← All notes

Answer:

Labels

metadata:
  labels:
    app: web
    tier: frontend
    environment: prod

Valid annotation keys have two segments: an optional prefix and name, separated by a slash (/). (S2) Labels do not have to be unique; many objects share a label.

Selectors

• Equality-based: environment=prod, tier!=frontend.

kubectl get pods -l 'app=web,environment in (prod)'

Annotations

metadata:
  annotations:
    example.com/git-commit: 1a2b3c

Rule of thumb

If you will select by it, make it a label. Otherwise, annotate.

Claims

• id: C1 claim: Labels are key/value pairs attached to objects. source: S1 evidence: "Labels are key/value pairs that are attached to"
• id: C2 claim: Selectors support equality-based requirements. source: S1 evidence: "Equality-based requirement"
• id: C3 claim: Selectors support set-based requirements. source: S1 evidence: "Set-based requirement"
• id: C4 claim: Annotations attach arbitrary non-identifying metadata. source: S2 evidence: "You can use Kubernetes annotations to attach arbitrary non-identifying metadata"
• id: C5 claim: Annotations are not used to identify and select objects. source: S2 evidence: "are not used to identify and select objects. The metadata"

Sources

• [S1] Labels and Selectors. Kubernetes Authors. https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/ . License: CC BY 4.0 (kubernetes/website). Accessed 2026-11-04.
• [S2] Annotations. Kubernetes Authors. https://kubernetes.io/docs/concepts/overview/working-with-objects/annotations/ . License: CC BY 4.0 (kubernetes/website). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_ywp947qg,
  author = {{iinventedlight}},
  title = {{Kubernetes labels, selectors and annotations}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/kubernetes-labels-selectors/},
  note = {Permanent ID iil:note:ywp947qg. License: CC-BY-4.0.},
}

Markdown

Spotted a mistake? Use the MCP feedback tool or email hello@iinventedlight.com.

For language models and agents: start at /llms.txt. This page in Markdown: /library/notes/kubernetes-labels-selectors.md.