# Reinstalling an ECS OS (Using an Image with Cloud-Init Installed)

#### Function

This API is used to reinstall an ECS OS. During the system disk reinstallation using the original image, the data disks of the ECS remain unchanged.

After this API is called, the system uninstalls the system disk, uses the original image to create a system disk, and attaches it to the ECS. In this way, the OS is reinstalled.

#### Constraints

- You can only use an image with Cloud-Init or Cloudbase-Init installed.
- You can reinstall OS only on an ECS that is stopped or for which OS reinstallation has failed.
- You are not allowed to reinstall the OS of an ECS that does not have the system disk.
- You are not allowed to perform other operations when reinstalling the OS. Otherwise, reinstalling the OS will fail.

#### URI

POST /v2/{project_id}/cloudservers/{server_id}/reinstallos

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.

#### Request

Table 2 describes the request parameters.

Table 2 Request parameters
Parameter | Mandatory | Type | Description
--- | --- | --- | ---
os-reinstall | Yes | Object | Reinstalls an ECS OS. For details, see Table 3.

Table 3 os-reinstall field description
Parameter | Mandatory | Type | Description
--- | --- | --- | ---
keyname | Yes | String | Specifies the key pair name.
userid | Yes | String | Specifies the user ID. This parameter is mandatory when keyname is used.
metadata | No | Object | Specifies metadata of the reinstalled ECS. For more information, see Table 4.

Table 4 metadata field description
Parameter | Mandatory | Type | Description
--- | --- | --- | ---

BYOL

No

String

Specifies whether a user has the license of an image.

- If this parameter is set to true, the license file delivered with the image is used, indicating that BYOL is used.
- If this parameter is set to a value other than true, BYOL is not used, and the license file provided by the public cloud platform must be used.

The default value is not true, indicating that BYOL is not used.

user_data

No

String

Specifies the user data to be injected to the ECS during the creation. Text and text files can be injected.

NOTE:

- The content of user_data must be encoded with base64.
- The maximum size of the content to be injected (before encoding) is 32 KB.

For more details, see "Injecting User Data into ECSs" in Elastic Cloud Server User Guide.

Examples

Before base64 encoding:

- Linux

      #! /bin/bash
      echo user_test >> /home/user.txt

- Windows

      rem cmd
      echo 111 > c:\aaa.txt

After base64 encoding:

- Linux

      IyEgL2Jpbi9iYXNoDQplY2hvIHVzZXJfdGVzdCAmZ3Q7Jmd0OyAvaG9tZS91c2VyLnR4dA==

- Windows

      cmVtIGNtZAplY2hvIDExMSA+IGM6XGFhYS50eHQ=

__system__encrypted | No | String | Specifies encryption in metadata. The value can be 0 (encryption disabled) or 1 (encryption enabled). If this parameter does not exist, the system disk will not be encrypted by default.
__system__cmkid | No | String | Specifies the CMK ID, which indicates encryption in metadata. This parameter is used with __system__encrypted. NOTE: For details about how to obtain the CMK ID, see "Querying the List of CMKs" in Key Management Service API Reference.

#### Response

See Responses (Task).

#### Example Request

- Example URL request

      POST https://{endpoint}/v2/{project_id}/cloudservers/{server_id}/reinstallos

- Example request 1 (using a password to remotely log in to an ECS with OS reinstalled)

      {
          "os-reinstall": {
              "adminpass": "!QAZxsw2",
              "userid": "7e25b1da389f4697a79df3a0e5bd494e",
              "mode": "withStopServer"
          }
      }

- Example request 2 (using a key to remotely log in to an ECS with OS reinstalled)

      {
          "os-reinstall": {
              "keyname": "KeyPair-350b",
              "userid": "7e25b1da389f4697a79df3a0e5bd494e"
          }
      }

- Example request 3 (using a password to remotely log in a full-ECS-image-created ECS with OS reinstalled and system disk encrypted)

      {
          "os-reinstall": {
              "adminpass": "!QAZxsw2",
              "userid": "7e25b1da389f4697a79df3a0e5bd494e",
              "metadata": {
                    "__system__encrypted": "1",
                    "__system__cmkid": "83cdb52d-9ebf-4469-9cfa-e7b5b80da846"
              }
          }
      }

#### Example Response

See Responses (Task).

#### Returned Values

See Returned Values for General Requests.

#### Error Codes

See Error Codes.

Parent topic: Status Management