Pass ENV variable from OS into NodeRed (from Docker...)

[Jéan Roux]

Hi, with Docker - in the compose yaml file, one can set environment variables (ENV) for the node that starts up. 

I see several discussions previously on the need / request for the ability to pass O/S ENV variables into flows, but not sure from reading them, that this is possible, also found no flows that could offer this capability.

In my use case, I fire up instances of NR in Docker - as front end client to backend processes, each client app I currently config with a config.cfg file, where I hold a json key pair sting, which then configures the front-end interface, using NR ui for that.

Would be cool if I rather - in the yaml compose file, pass this json string into the OS as an ENV, and then - NR as it starts up, pick up the ENV variable from the OS, and configures the front end client, one less thing that can go wrong.

Is it possible to read an OS ENV variable from within NR ?

[Ivan Tarozzi]

Hi Jéan,

you can solve using a javascript function node with this content:

  msg.payload = context.global.process.env.JAVA_HOME

  return msg;

But you need to modify your ~/.node-red/settings.js in this section, adding process module:

 functionGlobalContext: {
               os:require('os'), 
               process:process 

   },

[Jéan Roux]

I will try it, thank you!

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[Nathanaël Lécaudé]

In most configuration fields you can also use this notation to access environment variables:

$(MY_VARIABLE)

[Ivan Tarozzi]

Il giorno giovedì 27 luglio 2017 16:24:56 UTC+2, Nathanaël Lécaudé ha scritto:

In most configuration fields you can also use this notation to access environment variables:

$(MY_VARIABLE)

 

Wonderful! I didn't know that way. It works without modification to settings.js file!  Thank you very much.

[Jéan Roux]

Thank you Ivan, this works.