I have a Google Firebase app with a Cloud Functions back-end. I'm using the node.js 10 runtime which is Ubuntu 18.04. Users can upload files to Google Cloud Storage, and that triggers a GCF function.
What I'd like that function to do is copy that file to Google Cloud Filestore (that's File with an L), Google's new NFS-mountable file server. They say the usual way to do that is from the command line with gsutil rsync or gcloud compute scp.
My question is: are either or both of those commands available on GCF nodes? Or is there another way? (It would be awesome if I could just mount the Filestore share on the GCF instance, but I'm guessing that's nontrivial.)
Using NFS based storage is not a good idea in this environment. NFS works by providing a mountable file system, something that will not work in Cloud Functions environment as the file system is read only with the exception of /tmp folder.
You should consider using cloud native storage systems like GCS for which the Application Default Credentials are already setup. See the list of supported services here.