[v2 CLI flag] --instances_metadata

[enocom]

This is a feature request for adding the --instances_metadata flag to v2.

Its description is:

If provided, it is treated as a path to a metadata value which
is polled for a comma-separated list of instances to connect to. For example,
to use the instance metadata value named 'cloud-sql-instances' you would
provide 'instance/attributes/cloud-sql-instances'. Not compatible with -fuse

If this is a useful flag that you'd like to see ported to v2, add a 👍 to this request.

[enocom]

This might be covered by #1045.

[enocom]

We're looking at adding support for dynamically configuring instance connection names from multiple sources (secret manager, pub/sub topics connected to a secret, and possibly instance metadata). Let's track that work over on #1045.