如何通过未存储在golang的GAE或GCE中的应用程序使用Google Cloud DataStore API?

In GCP, I got the jsonKeyFile.json, and want to use it in code. However it cannot run in the way I want. My application is not hosted in GAE or GCE.

In my code, I write like this.

client, err := datastore.NewClient(ctx context.Context, projectID string, option.WithAccountServiceFile("path/to/jsonKeyFile.json"))

When the path name is absolute path, this application can run safely, but when it is just the file name, this cannot run. When I use option.WithAccountsServiceFile(), should I write the path name in absolutely?

Or I take the wrong way to authorize and authenticate to use GCP's API?