Remove_Field json path on logstash

Elastic Stack Logstash
1

Hi comunity,

I'm trying to remove some fileds into a json. The json is:

{"recode":"VZ##","response-code":"4000","response":{"result":[{"DetailsPageURL":"idsource":"0""Attribute":[{"DISPLAYNAME":"Tiempo de respuesta server oasu","Value":"2305"}]}]}}

I just need the fields: DISPLAYNAME and Value. I tried with to diferents configuration files:

input {
  file {
      path => "/mnt/f/user/input/archivo.log"
      type => "json"
      codec=> "json"
      }
}

 filter {
      prune
      {
         whitelist_names => ["Attribute"]
      }
     }

output {
  stdout {
    codec => rubydebug
  }
  
}

i recieve just {} in blank

input {
  file {
      path => "/mnt/f/user/input/archivo.log"
      type => "json"
      codec=> "json"
      }
}

 filter {
      
      json {
        source => "result"
        remove_field => [ "foo_%{DetailsPageURL}", "idsource"]
        
      }}
    

output {
  stdout {
    codec => rubydebug
  }
  
}

and this config dont delete anything.

Thanks for your helps.

2

As the documentation says, prune only operates on top-level fields, so you cannot use it on fields inside [response][result].

Your message is not valid JSON. If I change it to be valid then I can do this:

input { generator { count => 1 lines => [ '{"recode":"VZ##","response-code":"4000","response":{"result":[{"DetailsPageURL":"foo","idsource":"0","Attribute":[{"DISPLAYNAME":"Tiempo de respuesta server oasu","Value":"2305"}]}]}}' ] } }
filter {
    json { source => "message" remove_field => [ "message" ] }
    mutate {
        add_field => {
            "DISPLAYNAME" => "%{[response][result][0][Attribute][0][DISPLAYNAME]}"
            "Value" => "%{[response][result][0][Attribute][0][Value]}"
        }
        remove_field => [ "response" ]
    }
}
output { stdout { codec => rubydebug { metadata => false } } }

which produces

"response-code" => "4000",
        "Value" => "2305",
       "recode" => "VZ##",
  "DISPLAYNAME" => "Tiempo de respuesta server oasu"

You may want to replace the remove_field with a prune using whitelist_names.

If you want to keep those two fields in place then you would need a custom ruby filter. I do not think there is a generic solution to do it that way.

1 Like
3

Great @Badger , i apreciate your answer, thats works perfect.

Just one aditional questions:

I want to export tu csv:

output {
  stdout {
    codec => rubydebug
  }
  csv {
    csv_options => {"headers" => true}
    fields => ["LASTPOLLEDTIME", "[DISPLAYNAME]","[Value]"]
    fields => ["LASTPOLLEDTIME", "[DISPLAYNAME2]","[Value2]"]
    path => "/mnt/f/user/output/archivo.csv"
  }
}

I would like from once call from json, be able to insert the fields in diferents rows, i tried adding "fields" two times, but doesn't work he still add in the same raw.

How can insert into csv file diferentes fields in diferents rows?

Thanks

4

When set an option that expects a hash or array more than once logstash will merge them into a single hash or array.

A csv output will always produce one line per event. The only way I can think of to get multiple lines is something like

input { generator { count => 1 lines => [ '{ "a": 1, "b":2, "c":3, "d":4 }' ] codec => json } }
filter {}
output { stdout { codec => line { format => "%{a},%{b}
%{c},%{d}" } } }

which produces

1,2
3,4

Obviously you would use a file output, not a stdout output.

5

Hi @Badger, thanks for your help,

I could take another path and this works:

output {
  stdout {
    codec => rubydebug
  }
  csv {
    csv_options => {"headers" => true}
    fields => ["LASTPOLLEDTIME", "[DISPLAYNAME]","[Value]"]
    path => "/mnt/f/user/output/archivo.csv"
  }

  csv {
    csv_options => {"headers" => true}
    
    fields => ["LASTPOLLEDTIME", "[DISPLAYNAME2]","[Value2]"]
    path => "/mnt/f/user/output/archivo.csv"
  }
  
}

Thanks for your help and let me know if you think that this path it's ok.

6

I do not know if that will work. Whether two outputs writing to the same file will respect oneanother's positions in the file is really dependent on the operating system and filesystem. I would not expect them to maintain order, either one could write a batch of events first.

1 Like
7

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