Grok function - Simple Log Service - Alibaba Cloud Documentation Center

This topic describes the syntax and parameters of the Grok function. This topic also provides examples on how to use the function.

Description

Regular expression functions are complicated. We recommend that you use the Grok function instead of regular expression functions. For more information, see Regular expression functions. You can use the Grok function together with regular expression functions. Examples:

e_match("content", grok(r"\w+: (%{IP})"))  # The Grok pattern matches the abc: 192.168.0.0 or xyz: 192.168.1.1 pattern of log data. 
e_match("content", grok(r"\w+: (%{IP})", escape=True)) # The Grok pattern does not match the abc: 192.168.0.0 pattern of log data but matches the \w+: 192.168.0.0 pattern of log data.

The Grok function extracts specified values based on a regular expression.

Syntax

grok(pattern, escape=False, extend=None)

Grok syntax
```
%{SYNTAX} 
%{SYNTAX:NAME}
```
In the Grok syntax, SYNTAX specifies a predefined regular expression, and NAME specifies a group. Examples:
```
"%{IP}"               # Equivalent to r"(?:\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})"
"%{IP:source_id}"     # Equivalent to r"(?P<source_id>\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})"
("%{IP}")             # Equivalent to r"(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})"
```
The Grok function supports the following grouping modes:
- Capturing group mode
  Some Grok patterns support named capturing groups. You can use only the %{SYNTAX} syntax for these Grok patterns. These Grok patterns are commonly used to parse statements. For more information, see the "Log formats" section in Grok patterns. Examples:
```
"%{SYSLOGBASE}"        
"%{COMMONAPACHELOG}" 
"%{COMBINEDAPACHELOG}"
"%{HTTPD20_ERRORLOG}"
"%{HTTPD24_ERRORLOG}"
"%{HTTPD_ERRORLOG}"
...
```
- Non-capturing group mode
  Some Grok patterns support non-capturing groups. Examples:
```
"%{INT}"    
"%{YEAR}"
"%{HOUR}"
...
```

Parameters

Parameter	Type	Required	Description
pattern	String	Yes	The Grok syntax. For more information, see Grok patterns.
escape	Bool	No	Specifies whether to escape special characters that are included in regular expressions in non-Grok patterns. Default value: False.
extend	Dict	No	The custom Grok expression.

Examples

Example 1: Extract the date and reference content.

Raw log
```
content: 2019 June 24 "I am iron man"
```

Transformation rule

e_regex('content',grok('%{YEAR:year} %{MONTH:month} %{MONTHDAY:day} %{QUOTEDSTRING:motto}'))

Result

content: 2019 June 24 "I am iron man"
year: 2019
month: June
day: 24
motto: "I am iron man"

Example 2: Extract an HTTP request log.

Raw log

content: 10.0.0.0 GET /index.html 15824 0.043

Transformation rule

e_regex('content',grok('%{IP:client} %{WORD:method} %{URIPATHPARAM:request} %{NUMBER:bytes} %{NUMBER:duration}'))

Result

content: 10.0.0.0 GET /index.html 15824 0.043
client: 10.0.0.0
method: GET
request: /index.html
bytes: 15824
duration: 0.043

Example 3: Extract an Apache log.

Raw log

content: 127.0.0.1 - - [13/Apr/2015:17:22:03 +0800] "GET /router.php HTTP/1.1" 404 285 "-" "curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.15.3 zlib/1.2.3 libidn/1.18 libssh2/1.4.2"

Transformation rule

e_regex('content',grok('%{COMBINEDAPACHELOG}'))

Result

content: 127.0.0.1 - - [13/Apr/2015:17:22:03 +0800] "GET /router.php HTTP/1.1" 404 285 "-" "curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.15.3 zlib/1.2.3 libidn/1.18 libssh2/1.4.2"
clientip: 127.0.0.1
ident: -
auth: -
timestamp: 13/Apr/2015:17:22:03 +0800
verb: GET
request: /router.php
httpversion: 1.1
response: 404
bytes: 285
referrer: "-"
agent: "curl/7.19.7 (x86_64-redhat-linux-gnu) libcurl/7.19.7 NSS/3.15.3 zlib/1.2.3 libidn/1.18 libssh2/1.4.2"

Example 4: Extract a log in the default syslog format.

Raw log

content: May 29 16:37:11 sadness logger: hello world

Transformation rule

e_regex('content',grok('%{SYSLOGBASE} %{DATA:message}'))

Result

content: May 29 16:37:11 sadness logger: hello world
timestamp: May 29 16:37:11
logsource: sadness
program: logger
message: hello world

Example 5: Escape special characters.

