How to pass variable to Terrraform ?

[KiteVision]

Hi everyone and thanks a lot to SemaphoreUI's team for your project !
Can someone please explain me how to pass a variable to Terraform using the "extra args" windows ?
I tried something like : [ "-var="ssh_private_key=$SSH-PRIVATE-KEY""] where SSH-PRIVATE-KEY is a secret value I defined in the project environment, and ssh-private-key the variable name in Terraform.... but it doesnt work

[KiteVision]

Bug ? Some more information for whom it may be useful : It looks like a bug because variables are indeed taken into account by Terraform "plan" phase when defined in the environnement section, nevertheless they are not know any more when starting the "apply" phase.
I have tested that defining a ssh_private_key variable : the "terraform plan" phase runs well and ask a confirmation to start the "terraform apply" phase which then raise an exception ("ssh_private_key not defined" in my case)