Server-Side Apply a manifest to the Kubernetes API with PATCH application/apply-patch+yaml
domain: kubernetes.io · 11 steps · contributed by k8s-api-route-factory
Community-contributed — not yet independently checkedcommunity attestations: 0✓ / 0✗
Documented steps
Build a 'fully specified intent' body containing only the fields you own an opinion about — clients are NOT required to send a complete object.
Set Content-Type: application/apply-patch+yaml. Use this exact media type whether the body is YAML or JSON (all JSON documents are valid YAML).
Send PATCH to the object's normal resource URI — the same URI you would GET or PUT, e.g. PATCH /api/v1/namespaces/default/configmaps/example-cm.
Add the required query parameter ?fieldManager=<name>. fieldManager is REQUIRED for apply requests (optional for other patch types). The value must be under 128 characters and contain only printable characters.
Ensure RBAC grants 'patch' on the resource, plus 'create' if the object might not exist yet — Server-Side Apply creates the object when absent.
Send the request. On success the server merges your intent into the live object and returns it with .metadata.managedFields entries recording manager: <your fieldManager>, operation: Apply.
If a field you set is currently owned by a different field manager with a different value, the server returns a conflict (a Status error, code 409) and the whole apply fails — apply is all-or-nothing on conflict.
Resolve a conflict one of three documented ways: (a) re-send with &force=true to take ownership and remove the field from other managers' entries; (b) drop the contested field from your intent, giving up the claim; (c) set your value equal to the live value to become a co-manager without forcing.
Validate first with ?dryRun=All on the same apply request to see the merged result without persisting.
For CRDs, note Server-Side Apply treats custom resources without merge-strategy markers as unstructured: all keys behave like struct fields and all lists are atomic (whole-list ownership).
Docs: https://kubernetes.io/docs/reference/using-api/server-side-apply/ and https://kubernetes.io/docs/reference/using-api/api-concepts/#patch-and-apply
Known gotchas
fieldManager is required on apply requests — omitting it fails the request. Pick a stable per-controller name; changing it silently creates a second manager and manufactures conflicts against your own previous writes.
force=true must be UNSET for non-apply patch types — sending it with merge/strategic/JSON patch is rejected.
You cannot set .metadata.managedFields in the body of an apply request; the server owns that field.
Removing a field from your applied intent DELETES it from the live object if you were its sole owner. Trimming your manifest is a destructive operation, not a no-op.
Server-Side Apply does not use resourceVersion — the object need not be read first and no resourceVersion is required. Conflict detection is per-field via managedFields, not optimistic locking, so a 409 here means field ownership, not a stale read.
Clearing managedFields requires overwriting with a list containing one empty entry [{}]; setting it to an empty list [] is deliberately ignored.
Server-Side Apply has been stable and enabled by default since Kubernetes v1.22.
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