# Grok matcher acting strange, works fine in grokconstructor

**URL:** <https://discuss.elastic.co/t/grok-matcher-acting-strange-works-fine-in-grokconstructor/156317>\
**Category:** Logstash\
**Created:** [November 12, 2018, 4:04pm UTC](https://discuss.elastic.co/t/grok-matcher-acting-strange-works-fine-in-grokconstructor/156317 "2018-11-12T16:04:02Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![xeon28](https://avatars.discourse-cdn.com/v4/letter/x/74df32/32.png) [@xeon28](https://discuss.elastic.co/u/xeon28)\
**Post date:** [November 12, 2018, 4:04pm UTC](https://discuss.elastic.co/t/grok-matcher-acting-strange-works-fine-in-grokconstructor/156317/1 "2018-11-12T16:04:02Z")

</div>

I'm using the below pattern to match these example logs:

```
2018-11-12 10:21:33,596[event-thread-1]INFO (HTTP-ENTRY)-ef8684ae-72a4-4ad7-94f9-603e7999b3a4 Get Request to /session with method POST from 10.134.236.205, 169.193.66.107 to 169.193.125.49:8008 return StatusCode 200 process in 34 millionSec client is myclient
2018-11-12 10:21:33,596[event-thread-1]INFO (HTTP-ENTRY)-ef8684ae-72a4-4ad7-94f9-603e7999b3a4 Get Request to /session with method POST from 10.111.236.205 to 169.123.234.49:8008 return StatusCode 200 process in 34 millionSec client is myclient

%{DATESTAMP:timestamp}\[%{DATA:thread}\]%{LOGLEVEL:logLevel}\s*\(%{DATA:program}\)\-%{UUID:id}\s*%{GREEDYDATA}Get Request to\s*%{URIPATHPARAM:request}\s*%{GREEDYDATA}with method\s*%{WORD:method}\s*%{GREEDYDATA}from\s*(?:(?:%{HOSTPORT:client_ip}|%{IP:client_ip})|((?:%{HOSTPORT:forwarding_ip}|%{IP:forwarding_ip}),\s*(?:%{HOSTPORT:client_ip}|%{IP:client_ip})))\s*to\s*(?:%{HOSTPORT:server_ip}|%{IP:server_ip})\s*%{GREEDYDATA}return StatusCode\s*%{NUMBER:statuscode}\s*%{GREEDYDATA}process in\s*%{NUMBER:duration}(?:%{GREEDYDATA}\s*is\s*%{USERNAME:client})?

```

In [http://grokconstructor.appspot.com/do/match](http://grokconstructor.appspot.com/do/match) there is absolutely no problem.

However when there is a "forwarding ip" included in the logs (log line example #1, comma separated IPs) for some reason logstash puts a comma, space then a hyphen after SERVER\_IP... E.G. -\> "169.123.234.49:8008, - "

I have keep\_empty\_captures set to "true".

I cannot explain this behaviour. Any help?

EDIT - checking more logs coming in, it seems to be adding ", -" to IP fields everywhere. Is this something to do with keep\_empty\_captures maybe?

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [December 10, 2018, 4:04pm UTC](https://discuss.elastic.co/t/grok-matcher-acting-strange-works-fine-in-grokconstructor/156317/2 "2018-12-10T16:04:15Z")

</div>

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