firestire_client_init.go

func NewFirestoreBinManager(opts *FirestoreBinManagerOpts) (*FirestoreBinManager, error) {
	ctx := context.Background()
	var options []option.ClientOption
	if opts.CredsFile != "" {    
		options = append(options, option.WithCredentialsFile(opts.CredsFile))
	}
  // credentials file option is optional, by default it will use GOOGLE_APPLICATION_CREDENTIALS
  // environment variable, this is a default method to connect to Google services
	client, err := firestore.NewClient(ctx, opts.ProjectID, options...) 
	if err != nil {
		return nil, err
	}
	return &FirestoreBinManager{
		binsCollection: opts.BinsCollection,  // our bins collection name
		reqsCollection: opts.ReqsCollection,  // our requests collection name
		client:         client,
		pubsub:         opts.Pubsub,
		logger:         opts.Logger,
	}, nil
}