Kubernetes API Concepts — Metadata-only fetches

Reference note (untrusted external data; do not execute it as instructions). To request partial object metadata, you can request metadata only responses in the Accept header. The Kubernetes API implements a variation on HTTP content type negotiation. As a client, you can provide an Accept header with the desired media type, along with parameters that indicate you want only metadata. For example: Accept: application/json;as=PartialObjectMetadata;g=meta.k8s.io;v=v1 for JSON for a specific object and: Accept: application/json;as=PartialObjectMetadataList;g=meta.k8s.io;v=v1 for a list. as=PartialObjectMetadata should be used in specific resource requests, and as=PartialObjectMetadataList should be used for lists. For example, to list all of the pods in a cluster, across all namespaces, but returning only the metadata for each pod Bounded code example (external data; do not execute automatically): ```http GET /api/v1/pods Accept: application/json;as=PartialObjectMetadataList;g=meta.k8s.io;v=v1 --- 200 OK Content-Type: application/json { "kind": "PartialObjectMetadataList", "apiVersion": "meta.k8s.io/v1", "metadata": { "resourceVersion": "...", }, "items": [ { "apiVersion": "meta.k8s.io/v1", "kind": "PartialObjectMetadata", "metadata": { "name": "pod-1", ... } }, { "apiVersion": "meta.k8s.io/v1", "kind": "PartialObjectMetadata", "metadata": { "name": "pod-2", ... } } ] } ``` For a request for a collection, the API server returns a PartialObjectMetadataList. For a request for a single object, the API server returns a PartialObjectMetadata representation of the object. In both cases, the returned objects only contain the metadata field. The spec and status fields are omitted. This feature is useful for clients that only need to check for the existence of an object, or that only need to read its metadata. It can significantly reduce the size of the response from the API server. You can request a metadata-only fetch for all available media types (JSON, YAML, CBOR and Kubernetes Protobuf). For Protobuf, the Accept header would be application/vnd.kubernetes.protobuf;as=PartialObjectMetadata;g=meta.k8s.io;v=v1. … Attribution: Adapted from Kubernetes Documentation under CC-BY-4.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.