code: func GetOrFile(envVar string) string {
  	envVarValue := os.Getenv(envVar)
  	if envVarValue != "" {
  		return envVarValue
  	}
  
  	fileVar := envVar + "_FILE"
  	fileVarValue := os.Getenv(fileVar)
  	if fileVarValue == "" {
  		return envVarValue
  	}
  
  	fileContents, err := ioutil.ReadFile(fileVarValue)
  	if err != nil {
  		log.Printf("Failed to read the file %s (defined by env var %s): %s", fileVarValue, fileVar, err)
  		return ""
  	}
  
  	return string(fileContents)
  }
docs: // GetOrFile Attempts to resolve 'key' as an environment variable.
  // Failing that, it will check to see if '<key>_FILE' exists.
  // If so, it will attempt to read from the referenced file to populate a value.