Custom Resource Definitions: Let's Talk About Versioning and Releases
Talkat CNCF Maintainer Summit Europe 2025 · on Monday, 2025-03-31· at 14:30· Level 3 | ICC Capital Suite 14-16·
summary
CRD changes must be round-trippable to be safe so storage conversion doesn’t lose fields; examples show a width default and a singular→plural param change that remain safe until new values break round trips. Gateway API uses experimental vs standard channels with two install YAMLs, avoids conversion webhooks to reduce operator burden, and adds an X-prefixed API group for experimental objects so they can be removed safely. ValidatingAdmissionPolicy is being trialed to block experimental fields on standard installations, but implementations must import extra modules and handle migration.
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chapters (29)
- 0:00Introduction
- 0:45API changes in CRDs
- 1:06CRD deployments and versioning
- 2:08API vs schema vs storage version
- 3:13Round-triable changes
- 4:17Round-triability examples
- 6:46API changes and version bumps
- 7:27Feature flags in CRDs
- 8:51Gateway API channels
- 10:55Gateway API versioning pros/cons
- 13:02Experimental features risks
- 14:06CRD change types
- 16:13X- prefix in Gateway API
- 17:37X- prefix for CRDs?
- 18:19Future work and policies
- 20:05Q&A
- 22:55Core API versioning comparison
- 24:59Avoid conversion webhooks
- 26:25Standard vs experimental stability
- 27:49Experimental channel support
- 28:10CRD default installation
- 28:32Ecosystem compatibility
- 30:16Multiple CRD versions in etcd
- 31:41API version semantics
- 32:42Experimental on standard objects
- 34:07Field changes in experimental objects
- 35:52Security in CRD installation
- 36:14Tooling for experimental features
- 37:18Parent references in resources
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