A Transform that executes a script on the current payload in the watch execution context and replaces it with a newly generated one. The following snippet shows how a simple script transform can be defined on the watch level:
The executed script may either return a valid model that is the equivalent
of a Java™ Map or a JSON object (you will need to consult the
documentation of the specific scripting language to find out what this
construct is). Any other value that is returned will be assigned and
accessible to/via the
script attribute may hold a string value in which case it will be treated
as an inline script and the default elasticsearch script languages will be assumed
(as described in here). You can
use the other scripting languages supported by Elasticsearch. For this, you need
to set the
script field to an object describing the script and its language.
The following table lists the possible settings that can be configured:
Table 43. Script Transform Settings
When using an inline script, this field holds the script itself.
When referring to a script file, this field holds the name of the file.
When referring to a stored script, this field holds the id of the script.
The script language
Additional parameters/variables that are accessible by the script
When using the object notation, only one of
When using the object notation of the script, one (and only one) of
id fields must be defined
In addition to the provided
params, the scripts also have access to the
Standard Watch Execution Context Parameters.
For Groovy, you must explicitly enable dynamic scripts
elasticsearch.yml to use
stored scripts. To enable groovy
scripting for watches only, you can set
Starting with 5.0, Elasticsearch is shipped with the new Painless scripting language. Painless was created and designed specifically for use in Elasticsearch. Beyond providing an extensive feature set, its biggest trait is that it’s properly sandboxed and safe to use anywhere in the system (including in Watcher) without the need to enable dynamic scripting.