# Adding a Tag to an ECS

This API is used to add a tag to an ECS.

You are required to use the HTTP header X-OpenStack-Nova-API-Version: 2.26 to specify the microversion on the client.

#### Constraints

- The tag contains a maximum of 80 characters.
- A tag can only consist of digits, letters, hyphens (-), and underscores (_).
- A maximum of 50 tags can be added to an ECS.
- An empty tag cannot be created.

#### URI

PUT /v2.1/{project_id}/servers/{server_id}/tags/{tag}

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.

tag

Yes

Specifies the key of the tag to be added.

For details about key rules, see Tag Types.

NOTE:

Tag functions have been upgraded on the public cloud. If the tags added before the function upgrade are in the format of "Key.Value", query tags using "Key".

For example, an existing tag is "a.b". The tag can be queried in the format of "tag=a.b" before and in the format of "tag=a" now according to the new tag rules.

#### Request

None

#### Response

Table 2 Response parameters
Parameter | Type | Description
--- | --- | ---
message | String | Example: "<br /><br />\n\n\n"
code | String | Example: "201 Created"
title | String | Example: "Created"

#### Example Request

    PUT https://{endpoint}/v2.1/{project_id}/servers/{server_id}/tags/{tag}

#### Example Response

By default, the response is in HTML format.

    <html>
    <head>
          <title>201 Created</title>
    </head>
    <body>
          <h1>201 Created</h1>
          <br /><br />

    </body>
    </html>

JSON format

    {
       "message": "<br /><br />\n\n\n",
       "code": "201 Created",
       "title": "Created"
    }

#### Returned Values

See Returned Values for General Requests.

Parent topic: Tag Management