Raw log

content: Nov  1 21:14:23 scorn kernel: pid 84558 (expect), uid 30206: exited on signal 3

Transformation rule

e_regex('content',grok(r'%{SYSLOGBASE} pid %{NUMBER:pid} \(%{WORD:program}\), uid %{NUMBER:uid}: exited on signal %{NUMBER:signal}'))

The transformation rule contains special characters parentheses (), which are included in regular expressions. If you do not want to escape the parentheses (), set the escape parameter to True. Example:

e_regex('content',grok('%{SYSLOGBASE} pid %{NUMBER:pid} (%{WORD:program}), uid %{NUMBER:uid}: exited on signal %{NUMBER:signal}', escape=True))

Result

content: Nov  1 21:14:23 scorn kernel: pid 84558 (expect), uid 30206: exited on signal 3
timestamp: Nov  1 21:14:23
logsource: scorn
program: expect
pid: 84558
uid: 30206
signal: 3

Example 6: Extract a log by using a custom Grok expression.

Raw log

content: Beijing-1104,gary 25 "never quit"

Transformation rule

e_regex('content',grok('%{ID:user_id},%{WORD:name} %{INT:age} %{QUOTEDSTRING:motto}',extend={'ID': '%{WORD}-%{INT}'}))

Result

content: Beijing-1104,gary 25 "never quit"
user_id: Beijing-1104
name: gary
age: 25
motto: "never quit"

Example 7: Match JSON data.

Raw log

content: 2019-10-29 16:41:39,218 - INFO: owt.AudioFrameConstructor - McsStats: {"event":"mediaStats","connectionId":"331578616547393100","durationMs":"5000","rtpPackets":"250","rtpBytes":"36945","nackPackets":"0","nackBytes":"0","rtpIntervalAvg":"20","rtpIntervalMax":"104","rtpIntervalVar":"4","rtcpRecvPackets":"0","rtcpRecvBytes":"0","rtcpSendPackets":"1","rtcpSendBytes":"32","frame":"250","frameBytes":"36945","timeStampOutOfOrder":"0","frameIntervalAvg":"20","frameIntervalMax":"104","frameIntervalVar":"4","timeStampIntervalAvg":"960","timeStampIntervalMax":"960","timeStampIntervalVar":"0"}

Transformation rule

e_regex('content',grok('%{EXTRACTJSON}'))

Result

content: 2019-10-29 16:41:39,218 - INFO: owt.AudioFrameConstructor - McsStats: {"event":"mediaStats","connectionId":"331578616547393100","durationMs":"5000","rtpPackets":"250","rtpBytes":"36945","nackPackets":"0","nackBytes":"0","rtpIntervalAvg":"20","rtpIntervalMax":"104","rtpIntervalVar":"4","rtcpRecvPackets":"0","rtcpRecvBytes":"0","rtcpSendPackets":"1","rtcpSendBytes":"32","frame":"250","frameBytes":"36945","timeStampOutOfOrder":"0","frameIntervalAvg":"20","frameIntervalMax":"104","frameIntervalVar":"4","timeStampIntervalAvg":"960","timeStampIntervalMax":"960","timeStampIntervalVar":"0"}
json:{"event":"mediaStats","connectionId":"331578616547393100","durationMs":"5000","rtpPackets":"250","rtpBytes":"36945","nackPackets":"0","nackBytes":"0","rtpIntervalAvg":"20","rtpIntervalMax":"104","rtpIntervalVar":"4","rtcpRecvPackets":"0","rtcpRecvBytes":"0","rtcpSendPackets":"1","rtcpSendBytes":"32","frame":"250","frameBytes":"36945","timeStampOutOfOrder":"0","frameIntervalAvg":"20","frameIntervalMax":"104","frameIntervalVar":"4","timeStampIntervalAvg":"960","timeStampIntervalMax":"960","timeStampIntervalVar":"0"}

Example 8: Parse a log in the World Wide Web Consortium (W3C) format.

Raw log

content: 2018-12-26 00:00:00 W3SVC2 application001 192.168.0.0 HEAD / - 8000 - 10.0.0.0 HTTP/1.0 - - - - 404 0 64 0 19 0

Transformation rule

Fields that are not supported by the W3C format are displayed as hyphens (-). Therefore, hyphens (-) are used in Grok patterns to match the fields.

e_regex("content",grok('%{DATE:data} %{TIME:time} %{WORD:s_sitename} %{WORD:s_computername} %{IP:s_ip} %{WORD:cs_method} %{NOTSPACE:cs_uri_stem} - %{NUMBER:s_port} - %{IP:c_ip} %{NOTSPACE:cs_version} - - - - %{NUMBER:sc_status} %{NUMBER:sc_substatus} %{NUMBER:sc_win32_status} %{NUMBER:sc_bytes} %{NUMBER:cs_bytes} %{NUMBER:time_taken}'))

Result

content: 2018-12-26 00:00:00 W3SVC2 application001 192.168.0.0 HEAD / - 8000 - 10.0.0.0 HTTP/1.0 - - - - 404 0 64 0 19 0 
data: 18-12-26
time: 00:00:00
s_sitename: W3SVC2
s_computername: application001
s_ip: 192.168.0.0
cs_method: HEAD 
cs_uri_stem: /
s_port: 8000
c_ip: 10.0.0.0
cs_version: HTTP/1.0
sc_status: 404
sc_substatus: 0
sc_win32_status: 64 
sc_bytes: 0 
cs_bytes: 19 
time_taken: 0