containerd 2.3 becomes the project’s first annual LTS release

The containerd project released version 2.3.0 on April 30 and designated it the first annual Long Term Stable release under a new schedule. The official release notes say minor releases will align roughly with Kubernetes’ four-month cadence, while annual LTS lines receive at least two years of planned support.

Runtime interfaces keep expanding

Version 2.3 adds transfer types for copying container filesystems and extends the sandbox API with a specification field. CRI changes include wiring pod-sandbox resource updates to the sandbox API, allowing user namespaces with host networking, and applying per-layer labels when unpacking images for a specific runtime.

Image work adds media-type and platform-feature handling for zstd-wrapped EROFS layers. The EROFS snapshotter gains dm-verity support and uses the fsmount API to avoid a page-size limit. Node Resource Interface updates expose more container configuration to plugins, including user and group IDs, resource limits, devices, sysctls, and lifecycle events.

LTS changes the upgrade planning question

The project says direct upgrades between sequential LTS releases, using 1.7 to 2.3 as its example, will be tested and supported. That gives operators a clearer long-lived path, but it does not remove integration testing with kubelet, CRI plugins, snapshotters, and low-level runtimes.

Before adopting 2.3, platform teams should clone a representative node image, validate configuration migration, pull and unpack their common image formats, and exercise pod creation, update, restart, and teardown. Custom NRI plugins deserve contract tests because the wire protocol and available adjustment data have grown. The useful outcome is an upgrade matrix for each node class, with explicit rollback images, rather than relying on the LTS label as a substitute for environment testing.