背景

Data Lake Analytics (后文简称 DLA)是Serverless化的云上交互式查询分析服务，用户可以通过标准的SQL语句对存储在OSS, OTS, RDS等介质上的数据进行快速地查询分析。

日志文件在大数据分析中的地位举足轻重。对于一个服务来说，其日志文件往往记录了其运行的所有详细信息。无论是故障排除，状态监控，还是预测告警，都离不开对日志文件的查询分析。由于OSS的高性价比，越来越多的用户倾向把大量的日志文件存储在OSS中。DLA可以无需移动OSS上的日志文件，直接对其做查询分析。

本文将介绍如何使用DLA对常见格式的日志文件做查询。

使用DLA查询日志文件

DLA可以分析的日志文件需要满足下面的条件：

日志文件是纯文本的格式，每行可以映射为表中的一条记录；
每行的内容有固定的模式，可以用一个正则表达式去匹配

目前对日志文件的支持还仅限于OSS数据源，因此需要用户预先将日志文件保存于OSS中。

对日志文件建表时，最麻烦的一步就是写正则表达式。下面将以常见的日志文件为例，给出每种文件类型的正则表达式供大家参考。

Apache WebServer 日志

文件内容

127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326
127.0.0.1 - - [26/May/2009:00:00:00 +0000] "GET /someurl/?track=Blabla(Main) HTTP/1.1" 200 5864 - "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.65 Safari/525.19"

正则表达式

([^ ]*) ([^ ]*) ([^ ]*) (-|\\[[^\\]]*\\]) ([^ \"]*|\"[^\"]*\") (-|[0-9]*) (-|[0-9]*)(?: ([^ \"]*|\"[^\"]*\") ([^ \"]*|\"[^\"]*\"))?

建表语句

CREATE EXTERNAL TABLE webserver_log(
  host STRING,
  identity STRING,
  userName STRING,
  time STRING,
  request STRING,
  status STRING,
  size INT,
  referer STRING,
  agent STRING)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.RegexSerDe'
WITH SERDEPROPERTIES (
  "input.regex" = "([^ ]*) ([^ ]*) ([^ ]*) (-|\\[[^\\]]*\\]) ([^ \"]*|\"[^\"]*\") (-|[0-9]*) (-|[0-9]*)(?: ([^ \"]*|\"[^\"]*\") ([^ \"]*|\"[^\"]*\"))?"
)
STORED AS TEXTFILE
LOCATION 'oss://mybucket/datasets/path/to/webserver.log';

查询结果

mysql> select * from webserver_log;
+-----------+----------+-------+------------------------------+---------------------------------------------+--------+------+---------+--------------------------------------------------------------------------------------------------------------------------+
| host      | identity | userName | time                         | request                                     | status | size | referer | agent                                                                                                                    |
+-----------+----------+-------+------------------------------+---------------------------------------------+--------+------+---------+--------------------------------------------------------------------------------------------------------------------------+
| 127.0.0.1 | -        | frank | [10/Oct/2000:13:55:36 -0700] | "GET /apache_pb.gif HTTP/1.0"               | 200    | 2326 | NULL    | NULL                                                                                                                     |
| 127.0.0.1 | -        | -     | [26/May/2009:00:00:00 +0000] | "GET /someurl/?track=Blabla(Main) HTTP/1.1" | 200    | 5864 | -       | "Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US) AppleWebKit/525.19 (KHTML, like Gecko) Chrome/1.0.154.65 Safari/525.19" |
+-----------+----------+-------+------------------------------+---------------------------------------------+--------+------+---------+--------------------------------------------------------------------------------------------------------------------------+

Ngnix访问日志

以NGINX文档中提到的format为例：https://docs.nginx.com/nginx/admin-guide/monitoring/logging/#
文件内容

127.0.0.1 - - [14/May/2018:21:58:04 +0800] "GET /?stat HTTP/1.1" 200 182 "-" "aliyun-sdk-java/2.6.0(Linux/2.6.32-220.23.2.ali927.el5.x86_64/amd64;1.6.0_24)" "-"
127.0.0.1 - - [14/May/2018:21:58:04 +0800] "GET /?prefix=&delimiter=%2F&max-keys=100&encoding-type=url HTTP/1.1" 200 7202 "https://help.aliyun.com/product/70174.html" "aliyun-sdk-java/2.6.0(Linux/2.6.32-220.23.2.ali927.el5.x86_64/amd64;1.6.0_24)" "-"

正则表达式

([^ ]*) ([^ ]*) ([^ ]*) (-|\\[[^\\]]*\\]) (\".*?\") (-|[0-9]*) (-|[0-9]*) ([^ ]*) ([^ ]*) ([^ ]*) (-|\\[[^\\]]*\\]) (\".*?\") (-|[0-9]*) (-|[0-9]*)

