Does Google Cloud Spanner support stored procedures?
I've had a quick search through the docs at https://cloud.google.com/spanner/docs/overview but couldn't find any reference to stored procs / user defined routines anywhere.
It would be good to find out for certain if they are/aren't supported.
No, it does not support stored procedures. You could use something like App Engine for small server side scripts or call Dataflow jobs for larger ones.