# Dropping logs in logstash

**URL:** <https://discuss.elastic.co/t/dropping-logs-in-logstash/80665>\
**Category:** Logstash\
**Created:** [March 30, 2017, 11:35am UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665 "2017-03-30T11:35:13Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rupesh\_Ranjan](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rupesh_ranjan/32/22283_2.png) [@Rupesh\_Ranjan](https://discuss.elastic.co/u/Rupesh_Ranjan)\
**Post date:** [March 30, 2017, 11:35am UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/1 "2017-03-30T11:35:13Z")

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Is there any way where i can discard some logs from a log file in case, they match certain query?

for example, i have a log file test-sample.log which has these logs:

1. abc failed due to something
2. warning is generated
3. abc failed due to something

so i want to take whole test-sample.log for log checking, but i want to forward only those lines which contain word "failed" (line 1 and 3 in this case) , to elasticsearch.

---

<div class="post-metadata">

**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [March 30, 2017, 12:02pm UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/2 "2017-03-30T12:02:11Z")

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Use a drop filter and wrap it in a conditional.

```nohighlight
if [fieldname] =~ /failed/ {
  drop { }
}

```

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<div class="post-metadata">

**Author:** ![Rupesh\_Ranjan](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rupesh_ranjan/32/22283_2.png) [@Rupesh\_Ranjan](https://discuss.elastic.co/u/Rupesh_Ranjan)\
**Post date:** [March 30, 2017, 12:45pm UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/3 "2017-03-30T12:45:41Z")

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Wow, That helped. Thanks.

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<div class="post-metadata">

**Author:** ![Rupesh\_Ranjan](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rupesh_ranjan/32/22283_2.png) [@Rupesh\_Ranjan](https://discuss.elastic.co/u/Rupesh_Ranjan)\
**Post date:** [March 31, 2017, 6:38am UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/4 "2017-03-31T06:38:40Z")

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Does that work for regex comparisons too?

e.g.

if [fieldname] =~ /fa\*/ {  
drop { }  
}

P.S. I am using logstash version 5.2.2.

---

<div class="post-metadata">

**Author:** ![magnusbaeck](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/magnusbaeck/32/44943_2.png) [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)\
**Post date:** [March 31, 2017, 6:40am UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/5 "2017-03-31T06:40:36Z")

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Yes, see [https://www.elastic.co/guide/en/logstash/current/event-dependent-configuration.html](https://www.elastic.co/guide/en/logstash/current/event-dependent-configuration.html).

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<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:** [April 28, 2017, 6:40am UTC](https://discuss.elastic.co/t/dropping-logs-in-logstash/80665/6 "2017-04-28T06:40:36Z")

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