建表语句

CREATE EXTERNAL TABLE ngnix_log(
  remote_address STRING,
  identity STRING,
  remote_user STRING,
  time_local STRING,
  request STRING,
  status STRING,
  body_bytes_sent INT,
  http_referer STRING,
  http_user_agent STRING,
  gzip_ratio STRING
)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.RegexSerDe'
WITH SERDEPROPERTIES (
  "input.regex" = "([^ ]*) ([^ ]*) ([^ ]*) (-|\\[[^\\]]*\\]) ([^ \"]*|\"[^\"]*\") (-|[0-9]*) (-|[0-9]*)(?: ([^ \"]*|\"[^\"]*\") ([^ \"]*|\"[^\"]*\"))? ([^ \"]*|\"[^\"]*\")"
)
STORED AS TEXTFILE
LOCATION 'oss://mybucket/datasets/path/to/ngnix_log';

查询结果

mysql> select * from ngnix_log;
+----------------+----------+-------------+------------------------------+-----------------------------------------------------------------------+--------+-----------------+----------------------------------------------+---------------------------------------------------------------------------------+------------+
| remote_address | identity | remote_user | time_local                   | request                                                               | status | body_bytes_sent | http_referer                                 | http_user_agent                                                                 | gzip_ratio |
+----------------+----------+-------------+------------------------------+-----------------------------------------------------------------------+--------+-----------------+----------------------------------------------+---------------------------------------------------------------------------------+------------+
| 127.0.0.1      | -        | -           | [14/May/2018:21:58:04 +0800] | "GET /?stat HTTP/1.1"                                                 | 200    |             182 | "-"                                          | "aliyun-sdk-java/2.6.0(Linux/2.6.32-220.23.2.ali927.el5.x86_64/amd64;1.6.0_24)" | "-"        |
| 127.0.0.1      | -        | -           | [14/May/2018:21:58:04 +0800] | "GET /?prefix=&delimiter=%2F&max-keys=100&encoding-type=url HTTP/1.1" | 200    |            7202 | "https://help.aliyun.com/product/70174.html" | "aliyun-sdk-java/2.6.0(Linux/2.6.32-220.23.2.ali927.el5.x86_64/amd64;1.6.0_24)" | "-"        |
+----------------+----------+-------------+------------------------------+-----------------------------------------------------------------------+--------+-----------------+----------------------------------------------+---------------------------------------------------------------------------------+------------+

Aapache Log4j 日志

以Hadoop默认生成的日志文件为例。
文件内容

2018-11-27 17:45:23,128 INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.AbstractYarnScheduler: Minimum allocation = <memory:1024, vCores:1>
2018-11-27 17:45:23,128 INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.AbstractYarnScheduler: Maximum allocation = <memory:8192, vCores:4>
2018-11-27 17:45:23,154 INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfiguration: max alloc mb per queue for root is undefined
2018-11-27 17:45:23,154 INFO org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfiguration: max alloc vcore per queue for root is undefined

正则表达式

^(\\d{4}-\\d{2}-\\d{2})\\s+(\\d{2}.\\d{2}.\\d{2}.\\d{3})\\s+(\\S+)\\s+(\\S+)\\s+(.*)$

建表语句

CREATE EXTERNAL TABLE log4j_log(
  date STRING,
  time STRING,
  level STRING,
  class STRING,
  details STRING
)
ROW FORMAT SERDE 'org.apache.hadoop.hive.serde2.RegexSerDe'
WITH SERDEPROPERTIES (
  "input.regex" = "^(\\d{4}-\\d{2}-\\d{2})\\s+(\\d{2}.\\d{2}.\\d{2}.\\d{3})\\s+(\\S+)\\s+(\\S+)\\s+(.*)$"
)
STORED AS TEXTFILE
LOCATION 'oss://oss-cn-beijing-for-openanalytics-test-2/datasets/jinluo/nginx/log4j_sample.log';

查询结果

mysql> select * from log4j_log;
+------------+--------------+-------+--------------------------------------------------------------------------------------------------+-------------------------------------------------+
| date       | time         | level | class                                                                                            | details                                         |
+------------+--------------+-------+--------------------------------------------------------------------------------------------------+-------------------------------------------------+
| 2018-11-27 | 17:45:23,128 | INFO  | org.apache.hadoop.yarn.server.resourcemanager.scheduler.AbstractYarnScheduler:                   | Minimum allocation = <memory:1024, vCores:1>    |
| 2018-11-27 | 17:45:23,128 | INFO  | org.apache.hadoop.yarn.server.resourcemanager.scheduler.AbstractYarnScheduler:                   | Maximum allocation = <memory:8192, vCores:4>    |
| 2018-11-27 | 17:45:23,154 | INFO  | org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfiguration: | max alloc mb per queue for root is undefined    |
| 2018-11-27 | 17:45:23,154 | INFO  | org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacitySchedulerConfiguration: | max alloc vcore per queue for root is undefined |
+------------+--------------+-------+--------------------------------------------------------------------------------------------------+-------------------------------------------------+

总结

对于写日志文件的正则表达式：

正则表达式中的每个字段用 () 作为边界，日志中通常每个字段以空格分隔。
建表语句中定义的列的个数要和正则表达式中的字段数完全匹配。
通常，数字可以用 ([0-9]*) 或者 (-|[0-9]*) 匹配，字符串用(¹*) 或者 (".*?") 匹配

使用Data Lake Analytics快速分析OSS上的日志文件

背景

使用DLA查询日志文件

Apache WebServer 日志

Ngnix访问日志

Aapache Log4j 日志

总结

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