kubernetes/kubernetes

Decoding should not clear apiVersion/kind

Open

#80,609 opened on Jul 25, 2019

View on GitHub
 (21 comments) (55 reactions) (0 assignees)Go (43,066 forks)batch import
help wantedkind/featurelifecycle/frozensig/api-machinerytriage/accepted

Repository metrics

Stars
 (122,268 stars)
PR merge metrics
 (Avg merge 28d 17h) (343 merged PRs in 30d)

Description

What would you like to be added: When using a typed client, decoding to a versioned struct (not an internal API type), the apiVersion/kind information returned from the server should not be dropped.

Why is this needed: The GroupVersionKind() method included in the ObjectKind interface is largely useless when dealing with arbitrary runtime.Object instances, since typed instances drop this information here:

https://github.com/kubernetes/kubernetes/blob/69a34f6a6f67de47cb9b72b6ac98e089d301beb3/staging/src/k8s.io/apimachinery/pkg/runtime/helper.go#L245-L259

This is the decoder used when a client requests a decoder that does not do conversion:

https://github.com/kubernetes/kubernetes/blob/69a34f6a6f67de47cb9b72b6ac98e089d301beb3/staging/src/k8s.io/apimachinery/pkg/runtime/serializer/codec_factory.go#L175-L179

I could see clearing group/version/kind information when converting to an internal version, but I don't see the benefit of stripping it on decode if we're only dealing with a versioned struct.

/sig api-machinery /cc @smarterclayton

Note that https://github.com/kubernetes/kubernetes/issues/3030 still needs to be resolved before apiVersion/kind could be depended on for individual objects for all API responses, but this would at least solve the issue with an update of an object clearing the apiVersion/kind in an update response (xref https://github.com/kubernetes-sigs/controller-runtime/issues/526)

Contributor guide

Research direction
Investigate the decode function in staging/src/k8s.io/apimachinery/pkg/runtime/helper.go line 245-259 and the codec factory.go line 175-179. Understand why apiVersion/kind is cleared and consider modifying the decode path to preserve it for versioned structs. Coordinate with the sig api machinery community reference in the issue.
Tech stack
go
Domain
api
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Go
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
55