code: func NewDNSProvider() (*DNSProvider, error) {
  	config := NewDefaultConfig()
  	config.SubscriptionID = env.GetOrFile("AZURE_SUBSCRIPTION_ID")
  	config.ResourceGroup = env.GetOrFile("AZURE_RESOURCE_GROUP")
  
  	return NewDNSProviderConfig(config)
  }
docs: // NewDNSProvider returns a DNSProvider instance configured for azure.
  // Credentials can be passed in the environment variables:
  // AZURE_CLIENT_ID, AZURE_CLIENT_SECRET, AZURE_SUBSCRIPTION_ID, AZURE_TENANT_ID, AZURE_RESOURCE_GROUP
  // If the credentials are _not_ set via the environment,
  // then it will attempt to get a bearer token via the instance metadata service.
  // see: https://github.com/Azure/go-autorest/blob/v10.14.0/autorest/azure/auth/auth.go#L38-L42