Rationale: Provides a few different options for configuring Google Cloud credetials.
Usage:
let gc_config = require('google-cloud-json-environment-credential')
gc_config.configure()
OR
gc_config.configure(<file path of local credentials.json>)
Flow
If the environment variable GOOGLE_APPLICATION_CREDENTIALS is set this script returns without doing anything.
If the environment variable GOOGLE_APPLICATION_CREDENTIALS_JSON is set, this script will save the JSON to a local temp file and set GOOGLE_APPLICATION_CREDENTIALS with that file's path.
If the optional credentialsJsonFile parameter is passed to this script it will set GOOGLE_APPLICATION_CREDENTIALS to that value.
If none of the above apply GOOGLE_APPLICATION_CREDENTIALS will be set to credentials.json and hope for the best.