# Share Variables across multiple RPi

**URL:** <https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538>\
**Category:** General\
**Created:** [2 March 2019 21:29 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538 "2019-03-02T21:29:32Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![tsdasd](https://avatars.discourse-cdn.com/v4/letter/t/71e660/32.png) [@tsdasd](https://discourse.nodered.org/u/tsdasd)\
**Post date:** [2 March 2019 21:29 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/1 "2019-03-02T21:29:32Z")

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What would be your ideal approach to share global variables across multiple RPi's each with one node-red instance?

Would you take the approach of a MySQL database where you could write / read the variables?

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**Author:** ![cymplecy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/cymplecy/32/2773_2.png) [@cymplecy](https://discourse.nodered.org/u/cymplecy)\
**Post date:** [2 March 2019 21:49 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/2 "2019-03-02T21:49:03Z")

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I'd just use MQTT and persistent storage on each Pi

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [2 March 2019 21:55 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/3 "2019-03-02T21:55:55Z")

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+1 for MQTT.

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**Author:** ![zenofmud](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/zenofmud/32/316_2.png) [@zenofmud](https://discourse.nodered.org/u/zenofmud)\
**Post date:** [3 March 2019 11:25 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/4 "2019-03-03T11:25:54Z")

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+2 for MQTT

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**Author:** ![ghayne](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ghayne/32/39_2.png) [@ghayne](https://discourse.nodered.org/u/ghayne)\
**Post date:** [3 March 2019 11:28 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/5 "2019-03-03T11:28:23Z")

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+3 for MQTT.

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**Author:** ![Robbo](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/robbo/32/4491_2.png) [@Robbo](https://discourse.nodered.org/u/Robbo)\
**Post date:** [3 March 2019 11:43 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/6 "2019-03-03T11:43:42Z")

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If your unfamiliar with MQTT then this guide seems to be a good read;  
[https://www.hivemq.com/blog/mqtt-essentials-part-1-introducing-mqtt/](https://www.hivemq.com/blog/mqtt-essentials-part-1-introducing-mqtt/)

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**Author:** ![tsdasd](https://avatars.discourse-cdn.com/v4/letter/t/71e660/32.png) [@tsdasd](https://discourse.nodered.org/u/tsdasd)\
**Post date:** [3 March 2019 20:51 UTC](https://discourse.nodered.org/t/share-variables-across-multiple-rpi/8538/7 "2019-03-03T20:51:50Z")

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thanks i will have a look at the guide and will be using mqtt