How to set a variable as a file without output?

Is there a way to load a variable into you job as a file (get)? I have a vault secure JSON key, but I have to set it as a file for the tool to use it in a run script.

I can do a simple cat or echo or tee to write it to the file, but the output gets displayed, which since it’s a secure key is not good. Is there a resource type I could use for this? Or has someone figured this out before?

If you’re using Concourse 6+ the experimental load_var step might do what you’re looking for.