded_for变量。所以Nginx标准日志的grok正则定义是：
MAINNGINXLOG %{COMBINEDAPACHELOG} %{QS:x_forwarded_for}
自定义的日志格式，可以照此修改。
3.1.2 split处理方式
Nginx日志因为部分变量中内含空格，所以很多时候只能使用%{QS}正则来做分隔，性能和细度都不太好。如果能自定义一个比较少见的字符作为分隔符，那么处理起来就简单多了。假设定义的日志格式如下：
log_format main “$http_x_forwarded_for | $time_local | $request | $status |
$body_bytes_sent | ”“$request_body | $content_length | $http_referer | $http_user_agent | $nuid | ”“$http_cookie | $remote_addr | $hostname | $upstream_addr | $upstream_response_
time | $request_time”;
实际日志如下：
117.136.9.248 | 08/Apr/2015:16:00:01 +0800 | POST /notice/newmessage?sign=cba4f614e05db285850cadc696fcdad0&token=JAGQ92Mjs3--gik_b_DsPIQHcyMKYGpD&did=b749736ac70f12df700b18cd6d051d5&osn=android&osv=4.0.4&appv=3.0.1&net=460-02-2g&longitude=120.393006&latitude=36.178329&ch=360&lp=1&ver=1&ts=1428479998151&im=869736012353958&sw=0&sh=0&la=zh-CN&lm=weixin&dt=vivoS11tHTTP/1.1| 200 | 132 | abcd-sign-v1://dd03c57f8cb6fcef919ab5df66f2903f:d51asq5yslwnyz5t/{\x22type\x22:4,\x22uid\x22:7567306} | 89 | - | abcd/3.0.1, Android/4.0.4, vivo S11t | nuid=0C0A0A0A01E02455EA7CF47E02FD072C1428480001.157| - | 10.10.10.13 | bnx02.abcdprivate.com | 10.10.10.22:9999 | 0.022 | 0.022 59.50.44.53 | 08/Apr/2015:16:00:01 +0800 | POST /feed/pubList?appv=3.0.3&did=89da72550de488328e2aba5d97850e9f&dt=iPhone6%2C2&im=B48C21F3-487E-4071-9742-DC6D61710888&la=cn&latitude=0.000000&lm=weixin&longitude=0.000000&lp=-1.000000&net=0-0-wifi&osn=iOS&osv=8.1.3&sh=568.000000&sw=320.000000&token=7NobA7asg3Jb6n9o4ETdPXyNNiHwMs4J&ts=1428480001275 HTTP/1.1 | 200 | 983 | abcd-sign-v1://b398870a0b25b29aae65cd553addc43d:72214ee85d7cca22/{\x22nextkey\x22:\x22\x22,\x22uid\x22:\x2213062545\x22,\x22token\x22:\x227NobA7asg3Jb6n9o4ETdPXyNNiHwMs4J\x22}| 139 | - | Shopping/3.0.3 （iPhone; iOS 8.1.3; Scale/2.00） | nuid=0C0A0A0A81-DF2455017D548502E48E2E1428480001.154 | nuid=CgoKDFUk34GFVH0BLo7kAg== | 10.10.10.11 | bnx02.abcdprivate.com | 10.10.10.35:9999 | 0.025 | 0.026
然后还可以针对request做更细致的切分。比如URL参数部分。很明显，URL参数中的字段顺序是乱的。第一行问号之后的第一个字段是sign，第二行问号之后的第一个字段是appv。所以需要将字段进行切分，取出每个字段对应的值。官方自带grok满足不了要求，最终采用的Logstash配置如下：
filter {
ruby {
init =>“@kname =['http_x_forwarded_for','time_local','request','status',
'body_bytes_sent','request_body','content_length','http_referer','http_
user_agent','nuid','http_cookie','remote_addr','hostname','upstream_
addr','upstream_response_time','request_time']”
code =>“event.append（Hash[@kname.zip（event['message'].split（‘ | ’））]）”
}
if [request] {
ruby {
init =>“@kname = ['method','uri','verb']”
code =>“event.append（Hash[@kname.zip（event['request'].split（‘ ’））]）”
}
if [uri] {
ruby {
init =>“@kname = ['url_path','url_args']”
code =>“event.append（Hash[@kname.zip（event['request'].split（‘?’））]）”
}
kv {
prefix =>“url_”
source =>“url_args”
field_split =>“&”
remove_field => [ “url_args”,“uri”,“request” ]
}
}
}
mutate {
convert => [“body_bytes_sent” , “integer”,“content_length”, “integer”,“upstream_response_time”, “float”,“request_time”, “float”
]
}
date {
match => [ “time_local”, “dd/MMM/yyyy:hh:mm:ss Z” ]
locale =>“en”
}
}
最终结果如下：
{“message” =>“1.43.3.188 | 08/Apr/2015:16:00:01 +0800 | POST /search/sug
gest?appv=3.0.3&did=dfd5629d705d400795f698055806f01d&dt=iPhone7%2C2&im=
AC926907-27AA-4A10-9916-C5DC75F29399&la=cn&latitude=-33.903867&lm=
sina&longitude=151.208137&lp=-1.000000&net=0-0-wifi&osn=iOS&osv=8.1.3&sh=66
7.000000&sw=375.000000&token=_ovaPz6Ue68ybBuhXustPbG-xf1WbsPO&ts=
1428480001567 HTTP/1.1 | 200 | 353 | abcd-sign-v1://a24b478486d3bb92ed89a-
