# Filter basic file with Logstash

**URL:** <https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991>\
**Category:** Logstash\
**Created:** [December 5, 2021, 8:04pm UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991 "2021-12-05T20:04:13Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![algira37](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/algira37/32/88482_2.png) [@algira37](https://discuss.elastic.co/u/algira37)\
**Post date:** [December 5, 2021, 8:04pm UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991/1 "2021-12-05T20:04:13Z")

</div>

Hello, I have a blocklist.txt which contains IP address in the following structure:  
192.168.100.77  
192.168.100.66

How can I create JSON with Logstash with a similar output:  
{  
IP: 192.168.100.77,  
IP: 192.168.100.66  
}

---

<div class="post-metadata">

**Author:** ![Badger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/badger/32/25190_2.png) [@Badger](https://discuss.elastic.co/u/Badger)\
**Post date:** [December 6, 2021, 12:21am UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991/2 "2021-12-06T00:21:57Z")

</div>

Do you want to convert a set of lines in a file into a single line of JSON? Do you consider duplicate keys to be valid?

---

<div class="post-metadata">

**Author:** ![algira37](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/algira37/32/88482_2.png) [@algira37](https://discuss.elastic.co/u/algira37)\
**Post date:** [December 6, 2021, 5:36pm UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991/3 "2021-12-06T17:36:04Z")

</div>

> [@Badger](#):
>
> Do you want to convert a set of lines in a file into a single line of JSON? Do you consider duplicate keys to be valid?

Not a single JSON line.  
{  
IP: 192.168.100.77,  
},  
{  
IP: 192.168.100.66  
}

---

<div class="post-metadata">

**Author:** ![Badger](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/badger/32/25190_2.png) [@Badger](https://discuss.elastic.co/u/Badger)\
**Post date:** [December 6, 2021, 6:21pm UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991/4 "2021-12-06T18:21:16Z")

</div>

What output are you going to use? It might be as simple as

```
filter { mutate { rename => { "message" => "IP" } } }
output { file { path => "/home/user/foo.txt" codec => json } }
```

---

<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:** [January 3, 2022, 6:21pm UTC](https://discuss.elastic.co/t/filter-basic-file-with-logstash/290991/5 "2022-01-03T18:21:30Z")

</div>

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