# Logstash parse only JSON messages

**URL:** <https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103>\
**Category:** Logstash\
**Created:** [May 31, 2018, 7:36pm UTC](https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103 "2018-05-31T19:36:07Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ArunANayagam](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/arunanayagam/32/45171_2.png) [@ArunANayagam](https://discuss.elastic.co/u/ArunANayagam)\
**Post date:** [May 31, 2018, 7:36pm UTC](https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103/1 "2018-05-31T19:36:07Z")

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Hi,  
I want to parse various different messages being logged into cloudwatch. And I am planning to use logstash-input-cloudwatch-logs plugin.

Now there are a lot of non-json messages written into cloudwatch, I want to ignore all of them. I only want proper json messages to be parsed.

I know that I can use the json filter and drop messages that have a tag of "\_jsonparsefailure"

But somehow this feels inefficient, as the attempt to json parse is done and then a decision to drop is made.

Is there a more efficient way to drop non-json messages?

Thanks,  
Arun

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<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:** [May 31, 2018, 8:57pm UTC](https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103/2 "2018-05-31T20:57:37Z")

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Well, you could use a conditional that drops all events that don't begin with `{`.

```nohighlight
if [message] !~ /^\{/ {
  drop { }
}

```

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<div class="post-metadata">

**Author:** ![ArunANayagam](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/arunanayagam/32/45171_2.png) [@ArunANayagam](https://discuss.elastic.co/u/ArunANayagam)\
**Post date:** [June 1, 2018, 9:04am UTC](https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103/3 "2018-06-01T09:04:46Z")

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Thank you so much. That helps.

Arun

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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:** [June 29, 2018, 9:04am UTC](https://discuss.elastic.co/t/logstash-parse-only-json-messages/134103/4 "2018-06-29T09:04:51Z")

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