This API is used to modify the ECS metadata with a specified key.

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.

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

PUT /v2.1/{project_id}/servers/{server_id}/metadata/{key}

PUT /v2/{project_id}/servers/{server_id}/metadata/{key}

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.
key	Yes	Specifies the ECS metadata key.

Table 2 describes the request parameters.

**Table 2** Request parameters
Parameter	Mandatory	Type	Description
meta	Yes	Object	Specifies the user-defined metadata key 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: It contains a maximum of 255 Unicode characters.

Table 3 describes the response parameters.

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

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

{
    "meta":{
        "key":"value"
    }
}

{
    "meta":{
        "key":"value"
    }
}

Modifying ECS Metadata with a Specified Key