> ## Documentation Index > Fetch the complete documentation index at: https://docs.phala.com/llms.txt > Use this file to discover all available pages before exploring further. # Replace CVM annotations > Replaces every annotation of this CVM; an empty object clears them. The VMM applies the change at once, without a restart and without a compose change. Host tools that read annotations only when QEMU launches (for example memory tiers or vCPU pinning) see the new values after the CVM restarts. Other CVM updates never change annotations. Annotations are opaque key/value metadata for host-side tooling, such as a QEMU wrapper that reads the VM manifest. The dstack VMM stores them with the VM. They are not passed to the guest, not measured, and not part of the compose hash, so attestation does not cover them: tenants must not rely on them for security. Phala Cloud keeps no copy of annotations as CVM state: only the node's VMM holds them, and Cloud never copies or restores them. A replica starts without annotations; a relocated CVM keeps whatever its VMM manifest carries. A create request that carries annotations is recorded in the audit log. Requires the `cvm_annotations` feature flag (ERR-03-049) and dstack VMM 0.6.1 or newer on the node (ERR-03-050). ## OpenAPI ````yaml /openapi.json put /api/v1/cvms/{cvm_id}/annotations openapi: 3.1.0 info: title: Phala Cloud API version: 0.1.0 servers: - url: https://cloud-api.phala.com security: [] tags: - name: CVMs description: Confidential Virtual Machine (CVM) lifecycle management on Phala Network x-mint: href: https://cloud.phala.network/api-reference/cvms - name: Apps description: App template management and CVM deployment from app blueprints x-mint: href: https://cloud.phala.network/api-reference/apps - name: Webhooks description: Manage webhook endpoints and monitor delivery history x-mint: href: https://cloud.phala.network/api-reference/webhooks - name: SSH Keys description: SSH public key management for CVM access x-mint: href: https://cloud.phala.network/api-reference/ssh-keys - name: KMS description: >- Key Management Service — key derivation, on-chain anchoring, and inspection x-mint: href: https://cloud.phala.network/api-reference/kms - name: Instance Types description: Available hardware configurations for CVM deployment x-mint: href: https://cloud.phala.network/api-reference/instance-types - name: Attestations description: Remote attestation and TEE verification endpoints x-mint: href: https://cloud.phala.network/api-reference/attestations paths: /api/v1/cvms/{cvm_id}/annotations: put: tags: - CVMs - cvms-annotations summary: Replace CVM annotations description: >- Replaces every annotation of this CVM; an empty object clears them. The VMM applies the change at once, without a restart and without a compose change. Host tools that read annotations only when QEMU launches (for example memory tiers or vCPU pinning) see the new values after the CVM restarts. Other CVM updates never change annotations. Annotations are opaque key/value metadata for host-side tooling, such as a QEMU wrapper that reads the VM manifest. The dstack VMM stores them with the VM. They are not passed to the guest, not measured, and not part of the compose hash, so attestation does not cover them: tenants must not rely on them for security. Phala Cloud keeps no copy of annotations as CVM state: only the node's VMM holds them, and Cloud never copies or restores them. A replica starts without annotations; a relocated CVM keeps whatever its VMM manifest carries. A create request that carries annotations is recorded in the audit log. Requires the `cvm_annotations` feature flag (ERR-03-049) and dstack VMM 0.6.1 or newer on the node (ERR-03-050). operationId: handle_replace_annotations_api_v1_cvms__cvm_id__annotations_put parameters: - name: cvm_id in: path required: true schema: type: string title: Cvm Id requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/UpdateCvmAnnotationsRequest' responses: '200': description: The annotations now stored content: application/json: schema: $ref: '#/components/schemas/CvmAnnotationsResponse' '403': description: 'ERR-03-049: the cvm_annotations feature flag is off' content: application/json: schema: $ref: '#/components/schemas/StructuredErrorResponse' '404': description: CVM not found '409': description: 'ERR-03-050: the node''s dstack VMM is older than 0.6.1' content: application/json: schema: $ref: '#/components/schemas/StructuredErrorResponse' '422': description: An empty key or a non-string value '502': description: 'ERR-03-051: the node''s VMM failed to read or write the annotations' content: application/json: schema: $ref: '#/components/schemas/StructuredErrorResponse' '503': description: The node is offline or in maintenance components: schemas: UpdateCvmAnnotationsRequest: properties: annotations: additionalProperties: type: string type: object title: Annotations description: >- Opaque key/value metadata for host-side tooling. The dstack VMM stores it with the VM; it is not passed to the guest, not measured, and not part of the compose hash, so it is host configuration that attestation does not cover. Do not rely on it for security. Replaces every annotation; an empty object clears them. Keys must not be empty. examples: - memory_tier: fast type: object required: - annotations title: UpdateCvmAnnotationsRequest description: Full replacement of a CVM's annotations. CvmAnnotationsResponse: properties: annotations: additionalProperties: type: string type: object title: Annotations description: >- Opaque key/value metadata for host-side tooling. The dstack VMM stores it with the VM; it is not passed to the guest, not measured, and not part of the compose hash, so it is host configuration that attestation does not cover. Do not rely on it for security. type: object required: - annotations title: CvmAnnotationsResponse description: The annotations the node's VMM currently stores for one CVM. StructuredErrorResponse: properties: error_code: type: string title: Error Code message: type: string title: Message details: anyOf: - items: $ref: '#/components/schemas/ErrorDetail' type: array - type: 'null' title: Details suggestions: anyOf: - items: type: string type: array - type: 'null' title: Suggestions links: anyOf: - items: $ref: '#/components/schemas/ErrorLink' type: array - type: 'null' title: Links request_id: anyOf: - type: string - type: 'null' title: Request Id type: object required: - error_code - message title: StructuredErrorResponse description: OpenAPI shape for the global structured-error HTTP envelope. ErrorDetail: properties: field: anyOf: - type: string - type: 'null' title: Field value: anyOf: - {} - type: 'null' title: Value message: anyOf: - type: string - type: 'null' title: Message type: object title: ErrorDetail description: Detailed information about a specific aspect of the error. ErrorLink: properties: url: type: string title: Url label: type: string title: Label type: object required: - url - label title: ErrorLink description: A helpful link related to the error. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.