# Mutate beats field isnt working in logstash5.0.2
**URL:** https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069
**Category:** Logstash
**Created:** [May 25, 2017, 4:39am UTC](https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069 "2017-05-25T04:39:04Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@sgunnala](https://discuss.elastic.co/u/sgunnala)
#### Post date: [May 25, 2017, 4:39am UTC](https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069/1 "2017-05-25T04:39:04Z")
This pattern in the mutate in logstash.conf isnt working as expected to add hostname as a field. referring to this discussion [Mutate beats field](https://discuss.elastic.co/t/mutate-beats-field/74940) it shows working as expected. Any help greatly appreciated.
mutate { add\_field =\> { "hostname" =\> %{[beat][hostname]} } }
File beats 5.1.1 -\> Kafka 0.9 -\> Logstash 5.0.2
Thanks
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### Author:  [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)
#### Post date: [May 28, 2017, 6:40pm UTC](https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069/2 "2017-05-28T18:40:52Z")
Please show an example event, either as reported by a `stdout { codec => rubydebug }` output or via copy/paste from the JSON tab in Kibana's Discover panel.
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### Author:  [@sgunnala](https://discuss.elastic.co/u/sgunnala)
#### Post date: [May 30, 2017, 1:39pm UTC](https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069/3 "2017-05-30T13:39:41Z")
Thanks Magnus. That worked. adding codec =\>json in input .
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [June 27, 2017, 1:39pm UTC](https://discuss.elastic.co/t/mutate-beats-field-isnt-working-in-logstash5-0-2/87069/4 "2017-06-27T13:39:50Z")
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