How do I prevent a folder from being removed when running nexus build?

[uncvrd]

Quick question. I have a folder inside my working directory that stores a .pem file to sign a token. This is stored in /api/keys/apple/key.pem. I reference this file in a method like so:

const keyDirectory = path.join(__dirname, '../keys/apple')
const cert_private = fs.readFileSync(keyDirectory + '/AuthKey.pem')

const newToken = await jwt.sign({}, cert_private, jwtOptions)

This works great in development, but when I run nexus build the keys folder is not added to the output. Which I assume means it was tree-shaken out of the build since I'm not using an import statement to load the .pem. Is there a way to force a folder to be added to my build folder when running nexus build?

EDIT:

Is the preferred method to define a postbuild script to move the file over?