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Elastic Compute Service:AttachKeyPair

Last Updated:Jun 18, 2026

Bind an SSH key pair to one or more Linux instances.

Operation description

When you call this operation, take note of the following items:

  • Windows instances do not support SSH key pairs.

  • After you bind an SSH key pair to an instance, authentication by using a username and password is disabled.

  • If the instance is in the Running state, restart the instance (RebootInstance) for the SSH key pair to take effect.

  • If the instance is in the Stopped state, start the instance (StartInstance) for the SSH key pair to take effect.

  • If an SSH key pair is already bound to the instance, the new SSH key pair automatically replaces the original one.

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Test

RAM authorization

The table below describes the authorization required to call this API. You can define it in a Resource Access Management (RAM) policy. The table's columns are detailed below:

  • Action: The actions can be used in the Action element of RAM permission policy statements to grant permissions to perform the operation.

  • API: The API that you can call to perform the action.

  • Access level: The predefined level of access granted for each API. Valid values: create, list, get, update, and delete.

  • Resource type: The type of the resource that supports authorization to perform the action. It indicates if the action supports resource-level permission. The specified resource must be compatible with the action. Otherwise, the policy will be ineffective.

    • For APIs with resource-level permissions, required resource types are marked with an asterisk (*). Specify the corresponding Alibaba Cloud Resource Name (ARN) in the Resource element of the policy.

    • For APIs without resource-level permissions, it is shown as All Resources. Use an asterisk (*) in the Resource element of the policy.

  • Condition key: The condition keys defined by the service. The key allows for granular control, applying to either actions alone or actions associated with specific resources. In addition to service-specific condition keys, Alibaba Cloud provides a set of common condition keys applicable across all RAM-supported services.

  • Dependent action: The dependent actions required to run the action. To complete the action, the RAM user or the RAM role must have the permissions to perform all dependent actions.

Action

Access level

Resource type

Condition key

Dependent action

ecs:AttachKeyPair

update

*Instance

acs:ecs:{#regionId}:{#accountId}:instance/{#instanceId}

*KeyPair

acs:ecs:{#regionId}:{#accountId}:keypair/{#keypairName}

None None

Request parameters

Parameter

Type

Required

Description

Example

RegionId

string

Yes

The region ID of the SSH key pair. You can call DescribeRegions to query the most recent region list of Alibaba Cloud.

cn-hangzhou

KeyPairName

string

Yes

The name of the SSH key pair.

testKeyPairName

InstanceIds

string

Yes

The IDs of the instances to which you want to bind the SSH key pair. The value can be a JSON array that consists of up to 50 instance IDs. Separate multiple IDs with commas (,).

["i-bp1gtjxuuvwj17zr****", "i-bp17b7zrsbjwvmfy****", … "i-bp1h6jmbefj1ytos****"]

Response elements

Element

Type

Description

Example

object

KeyPairName

string

The name of the key pair.

testKeyPairName

RequestId

string

The request ID.

473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E

TotalCount

string

The total number of instances to which the key pair is bound.

2

FailCount

string

The number of instances to which the key pair failed to be bound.

0

Results

object

Result

array<object>

The binding results of the key pair.

object

Code

string

The operation status code returned. 200 indicates that the operation was successful.

200

Message

string

The operation information returned. When the value of Code is 200, the value of Message is successful.

successful

InstanceId

string

The instance ID.

i-m5eg7be9ndloji64****

Success

string

Indicates whether the request was successful.

true

Examples

Success response

JSON format

{
  "KeyPairName": "testKeyPairName",
  "RequestId": "473469C7-AA6F-4DC5-B3DB-A3DC0DE3C83E",
  "TotalCount": "2",
  "FailCount": "0",
  "Results": {
    "Result": [
      {
        "Code": "200",
        "Message": "successful",
        "InstanceId": "i-m5eg7be9ndloji64****",
        "Success": "true"
      }
    ]
  }
}

Error codes

HTTP status code

Error code

Error message

Description

400 InvalidKeyPairName.NotFound The specified KeyPairName does not exist in our records. The specified KeyPairName parameter does not exist.
400 InvalidInstanceIds.ValueNotSupported The specified parameter InstanceIds is not valid. The specified InstanceIds parameter is invalid.
400 DependencyViolation.IoOptimize The specified parameter InstanceIds is not valid. The specified instance ID is invalid. The specified instance is not an I/O optimized instance.
403 DependencyViolation.WindowsInstance The instance creating is windows, cannot use ssh key pair to login The specified instance is a Windows instance and does not support logons using SSH key pairs.
403 InstanceKeyPairLimitExceeded The specified instances are beyond the permitted range.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.