Support provisioning of read replica

[manuelnucci]

I'd be really helpful to be able to create a read replica alongside main server.

According to the docs, it's now possible by setting create_mode = "Replica".

I don't fully understand how creation_source_server_id is expected to work, maybe using the same id the resource has as output?

I hope this feature can be implemented soon.

Keep up the good work! Cheers!

[yupwei68]

Hi, thanks for opening this issue.
We may enhance this feature in the future. But currently I could not give a plan for it.
You're welcome to contribute to this module by raising a PR as well.
If you want to open a PR, please add this feature into the test in test/fixture to integrate the test CI and add this feature in example in README.