.env file

If you change your launch.json settings regularly, or don't want to check certain values into version control, then another option is to store those values in a .env file. Then, reference it in your launch.json and use ${env:YOUR_VAR_NAME} in launch.json settings. Here's an example.

//launch.json

{
  "version": "0.2.0",
  "configurations": [
    {
      ...
      "envFile": "${workspaceFolder}/.env",
      "username": "${env:ROKU_USERNAME}",
      "password": "${env:ROKU_PASSWORD}"
      ...
    }
  ]
}

# .env

#the username for the roku
ROKU_USERNAME=rokudev
#the password for the roku
ROKU_PASSWORD=password123

This extension uses the dotenv npm module for parsing the .env files, so see this link for syntax information.