901541b60a5:b23e9d2c14fe6755/{\\x22key\\x22:\\x22last\\x22,\\x22offset\\x22:
\\x220\\x22,\\x22token\\x22:\\x22_ovaPz6Ue68ybBuhXustPbG-xf1WbsPO\\x22,
\\x22limit\\x22:\\x2220\\x22} | 148 | - | abcdShopping/3.0.3 （iPhone; iOS
8.1.3; Scale/2.00） | nuid=0B0A0A0A9A64AF54F97634640230944E1428480001.113
| nuid=CgoKC1SvZJpkNHb5TpQwAg== | 10.10.10.11 | bnx02.abcdprivate.com |
10.10.10.26:9999 | 0.070 | 0.071”,“@version” =>“1”,“@timestamp” =>“2015-04-08T08:00:01.000Z”,“type” =>“nginxapiaccess”,“host” =>“blog05.abcdprivate.com”,“path” =>“/home/nginx/logs/api.access.log”,“http_x_forwarded_for” =>“1.43.3.188”,“time_local” =>“ 08/Apr/2015:16:00:01 +0800”,“status” =>“200”,“body_bytes_sent” => 353,“request_body” =>“abcd-sign-v1://a24b478486d3bb92ed89a901541b60a5:b23e9d2c1
4fe6755/{\\x22key\\x22:\\x22last\\x22,\\x22offset\\x22:\\x220\\x22,\\x22token
\\x22:\\x22_ovaPz6Ue68ybBuhXustPbG-xf1WbsPO\\x22,\\x22limit\\x22:\\x2220\\x22}”,“content_length” => 148,“http_referer” =>“-”,“http_user_agent” =>“abcdShopping/3.0.3 （iPhone; iOS 8.1.3; Scale/2.00）”,“nuid” =>“nuid=0B0A0A0A9A64AF54F97634640230944E1428480001.113”,“http_cookie” =>“nuid=CgoKC1SvZJpkNHb5TpQwAg==”,“remote_addr” =>“10.10.10.11”,“hostname” =>“bnx02.abcdprivate.com”,“upstream_addr” =>“10.10.10.26:9999”,“upstream_response_time” => 0.070,“request_time” => 0.071,“method” =>“POST”,“verb” =>“HTTP/1.1”,“url_path” =>“/search/suggest”,“url_appv” =>“3.0.3”,“url_did” =>“dfd5629d705d400795f698055806f01d”,“url_dt” =>“iPhone7%2C2”,“url_im” =>“AC926907-27AA-4A10-9916-C5DC75F29399”,“url_la” =>“cn”,“url_latitude” =>“-33.903867”,“url_lm” =>“sina”,“url_longitude” =>“151.208137”,“url_lp” =>“-1.000000”,“url_net” =>“0-0-wifi”,“url_osn” =>“iOS”,“url_osv” =>“8.1.3”,“url_sh” =>“667.000000”,“url_sw” =>“375.000000”,“url_token” =>“_ovaPz6Ue68ybBuhXustPbG-xf1WbsPO”,“url_ts” =>“1428480001567”
}
如果URL参数过多，可以不使用kv切分，或者预先定义成nested object后改成数组形式：
if [uri] {
ruby {
init =>“@kname = ['url_path','url_args']”
code =>“event.append（Hash[@kname.zip（event['request'].split（‘?’））]）”
}
if [url_args] {
ruby {
init =>“@kname = ['key','value']”
code =>“event['nested_args'] = event['url_args'].split（‘&’）。collect
{|i| Hash[@kname.zip（i.split（‘=’））]}”
remove_field => [ “url_args”,“uri”,“request” ]
}
}
}
采用nested object的优化原理和nested object的使用方式，请阅读后面Elasticsearch调优章节。
3.1.3 json格式
自定义分隔符虽好，但是配置写起来毕竟复杂很多。其实对Logstash来说，Nginx日志还有另一种更简便的处理方式，就是自定义日志格式时，通过手工拼写直接输出成JSON格式：
log_format json '{“@timestamp”:“$time_iso8601”,'
‘“host”:“$server_addr”,'
’“clientip”:“$remote_addr”,'
‘“size”:$body_bytes_sent,'
’“responsetime”:$request_time,'
‘“upstreamtime”:“$upstream_response_time”,'
’“upstreamhost”:“$upstream_addr”,'
‘“http_host”:“$host”,'
’“url”:“$uri”,'
‘“xff”:“$http_x_forwarded_for”,'
’“referer”:“$http_referer”,'
‘“agent”:“$http_user_agent”,'
’“status”:“$status”}';
然后采用下面的Logstash配置即可：
input {
file {
path =>“/var/log/nginx/access.log”
codec => json
}
}
filter {
mutate {
split => [ “upstreamtime”, “,” ]
}
mutate {
convert => [ “upstreamtime”, “float” ]
}
}
这里采用多个mutate插件，是因为upstreamtime可能有多个数值，所以先切割成数组以后，再分别转换成浮点型数值。而在mutate中，convert函数的执行优先级高于split函数，所以只能分开两步写。mutate内各函数的优先级顺序，之前插件介绍章节有详细说明，读者可以返回去阅读。
3.1.4 syslog方式发送
Nginx从1.7版开始，加入了syslog支持，Tengine则更早。这样，我们可以通过syslog直接发送日志。Nginx上的配置如下：
access_log syslog:server=unix:/data0/rsyslog/nginx.sock locallog;
或者直接发送给远程Logstash机器：
access_log syslog:server=192.168.0.2:5140,facility=local6,tag=nginx-access,
severity=info logstashlog;
默认情况下，Nginx将使用local7.info等级，以nginx为标签发送数据。注意，采用syslog发送日志的时候，无法配置buffer=16k选项。