# Adding an ECS to an ECS Group

#### Function

This API is used to add an ECS to an ECS group. The system automatically deploys the newly added ECS to a host that is different from the ones accommodating other ECSs in the ECS group.

#### Constraints

- The ECS to be added has been stopped.
- Only KVM ECSs can be added.
- Only the anti-affinity policy is supported. ECSs in the same ECS group are deployed on different hosts, improving service reliability.

#### URI

POST /v1/{project_id}/cloudservers/os-server-groups/{server_group_id}/action

Table 1 describes the parameters in the URI.

Table 1 Parameter description
Parameter | Mandatory | Description
--- | --- | ---
project_id | Yes | Specifies the project ID.
server_group_id | Yes | Specifies the ECS group ID.

#### Request

Table 2 describes the request parameters.

Table 2 Request parameters
Parameter | Mandatory | Type | Description
--- | --- | --- | ---
add_member | Yes | Object | Specifies the information of the ECS to be added to an ECS group. For details, see Table 3.

Table 3 add_member parameters
Parameter | Mandatory | Type | Description
--- | --- | --- | ---
instance_uuid | Yes | String | Specifies the ECS UUID.

#### Response

None

#### Example Request

    POST https://{endpoint}/v1/{project_id}/cloudservers/os-server-groups/{server_group_id}/action

    {
        "add_member": {
            "instance_uuid":"34dac9a0-c4a7-457b-bab2-e2c696e0e401"
        }
    }

#### Example Response

Status code 200, indicating that the operation is successful

#### Returned Values

See Returned Values for General Requests.

#### Error Codes

See Error Codes.

Parent topic: ECS Group Management