Help Center/ Elastic Cloud Server/ API Reference (Paris Regions)/ APIs (Recommended)/ Status Management/ Changing an ECS OS (Using an Image with Cloud-Init Installed)
Updated on 2024-07-23 GMT+08:00
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Changing an ECS OS (Using an Image with Cloud-Init Installed)

Function

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

This API is an asynchronous API. After the OS change request is successfully delivered, a job ID is returned. This does not mean the OS change is complete. You need to call the API by referring to Querying Task Execution Status to query the job status. The SUCCESS status indicates that the OS change is successful.

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

Constraints

  • You can only use an image with Cloud-Init or Cloudbase-Init installed.
  • Only a stopped ECS or an ECS on which reinstalling or changing the OS failed supports changing OS.
  • Only an ECS with a system disk supports changing OS.
  • You are not allowed to perform other operations when changing the OS. Otherwise, changing the OS will fail.

URI

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

Table 1 describes the parameters in the URI.
Table 1 Parameter description

Parameter

Mandatory

Description

project_id

Yes

Specifies the project ID.

For details about how to obtain the ID, see Obtaining a 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-change

Yes

Object

Changes an ECS OS. For details, see Table 3.
Table 3 os-change field description

Parameter

Mandatory

Type

Description

keyname

Yes

String

Specifies the key pair name.

userid

No

String

Specifies the user ID. When the keyname parameter is being specified, the value of this parameter is used preferentially. If this parameter is left blank, the user ID in the token is used by default.

imageid

Yes

String

Specifies the ID of the new image in UUID format.

You can obtain the image ID from the console or by following the instructions provided in "Querying Images" in Image Management Service API Reference.

metadata

No

Object

Specifies the metadata of the ECS for which the OS is to be changed.
Table 4 metadata field description

Parameter

Mandatory

Type

Description

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 the 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 
    IyEvYmluL2Jhc2gKZWNobyB1c2VyX3Rlc3QgPiAvaG9tZS91c2VyLnR4dA==
  • Windows 
    cmVtIGNtZAplY2hvIDExMSA+IGM6XGFhYS50eHQ=

Response

See Responses (Task).

Example Request

  • After the ECS OS is switched, use the password for login authentication. For security purposes, store the password in ciphertext in configuration files or environment variables. 
    POST https://{endpoint}/v2/{project_id}/cloudservers/{server_id}/changeos

{
    "os-change": {
        "userid": "7e25b1da389f4697a79df3a0e5bd494e", 
        "imageid": "e215580f-73ad-429d-b6f2-5433947433b0"
    }
}
  • Change the OS and use the key pair for login authentication after the OS change. 
    POST https://{endpoint}/v2/{project_id}/cloudservers/{server_id}/changeos

{
    "os-change": {
        "keyname": "KeyPair-350b", 
        "userid": "7e25b1da389f4697a79df3a0e5bd494e", 
        "imageid": "e215580f-73ad-429d-b6f2-5433947433b0"
    }
}

Example Response

See Responses (Task).

{      
    "job_id": "ff80808288d41e1b018990260955686a" 
}

Returned Values

See Returned Values for General Requests.

Error Codes

See Error Codes.

Parent topic: Status Management