## POST /api/v2/placement-groups/{id}/members

**Add a VPS to a placement group**

Add a VPS to Group A, B, or C inside the placement group. Servers in different groups are kept away from each other.

### Related Endpoints

- `DELETE /api/v2/placement-groups/{id}/members/{vpsId}`: Remove a VPS from a placement group
- `GET /api/v2/placement-groups/{id}`: Get VPS placement group detail
- `PATCH /api/v2/placement-groups/{id}`: Rename a VPS placement group

### Headers

- `Accept`: application/json
- `Authorization`: Bearer YOUR_API_KEY
- Required API scope: `write:vm`
- `Content-Type`: application/json

### Parameters

- `id` (path, string, required): Placement group public ID. Example: `id_01hxa3b4c5d6e7f8g9h0j1k2m3`

### Request Body

- `vpsId` (string, required): VPS public ID from `GET /api/v2/placement-groups/candidates` or `GET /api/v2/vps`. Example: `vps_01hxa3b4c5d6e7f8g9h0j1k2m3`
- `placementSet` (string, optional): Customer-defined member group. Servers in different sets are kept away from each other. Defaults to `a`. Example: `a`
  Allowed values: a, b, c

### Request Example

```bash
curl -X POST "https://cloud.hostup.se/api/v2/placement-groups/id_01hxa3b4c5d6e7f8g9h0j1k2m3/members" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{
    "vpsId": "vps_01hxa3b4c5d6e7f8g9h0j1k2m3",
    "placementSet": "a"
  }'
```

```json
{
  "vpsId": "vps_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "placementSet": "a"
}
```

### Responses

#### 201 - Updated placement group detail.
```json
{
  "id": "pg_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "name": "Production database",
  "policy": "spread",
  "health": "ok",
  "needsAttention": false,
  "compatibilityKey": "pgcmp_9f6a3b2c1d0e8a7b",
  "members": [
    {
      "vpsId": "vps_01hxa3b4c5d6e7f8g9h0j1k2m3",
      "name": "db-primary",
      "instanceUrl": "/instance/vps_01hxa3b4c5d6e7f8g9h0j1k2m3",
      "placementSet": "a",
      "status": "placed",
      "addedAt": "2026-06-28T10:02:00.000Z"
    }
  ],
  "actions": {
    "canRename": {
      "allowed": true,
      "reason": null
    },
    "canDelete": {
      "allowed": true,
      "reason": null
    },
    "canAddMember": {
      "allowed": true,
      "reason": null
    },
    "canResolve": {
      "allowed": false,
      "reason": "not_needed"
    }
  },
  "createdAt": "2026-06-28T10:00:00.000Z",
  "updatedAt": "2026-06-28T10:05:00.000Z"
}
```

#### 400 - Invalid request. The response body is an RFC 7807 Problem Details document.
```json
{
  "type": "https://developer.hostup.se/errors/invalid_request",
  "title": "Invalid request",
  "status": 400,
  "detail": "The request body failed validation.",
  "code": "invalid_request",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z",
  "errors": [
    {
      "pointer": "/items/0/domainName",
      "detail": "`domainName` is required.",
      "code": "invalid_request"
    }
  ]
}
```

#### 401 - Unauthorized. Authentication is required.
```json
{
  "type": "https://developer.hostup.se/errors/unauthorized",
  "title": "Unauthorized",
  "status": 401,
  "detail": "Authentication is required.",
  "code": "unauthorized",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 403 - Forbidden. The caller lacks a required scope or does not own the resource.
```json
{
  "type": "https://developer.hostup.se/errors/forbidden",
  "title": "Forbidden",
  "status": 403,
  "detail": "The caller lacks a required scope or does not own the resource.",
  "code": "forbidden",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 404 - Not found. The resource does not exist or is not owned by the caller.
```json
{
  "type": "https://developer.hostup.se/errors/not_found",
  "title": "Not found",
  "status": 404,
  "detail": "The requested resource could not be found.",
  "code": "not_found",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 409 - The VPS cannot join this placement group. Known `code` values are `already_grouped`, `different_location`, `server_not_eligible`, and `placement_group_limit_reached`.
```json
{
  "type": "https://developer.hostup.se/errors/server_not_eligible",
  "title": "Server can't be added",
  "status": 409,
  "detail": "This VPS can't be added to this placement group.",
  "code": "server_not_eligible",
  "instance": "/api/v2/placement-groups/pg_01hxa3b4c5d6e7f8g9h0j1k2m3/members",
  "requestId": "00000000-0000-0000-0000-000000000000",
  "timestamp": "2026-06-28T10:05:00.000Z"
}
```

#### 429 - Rate limited. Retry after the limit resets. 429 responses include `Retry-After` seconds plus `X-RateLimit-*` headers.
```json
{
  "type": "https://developer.hostup.se/errors/rate_limit_exceeded",
  "title": "Too many requests",
  "status": 429,
  "detail": "Too many requests. Retry after the limit resets.",
  "code": "rate_limit_exceeded",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 500 - Internal error. Retry later or contact support if the issue persists.
```json
{
  "type": "https://developer.hostup.se/errors/internal_error",
  "title": "Internal server error",
  "status": 500,
  "detail": "An unexpected error occurred. Retry later or contact support if the issue persists.",
  "code": "internal_error",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```