To use the Grok Debugger in Kibana:
1. Access the Grok Debugger You can find the Grok Debugger by navigating to the Developer tools page using the navigation menu or the global search field[1]. For older versions, such as 7.17, open the main menu, click Dev Tools, then click Grok Debugger**[3]. Note that if youâre using Elastic Stack security features, you must have the `manage_pipeline` permission to use the Grok Debugger[1][3].
2. Enter Sample Data In the Sample Data section, enter a message that is representative of the data that you want to parse[1][3]. For example: `55.3.244.1 GET /index.html 15824 0.043`[1].
3. Enter Grok Pattern In the Grok Pattern section, enter the grok pattern that you want to apply to the data[1][3]. To parse the log line in the given example, use: `%{IP:client} %{WORD:method} %{URIPATHPARAM:request} %{NUMBER:bytes} %{NUMBER:duration}`[1].
4. Simulate Click Simulate, and youâll see the simulated event that results from applying the grok pattern[1][3].
You can also test custom patterns[3]:
1. Sample Data Enter your sample message[3]. For example: `Jan 1 06:25:43 mailserver14 postfix/cleanup[21403]: BEF25A72965: message-id=`[3].
2. Grok Pattern Enter your grok pattern[1][3]. For example: `%{SYSLOGBASE} %{POSTFIX_QUEUEID:queue_id}: %{MSG:syslog_message}`. This grok pattern references custom patterns called `POSTFIX_QUEUEID` and `MSG`[3].
3. Custom Patterns Expand the Custom Patterns section, and enter pattern definitions for the custom patterns that you want to use in the grok expression. Specify each pattern definition on its own line[1][3]. For the given example, specify pattern definitions for `POSTFIX_QUEUEID` and `MSG`: `POSTFIX_QUEUEID [0-9A-F]{10,11} MSG message-id=`[1][3].
4. Simulate Click Simulate**[1][3]. Youâll see the simulated output event that results from applying the grok pattern that contains the custom pattern[1]. If an error occurs, you can continue iterating over the custom pattern until the output matches the event that you expect[1][3].
The Grok Debugger simplifies log analysis, allowing you to test and refine Grok patterns before deploying them[5]. Grok is a pattern matching syntax that you can use to parse arbitrary text and structure it[1][3]. It is good for parsing syslog, apache, and other webserver logs, mysql logs, and in general, any log format that is written for human consumption[1][3].
Citations:[1] https://www.elastic.co/guide/en/kibana/current/xpack-grokdebugger.html
[2] https://www.elastic.co/guide/en/elasticsearch/reference/current/grok.html
[3] https://www.elastic.co/guide/en/kibana/7.17/xpack-grokdebugger.html
[4] https://stackoverflow.com/questions/26679465/debugging-new-logstash-grok-filters-before-full-use
[5] https://latenode.com/blog/a-complete-guide-to-using-the-grok-debugger
[6] https://discuss.elastic.co/t/grok-filter-pattern-not-working/211780
[7] https://edgedelta.com/company/blog/what-are-grok-patterns
[8] https://www.elastic.co/guide/en/elasticsearch/reference/current/esql-process-data-with-dissect-and-grok.html
[9] https://www.elastic.co/blog/debugging-broken-grok-expressions-in-elasticsearch-ingest-processors
[10] https://stackoverflow.com/questions/38096827/querying-kibana-using-grok-pattern