:plugin: fingerprint
:type: filter

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:version: %VERSION%
:release_date: %RELEASE_DATE%
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:include_path: ../../../../logstash/docs/include
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[id="plugins-{type}s-{plugin}"]

=== Fingerprint filter plugin

include::{include_path}/plugin_header.asciidoc[]

==== Description

Create consistent hashes (fingerprints) of one or more fields and store
the result in a new field.

This can e.g. be used to create consistent document ids when inserting
events into Elasticsearch, allowing events in Logstash to cause existing
documents to be updated rather than new documents to be created.

NOTE: When the `target` option is set to `UUID` the result won't be
a consistent hash but a random
https://en.wikipedia.org/wiki/Universally_unique_identifier[UUID].
To generate UUIDs, prefer the {logstash-ref}/plugins-filters-uuid.html[uuid filter].

[id="plugins-{type}s-{plugin}-options"]
==== Fingerprint Filter Configuration Options

This plugin supports the following configuration options plus the <<plugins-{type}s-{plugin}-common-options>> described later.

[cols="<,<,<",options="header",]
|=======================================================================
|Setting |Input type|Required
| <<plugins-{type}s-{plugin}-base64encode>> |<<boolean,boolean>>|No
| <<plugins-{type}s-{plugin}-concatenate_sources>> |<<boolean,boolean>>|No
| <<plugins-{type}s-{plugin}-concatenate_all_fields>> |<<boolean,boolean>>|No
| <<plugins-{type}s-{plugin}-key>> |<<string,string>>|No
| <<plugins-{type}s-{plugin}-method>> |<<string,string>>, one of `["SHA1", "SHA256", "SHA384", "SHA512", "MD5", "MURMUR3", "IPV4_NETWORK", "UUID", "PUNCTUATION"]`|Yes
| <<plugins-{type}s-{plugin}-source>> |<<array,array>>|No
| <<plugins-{type}s-{plugin}-target>> |<<string,string>>|No
|=======================================================================

Also see <<plugins-{type}s-{plugin}-common-options>> for a list of options supported by all
filter plugins.

&nbsp;

[id="plugins-{type}s-{plugin}-base64encode"]
===== `base64encode` 

  * Value type is <<boolean,boolean>>
  * Default value is `false`

When set to `true`, the `SHA1`, `SHA256`, `SHA384`, `SHA512` and `MD5` fingerprint methods will produce
base64 encoded rather than hex encoded strings.

[id="plugins-{type}s-{plugin}-concatenate_sources"]
===== `concatenate_sources` 

  * Value type is <<boolean,boolean>>
  * Default value is `false`

When set to `true` and `method` isn't `UUID` or `PUNCTUATION`, the
plugin concatenates the names and values of all fields given in the
`source` option into one string (like the old checksum filter) before
doing the fingerprint computation. If `false` and multiple source
fields are given, the target field will be an array with fingerprints
of the source fields given.

[id="plugins-{type}s-{plugin}-concatenate_all_fields"]
===== `concatenate_all_fields` 

  * Value type is <<boolean,boolean>>
  * Default value is `false`

When set to `true` and `method` isn't `UUID` or `PUNCTUATION`, the
plugin concatenates the names and values of all fields of the event 
into one string (like the old checksum filter) before doing the 
fingerprint computation. If `false` and at least one source field is 
given, the target field will be an array with fingerprints of the 
source fields given.

[id="plugins-{type}s-{plugin}-key"]
===== `key` 

  * Value type is <<string,string>>
  * There is no default value for this setting.

When used with the `IPV4_NETWORK` method fill in the subnet prefix length.
With other methods, optionally fill in the HMAC key.

[id="plugins-{type}s-{plugin}-method"]
===== `method` 

  * This is a required setting.
  * Value can be any of: `SHA1`, `SHA256`, `SHA384`, `SHA512`, `MD5`, `MURMUR3`, `IPV4_NETWORK`, `UUID`, `PUNCTUATION`
  * Default value is `"SHA1"`

The fingerprint method to use.

If set to `SHA1`, `SHA256`, `SHA384`, `SHA512`, or `MD5` and a key is set,
the cryptographic hash function with the same name will be used to generate
the fingerprint. When a key set, the keyed-hash (HMAC) digest function will
be used.

If set to `MURMUR3` the non-cryptographic MurmurHash function will be used.

If set to `IPV4_NETWORK` the input data needs to be a IPv4 address and
the hash value will be the masked-out address using the number of bits
specified in the `key` option. For example, with "1.2.3.4" as the input
and `key` set to 16, the hash becomes "1.2.0.0".

If set to `PUNCTUATION`, all non-punctuation characters will be removed
from the input string.

If set to `UUID`, a
https://en.wikipedia.org/wiki/Universally_unique_identifier[UUID] will
be generated. The result will be random and thus not a consistent hash.

[id="plugins-{type}s-{plugin}-source"]
===== `source` 

  * Value type is <<array,array>>
  * Default value is `"message"`

The name(s) of the source field(s) whose contents will be used
to create the fingerprint. If an array is given, see the
`concatenate_sources` option.

[id="plugins-{type}s-{plugin}-target"]
===== `target` 

  * Value type is <<string,string>>
  * Default value is `"fingerprint"`

The name of the field where the generated fingerprint will be stored.
Any current contents of that field will be overwritten.



[id="plugins-{type}s-{plugin}-common-options"]
include::{include_path}/{type}.asciidoc[]