Containerd API 1.12.0-rc.1 introduces deprecations requiring action

The containerd project has released API version 1.12.0-rc.1, aligning with containerd 2.4. This pre-release includes notable updates such as the addition of the UpdateSandbox RPC for sandbox controller updates and enhancements to checkpointing with runc. However, it also introduces deprecations that operators must address before upgrading. Specifically, the containerd.io/runtime-allow-mounts shim annotation is deprecated in favor of the MountCapabilities bootstrap extension, and the task API address and version fields in runc options are deprecated, now moved to CreateTaskRequest.

Operators should carefully review their configurations and workflows that rely on the deprecated shim annotation and runc options. Any automation or tooling that references these fields may break after upgrading. Testing the pre-release binaries in a staging environment is recommended to identify potential compatibility issues. This pattern of deprecating features in favor of newer mechanisms reflects the project's ongoing efforts to streamline functionality and improve extensibility, as noted in the release notes.