Different Types of Patches

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When to use each patch type

• JSON 6902 patches are RFC 6902 JSON Patch documents (arrays of operations). They give fine-grained control (add, remove, replace, test, move) and are ideal when you need to target a precise JSON path.
• Strategic merge patches are Kubernetes-aware YAML snippets that merge with the existing object structure. They are easier to read and write for straightforward configuration changes (e.g., changing replica count, adding labels).

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JSON 6902 patch

patchesJson6902:
- target:
    group: apps
    version: v1
    kind: Deployment
    name: api-deployment
  patch: |-
    [
      { "op": "replace", "path": "/spec/replicas", "value": 5 }
    ]

patchesJson6902:
- target:
    group: apps
    version: v1
    kind: Deployment
    name: api-deployment
  path: replica-patch.json

[
  { "op": "replace", "path": "/spec/replicas", "value": 5 }
]

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Strategic merge patch

patchesStrategicMerge:
- |-
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: api-deployment
  spec:
    replicas: 5

patchesStrategicMerge:
- replica-strategic-patch.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: api-deployment
spec:
  replicas: 5

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Quick comparison

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Best practices

• Keep kustomization.yaml readable: prefer external files when patches are long or numerous.
• Use JSON 6902 for exact JSON path operations or scripted automation.
• Use strategic merge patches when changing structural fields that merge naturally (e.g., spec, metadata).
• Validate JSON 6902 patch arrays for correct syntax and valid JSON (tools or CI checks can help).

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Summary

• Both JSON 6902 and Strategic Merge patches can be provided inline or referenced as external files from kustomization.yaml.
• Inline patches are convenient for small edits; external files are better for organization and maintainability when dealing with many patches.
• Pick the patch style that best matches the change semantics and team readability preferences.

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Links and references

• RFC 6902 — JSON Patch
• Kustomize — patches documentation: https://kubectl.docs.kubernetes.io/guides/introduction/kustomize/ (or check your Kustomize / kubectl docs for your version)
• Kubernetes API concepts: https://kubernetes.io/docs/concepts/overview/working-with-objects/kubernetes-objects/