☂ Migrate remaining configuration files to YAML format

[bneradt]

Summary

This umbrella issue tracks the migration of all remaining .config configuration files to YAML format. ATS has been progressively moving to YAML for configuration files to provide a more structured, readable, and maintainable configuration experience.

Background

Several configuration files have already been converted to YAML:

• ✅ ip_allow.yaml
• ✅ jsonrpc.yaml
• ✅ logging.yaml
• ✅ records.yaml
• ✅ sni.yaml
• ✅ strategies.yaml

Remaining Configuration Files

The following files still use the legacy .config format and should be migrated to YAML:

• [ ] cache.config → cache.yaml (see #7701)
• [ ] hosting.config → hosting.yaml
• [ ] parent.config → parent.yaml
• [ ] plugin.config → plugin.yaml
• [ ] remap.config → remap.yaml @serrislew (see #5590)
• [ ] socks.config → socks.yaml
• [ ] splitdns.config → splitdns.yaml
• [ ] ssl_multicert.config → ssl_multicert.yaml @bneradt (see #12755)
• [ ] storage.config → storage.yaml
• [ ] volume.config → volume.yaml (see #10766)

Related Issues

• #5590 - ☂ Migration to remap.yaml
• #7701 - When rewriting cache.config in YAML, make it not additive
• #10766 - Change volume.config to volume.yaml
• #5363 - ☂ Remove various _filename records.config variables

Migration Guidelines

For each configuration file migration:

1. Design a YAML schema with a consistent top-level namespace (per #5245)
2. Implement the YAML parser alongside the existing parser
3. Provide a migration script or tool for users
4. Update documentation
5. Deprecate the old format with appropriate warnings
6. Remove the old format in a future major release

Note: these conversions should be done on the 11-Dev branch since these conversions will not be done in the 10.x release series.