Create a way to provide environment variables

[greatvovan]

As Scala lacks methods for setting environment variables, simulation of them for code that consumes environment is complicated.

I got away with build settings like that:

fork in run := true

envVars in run := Map(
  "MY_VAR" -> "MY VALUE"
)

Example:

println(sys.env("MY_VAR"))
Thread.sleep(5000)

The problems with that approach are:

• the console output of the program is displayed differently than in normal mode (sbt prefix);
• after program termination the bottom panel switches to the program output (which stays empty forever), effectively hiding the real output.

I suggest to add a tab where the user could set environment variables in an intuitive way.

[arnavsharma990]

It would be really useful if Scastie had an “Env Vars” tab where users can define key/value pairs before running code. These could be passed to the backend runner (e.g., via ProcessBuilder.environment()) so they’re available through sys.env("KEY") during execution. The variables should only exist for that single run to keep things secure. This would let people test environment-dependent code without hard-coding values, making Scastie feel closer to real-world setups.

Please assign this issue to me so I can work on it.

[warcholjakub]

Just checking in - are you still working on this feature? If not, I’d be happy to pick it up and give it a try. @arnavsharma990