my goal is set primary and secondary zone in Google Cloud SQL instance using terraform. It can be easily done using UI, but I would like to achieve this using terraform.
In the terraform documentation google_sql_database_instance there is option to set primary zone using settings.location_preference.location which allows to set Primary Zone, but I am not able to configure Secondary Zone or find any examples.
I've tried to use list type but terraform is expecting only 1 string for location_preference.location. I also tried some kind of workaround to use follow_gae_application but as I don't have Google App Engine application it also resulted in error.
Any ideas if this is possible or there are any workarounds?
EDIT:
I already set availability_type to Regional. When creating Cloud SQL instance, it creates Primary zone with zone mentioned in preferred_location, but secondary zone is set randomly (sometimes is -a, sometimes is -b or -d.
Regarding settings.backup_configuration.location it's where backup of Cloud SQL instance will be created. Expected value is 'region' so (eu, us or asia).