Dump a Cloud SQL MySQL instance from an external server

Question

I followed this guide to configure an external instance replicating a Cloud SQL MySQL instance. Unfortunately something went wrong or I'm misinterpreting the concept of "external replica" in gcloud; maybe external means another VM in the gcloud platform, not a VM hosted by another cloud provider?
For a description of the error and the possible cause please check this other post.
Now I'm trying to narrow down the issue and finally I noticed that when running mysqldump from the external VM with the --master-data option it hangs forever.
E.g. the following works:

/usr/bin/mysqldump --single-transaction -h x.x.x.x -u root -p db_name table_name

while this hangs:

/usr/bin/mysqldump --single-transaction --master-data -h x.x.x.x -u root -p db_name table_name

Has anyone managed to successfully configure an external slave replicating from a Cloud SQL MySQL instance?

Answer 1

According to the official documentation :

Replication in Cloud SQL

External read replicas External read replicas are external MySQL instances that replicate from a Cloud SQL primary instance. For example, a MySQL instance running on Compute Engine is considered an external instance.

External read replicas have the following restrictions:

Replicating to a MySQL instance hosted by another cloud platform might not be possible; check the documentation from the other provider

Therefore is important to check the documentation of the other cloud provider.