This API is used to update ECS metadata.

If the metadata does not contain the target field, the field is automatically added.
If the metadata contains the target field, the field value is automatically updated.
If the field in the metadata is not requested, the field value remains unchanged.

An ECS must be in active, stopped, paused, or suspended state, which is specified by OS-EXT-STS:vm_state.

POST /v2.1/{project_id}/servers/{server_id}/metadata

POST /v2/{project_id}/servers/{server_id}/metadata

Table 1 describes the parameters in the URI.

**Table 1** Parameter description
Parameter	Mandatory	Description
project_id	Yes	Specifies the project ID.
server_id	Yes	Specifies the ECS ID.

Table 2 describes the request parameters.

**Table 2** Request parameters
Parameter	Mandatory	Type	Description
metadata	Yes	Object	Specifies the user-defined metadata key-value pair. For a metadata key: It contains a maximum of 255 Unicode characters and cannot be left blank. A key can contain uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), hyphens (-), underscores (_), colons (:), and periods (.). For a metadata value: A value contains a maximum of 255 Unicode characters.

Table 3 describes the response parameters.

**Table 3** Response parameters
Parameter	Type	Description
metadata	Object	Specifies the user-defined metadata key-value pair.

POST https://{endpoint}/v2/{project_id}/servers/{server_id}/metadata
POST https://{endpoint}/v2.1/{project_id}/servers/{server_id}/metadata

{
    "metadata": {
        "key": "value"
    }
}

{
    "metadata":{
        "key":"value"
    }
}

Updating ECS Metadata