Can you change environment variables with putenv() in the Craft Cloud serverless app container?

[jamesmacwhite]

I have a potential use case for using an environment variable that triggers specific logic and would be conditional based on a specific scenario that would go beyond the current deployment model, where you need to amend the environment variable in Craft Console on an environment and do a manual deployment.

If a plugin/module called putenv() in its init() class which is in the applicaiton bootstrap would the environment variable change work under serverless in the container image, without changing the main environment variables under Craft Console?

[timkelty]

putenv should work as expected, and have no affect under the variables defined for you environment in Craft Console.

That said, without knowing more about your use-case, it feels a bit odd to me…
At that point it seems like you're conditionally assigning some global config…why bother making it an env if it isn't really one?

[jamesmacwhite]

Bit of interesting one I know, but basically the need is because of environment variables being usable at the Craft App/Config level i.e. initialised and available reliably, rather than a field setting on a global or preloaded single, which isn't the case if you wanted to do that at say the App/Config.

The putenv() use is to basically set an environment variable but only when a specific condition is met. It can of course be defined through the normal env var pattern, but it is more for a specific date condition. Maybe the 31st Oct.... For a bit of Halloween fun.

[jamesmacwhite]

All becomes clear on the 31st October, Happy Halloween!

Our Halloween surprise: https://www.nottinghamcollege.ac.uk/student-life/campuses

With the date condition, I am using putenv to send the value of the environment variable and then in the app config setting a custom config setting based on that putenv value to use in places to conditionally logic a few things:

Translations (loading a specific en translation for changing our campuse names) when this is active.
Body classes on specific entries for condition styling targetting.
A service that modifies all image assets for our campuses based on the putenv value

Way overengineered for what it is, but a bit of Halloween fun!

[andrewfairlie]

Love it

[timkelty]

Fun! ♥️

Not sure if it is coincidental or engineered, but my favorite part is the static cache is sync'd to expire after Halloween:
cdn-cache-control: public,max-age=86392,stale-while-revalidate=3600

[jamesmacwhite]

Fun! ♥️

Not sure if it is coincidental or engineered, but my favorite part is the static cache is sync'd to expire after Halloween: cdn-cache-control: public,max-age=86392,stale-while-revalidate=3600

Completely coincidental, but that's hilarious! Ha ha. Maybe becuase the service was triggered at 2025-10-31 00:00 it just so happens to be 24 hours by default from the last element save update.