# Clarification on Environment variables

**URL:** <https://community.fly.io/t/clarification-on-environment-variables/6309>\
**Category:** General\
**Created:** [August 9, 2022, 12:47am UTC](https://community.fly.io/t/clarification-on-environment-variables/6309 "2022-08-09T00:47:09Z")\
**Posts on this page:** 1\
**Showing post:** 17

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**Author:** ![ignoramous](https://avatars.discourse-cdn.com/v4/letter/i/a9adbd/32.png) [@ignoramous](https://community.fly.io/u/ignoramous)\
**Post date:** [December 20, 2022, 6:03pm UTC](https://community.fly.io/t/clarification-on-environment-variables/6309/17 "2022-12-20T18:03:26Z")

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> [@bodgerbarnett](#):
>
> Am I to assume from the solution here that I need to put the actual recaptcha key into the build args in the fly.toml file to make this work? If so, how do I keep the secret, errrrr, secret?!

With build-time secrets? [Best practice for build-time secrets? - #2 by fideloper-fly](https://community.fly.io/t/best-practice-for-build-time-secrets/7519/2)

Store these secrets in your OS’ keychain / keystore, or your CI’s vault, depending on where you’re building the docker image.

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