194 lines
3.7 KiB
Plaintext
194 lines
3.7 KiB
Plaintext
[[lang-javascript]]
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=== JavaScript Language Plugin
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The JavaScript language plugin enables the use of JavaScript in Elasticsearch
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scripts, via Mozilla's
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https://developer.mozilla.org/en-US/docs/Mozilla/Projects/Rhino[Rhino JavaScript] engine.
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[[lang-javascript-install]]
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[float]
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==== Installation
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This plugin can be installed using the plugin manager:
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[source,sh]
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----------------------------------------------------------------
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sudo bin/elasticsearch-plugin install lang-javascript
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----------------------------------------------------------------
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The plugin must be installed on every node in the cluster, and each node must
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be restarted after installation.
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[[lang-javascript-remove]]
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[float]
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==== Removal
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The plugin can be removed with the following command:
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[source,sh]
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----------------------------------------------------------------
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sudo bin/elasticsearch-plugin remove lang-javascript
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----------------------------------------------------------------
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The node must be stopped before removing the plugin.
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[[lang-javascript-usage]]
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==== Using JavaScript in Elasticsearch
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Once the plugin has been installed, JavaScript can be used at a scripting
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language by setting the `lang` parameter to `javascript`.
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Scripting is available in many APIs, but we will use an example with the
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`function_score` for demonstration purposes:
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[[lang-javascript-inline]]
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[float]
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=== Inline scripts
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WARNING: Enabling inline scripting on an unprotected Elasticsearch cluster is dangerous.
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See <<lang-javascript-file>> for a safer option.
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If you have enabled {ref}/modules-scripting-security.html#enable-dynamic-scripting[inline scripts],
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you can use JavaScript as follows:
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[source,json]
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----
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DELETE test
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PUT test/doc/1
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{
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"num": 1.0
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}
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PUT test/doc/2
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{
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"num": 2.0
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}
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GET test/_search
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{
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"query": {
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"function_score": {
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"script_score": {
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"script": {
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"inline": "doc[\"num\"].value * factor",
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"lang": "javascript",
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"params": {
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"factor": 2
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}
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}
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}
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}
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}
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}
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----
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// CONSOLE
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[[lang-javascript-stored]]
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[float]
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=== Stored scripts
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WARNING: Enabling stored scripts on an unprotected Elasticsearch cluster is dangerous.
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See <<lang-javascript-file>> for a safer option.
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If you have enabled {ref}/modules-scripting-security.html#enable-dynamic-scripting[stored scripts],
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you can use JavaScript as follows:
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[source,json]
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----
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DELETE test
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PUT test/doc/1
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{
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"num": 1.0
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}
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PUT test/doc/2
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{
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"num": 2.0
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}
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POST _scripts/javascript/my_script <1>
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{
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"script": "doc[\"num\"].value * factor"
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}
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GET test/_search
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{
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"query": {
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"function_score": {
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"script_score": {
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"script": {
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"id": "my_script", <2>
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"lang": "javascript",
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"params": {
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"factor": 2
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}
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}
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}
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}
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}
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}
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----
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// CONSOLE
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<1> We store the script under the id `my_script`.
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<2> The function score query retrieves the script with id `my_script`.
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[[lang-javascript-file]]
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[float]
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=== File scripts
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You can save your scripts to a file in the `config/scripts/` directory on
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every node. The `.javascript` file suffix identifies the script as containing
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JavaScript:
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First, save this file as `config/scripts/my_script.javascript` on every node
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in the cluster:
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[source,js]
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----
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doc["num"].value * factor
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----
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then use the script as follows:
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[source,json]
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----
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DELETE test
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PUT test/doc/1
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{
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"num": 1.0
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}
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PUT test/doc/2
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{
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"num": 2.0
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}
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GET test/_search
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{
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"query": {
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"function_score": {
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"script_score": {
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"script": {
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"file": "my_script", <1>
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"lang": "javascript",
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"params": {
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"factor": 2
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}
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}
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}
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}
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}
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}
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----
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// CONSOLE
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<1> The function score query retrieves the script with filename `my_script.javascript`.
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