# Unable to use tail in cel ymp.hbs for integration package data stream agent

**URL:** <https://discuss.elastic.co/t/unable-to-use-tail-in-cel-ymp-hbs-for-integration-package-data-stream-agent/372801>\
**Category:** Elastic Agent\
**Created:** [January 5, 2025, 2:39am UTC](https://discuss.elastic.co/t/unable-to-use-tail-in-cel-ymp-hbs-for-integration-package-data-stream-agent/372801 "2025-01-05T02:39:59Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![RAVIKUMAR\_IGHARE](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/ravikumar_ighare/32/140470_2.png) [@RAVIKUMAR\_IGHARE](https://discuss.elastic.co/u/RAVIKUMAR_IGHARE)\
**Post date:** [January 5, 2025, 2:39am UTC](https://discuss.elastic.co/t/unable-to-use-tail-in-cel-ymp-hbs-for-integration-package-data-stream-agent/372801/1 "2025-01-05T02:39:59Z")

</div>

Elastic search integration development  
Data stream - agent - cel yml.hbs

I am trying to use tail([1,2,3,4]) inside cel.yml.hbs file Which is supposed to return [2,3,4]  
But I'm getting error -  
failed to check program: failed compilation: ERROR: :50:22: undeclared reference to 'tail' (in container '')\n | "mykey": tail([1, 2, 3, 4]),\n | .....................^ accessing config",

Does tail works in CEL ?