My response based on limited experience with the Spanner Export tool.
I have not seen a way to do this. There is no option in the GCP console, though that does not mean it cannot be done.
There is no built-in scheduling capability. Perhaps this can be done via Google's managed Airflow service, Cloud Composer (https://console.cloud.google.com/composer)? I have yet to try this, but it is next step as I have similar needs.
I've made this request to Google several times. I have yet to get a response. My best recommendation is to read the change logs when updating the gcloud
CLI.
Finally-- there is an outstanding issue with the Export tool that causes it to fail if you export a table with 0 rows. I have filed a case with Google (Case #16454353) and they confirmed this issue. Specifically:
After running into a similar error message during my reproduction of
the issue, I drilled down into the error message and discovered that
there is something odd with the file path for the Cloud Storage folder
[1]. There seems to be an issue with the Java File class viewing
‘gs://’ as having a redundant ‘/’ and that causes the ‘No such file or
directory’ error message.
Fortunately for us, there is an ongoing internal investigation on this
issue, and it seems like there is a fix being worked on. I have
indicated your interest in a fix as well, however, I do not have any
ETAs or guarantees of when a working fix will be rolled out.