Mutate filter plugin

Mutations in a config file are executed in this order:

Example:

filter {
    mutate {
        split => { "hostname" => "." }
        add_field => { "shortHostname" => "%{[hostname][0]}" }
    }

    mutate {
        rename => {"shortHostname" => "hostname"}
    }
}

Convert a field’s value to a different type, like turning a string to an integer. If the field value is an array, all members will be converted. If the field is a hash no action will be taken.

Valid conversion targets, and their expected behaviour with different inputs are:

This plugin can convert multiple fields in the same document, see the example below.

Example:

    filter {
      mutate {
        convert => {
          "fieldname" => "integer"
          "booleanfield" => "boolean"
        }
      }
    }

Copy an existing field to another field. Existing target field will be overriden.

Example:

    filter {
      mutate {
         copy => { "source_field" => "dest_field" }
      }
    }

Match a regular expression against a field value and replace all matches with a replacement string. Only fields that are strings or arrays of strings are supported. For other kinds of fields no action will be taken.

This configuration takes an array consisting of 3 elements per field/substitution.

Be aware of escaping any backslash in the config file.

Example:

    filter {
      mutate {
        gsub => [
          # replace all forward slashes with underscore
          "fieldname", "/", "_",
          # replace backslashes, question marks, hashes, and minuses
          # with a dot "."
          "fieldname2", "[\\?#-]", "."
        ]
      }
    }

Join an array with a separator character or string. Does nothing on non-array fields.

Example:

   filter {
     mutate {
       join => { "fieldname" => "," }
     }
   }

Convert a string to its lowercase equivalent.

Example:

    filter {
      mutate {
        lowercase => [ "fieldname" ]
      }
    }

Merge two fields of arrays or hashes. String fields will be automatically be converted into an array, so:

`array` + `string` will work
`string` + `string` will result in an 2 entry array in `dest_field`
`array` and `hash` will not work

Example:

    filter {
      mutate {
         merge => { "dest_field" => "added_field" }
      }
    }

Set the default value of a field that exists but is null

Example:

    filter {
      mutate {
        # Sets the default value of the 'field1' field to 'default_value'
        coerce => { "field1" => "default_value" }
      }
    }

Rename one or more fields.

If the destination field already exists, its value is replaced.

If one of the source fields doesn’t exist, no action is performed for that field. (This is not considered an error; the tag_on_failure tag is not applied.)

When renaming multiple fields, the order of operations is not guaranteed.

Example:

    filter {
      mutate {
        # Renames the 'HOSTORIP' field to 'client_ip'
        rename => { "HOSTORIP" => "client_ip" }
      }
    }

Replace the value of a field with a new value, or add the field if it doesn’t already exist. The new value can include %{foo} strings to help you build a new value from other parts of the event.

Example:

    filter {
      mutate {
        replace => { "message" => "%{source_host}: My new message" }
      }
    }

Split a field to an array using a separator character or string. Only works on string fields.

Example:

    filter {
      mutate {
         split => { "fieldname" => "," }
      }
    }

Strip whitespace from field. NOTE: this only works on leading and trailing whitespace.

Example:

    filter {
      mutate {
         strip => ["field1", "field2"]
      }
    }

Update an existing field with a new value. If the field does not exist, then no action will be taken.

Example:

    filter {
      mutate {
        update => { "sample" => "My new message" }
      }
    }

Convert a string to its uppercase equivalent.

Example:

    filter {
      mutate {
        uppercase => [ "fieldname" ]
      }
    }

Convert a string to its capitalized equivalent.

Example:

    filter {
      mutate {
        capitalize => [ "fieldname" ]
      }
    }

If a failure occurs during the application of this mutate filter, the rest of the operations are aborted and the provided tag is added to the event.

If this filter is successful, add any arbitrary fields to this event. Field names can be dynamic and include parts of the event using the %{field}.

Example:

    filter {
      mutate {
        add_field => { "foo_%{somefield}" => "Hello world, from %{host}" }
      }
    }

    # You can also add multiple fields at once:
    filter {
      mutate {
        add_field => {
          "foo_%{somefield}" => "Hello world, from %{host}"
          "new_field" => "new_static_value"
        }
      }
    }

If the event has field "somefield" == "hello" this filter, on success, would add field foo_hello if it is present, with the value above and the %{host} piece replaced with that value from the event. The second example would also add a hardcoded field.

If this filter is successful, add arbitrary tags to the event. Tags can be dynamic and include parts of the event using the %{field} syntax.

Example:

    filter {
      mutate {
        add_tag => [ "foo_%{somefield}" ]
      }
    }

    # You can also add multiple tags at once:
    filter {
      mutate {
        add_tag => [ "foo_%{somefield}", "taggedy_tag"]
      }
    }

If the event has field "somefield" == "hello" this filter, on success, would add a tag foo_hello (and the second example would of course add a taggedy_tag tag).

Disable or enable metric logging for this specific plugin instance. By default we record all the metrics we can, but you can disable metrics collection for a specific plugin.

Add a unique ID to the plugin configuration. If no ID is specified, Logstash will generate one. It is strongly recommended to set this ID in your configuration. This is particularly useful when you have two or more plugins of the same type, for example, if you have 2 mutate filters. Adding a named ID in this case will help in monitoring Logstash when using the monitoring APIs.

    filter {
      mutate {
        id => "ABC"
      }
    }

Call the filter flush method at regular interval. Optional.

If this filter is successful, remove arbitrary fields from this event. Fields names can be dynamic and include parts of the event using the %{field} Example:

    filter {
      mutate {
        remove_field => [ "foo_%{somefield}" ]
      }
    }

    # You can also remove multiple fields at once:
    filter {
      mutate {
        remove_field => [ "foo_%{somefield}", "my_extraneous_field" ]
      }
    }

If the event has field "somefield" == "hello" this filter, on success, would remove the field with name foo_hello if it is present. The second example would remove an additional, non-dynamic field.

If this filter is successful, remove arbitrary tags from the event. Tags can be dynamic and include parts of the event using the %{field} syntax.

Example:

    filter {
      mutate {
        remove_tag => [ "foo_%{somefield}" ]
      }
    }

    # You can also remove multiple tags at once:
    filter {
      mutate {
        remove_tag => [ "foo_%{somefield}", "sad_unwanted_tag"]
      }
    }

If the event has field "somefield" == "hello" this filter, on success, would remove the tag foo_hello if it is present. The second example would remove a sad, unwanted tag as well.