# Need to generate UUID in painless script

**URL:** <https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318>\
**Category:** Elasticsearch\
**Created:** [January 23, 2019, 12:29am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318 "2019-01-23T00:29:18Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Oliver\_Henlich](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/oliver_henlich/32/133516_2.png) [@Oliver\_Henlich](https://discuss.elastic.co/u/Oliver_Henlich)\
**Post date:** [January 23, 2019, 12:29am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/1 "2019-01-23T00:29:18Z")

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Hi,

I am trying to use the reindex api to create a copy of a set of documents. One of the fields (productId) of the document is a UUID. I need the copied documents to have new UUIDs for the productId field.

Please note, simply using the elastic search \_id field is not an option as services using these documents depend on this field being a valid UUID.

According to [1] and [2] the method java.util.UUID.randomUUID() is not whitelisted for use in painless scripts.

Questions:

1. Why is randomUUID() considered an unsafe operation? Or is it just an oversight that it is not whitelisted?

2. What would be the process for whitelisting this method on our ES server? I have read [3] which describes supplying our own java policy file on jvm startup. The problem with this is that I don't really want to **overwrite** all the existing policies but only **add** to them. Is there a way to do this?

3. Will the approach described in [3] really work for painless whitelisting. Looking at the source, it seems there is a separate framework for whitelisting java classes for painless here [4].

Cheers  
Oliver

Details:

- Elastic Search: 6.4.2
- Deploying to kubernetes with helm ([https://github.com/elastic/helm-charts/tree/master/elasticsearch](https://github.com/elastic/helm-charts/tree/master/elasticsearch))

References:  
[1] - [Generate a UUID using randomuuid in painless](https://discuss.elastic.co/t/generate-a-uuid-using-randomuuid-in-painless/144354/3)  
[2] - [https://www.elastic.co/guide/en/elasticsearch/painless/6.4/painless-api-reference.html](https://www.elastic.co/guide/en/elasticsearch/painless/6.4/painless-api-reference.html)  
[3] - [https://www.elastic.co/guide/en/elasticsearch/reference/6.4/modules-scripting-security.html](https://www.elastic.co/guide/en/elasticsearch/reference/6.4/modules-scripting-security.html)  
[4] - [https://github.com/elastic/elasticsearch/blob/master/modules/lang-painless/src/main/resources/org/elasticsearch/painless/spi/java.util.txt](https://github.com/elastic/elasticsearch/blob/master/modules/lang-painless/src/main/resources/org/elasticsearch/painless/spi/java.util.txt)

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<div class="post-metadata">

**Author:** ![Oliver\_Henlich](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/oliver_henlich/32/133516_2.png) [@Oliver\_Henlich](https://discuss.elastic.co/u/Oliver_Henlich)\
**Post date:** [January 24, 2019, 11:05pm UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/2 "2019-01-24T23:05:32Z")

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Hi,

Since my post I've found the example plugin that seems to allow me to extend the whitelisting for painless scripts [5].

I've got it working but for queries only. I can't seem to find what to put for the **reindex** context here:

```
@Override
public Map<ScriptContext<?>, List<Whitelist>> getContextWhitelists() {
return Collections.singletonMap(SearchScript.CONTEXT, Collections.singletonList(WHITELIST));
}

```

I searched the whole ES code base for "new ScriptContext" to see if I could find one. There are many different contexts but nothing for "reindex".

Any advice on what to do here would be much appreciated.

@warkolm I saw you removed the security tag from this question. I used that tag because it seemed to me that the whole business of whitelisting methods that painless is allowed to use is a security issue.

[5] - [https://github.com/elastic/elasticsearch/tree/v6.5.4/plugins/examples/painless-whitelist](https://github.com/elastic/elasticsearch/tree/v6.5.4/plugins/examples/painless-whitelist)

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<div class="post-metadata">

**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\
**Post date:** [January 25, 2019, 1:04am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/3 "2019-01-25T01:04:42Z")

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The `Security` tag is specifically for posts relating to the stack functionality of the same name, ie [https://www.elastic.co/products/stack/security](https://www.elastic.co/products/stack/security)

It's not super clear though, so apologies for that confusion.

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<div class="post-metadata">

**Author:** ![Oliver\_Henlich](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/oliver_henlich/32/133516_2.png) [@Oliver\_Henlich](https://discuss.elastic.co/u/Oliver_Henlich)\
**Post date:** [January 25, 2019, 7:12am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/4 "2019-01-25T07:12:24Z")

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Thanks @warkolm.

Can you or someone from ES give me some quick pointers for the actual question? Or let me know if what I'm trying to achieve is currently impossible.

Cheers  
Oliver

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<div class="post-metadata">

**Author:** ![Oliver\_Henlich](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/oliver_henlich/32/133516_2.png) [@Oliver\_Henlich](https://discuss.elastic.co/u/Oliver_Henlich)\
**Post date:** [February 15, 2019, 12:32am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/5 "2019-02-15T00:32:09Z")

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Can somebody from ES help or give some pointers for this please.

I've asked the same question on stackoverflow too:

> <https://stackoverflow.com/questions/54682324/how-to-generate-a-uuid-in-elasticsearch-reindex-painless-script>

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [March 15, 2019, 12:32am UTC](https://discuss.elastic.co/t/need-to-generate-uuid-in-painless-script/165318/6 "2019-03-15T00:32:13Z")

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