<p>Registers instances that were created outside of AWS OpsWorks Stacks with a specified stack.</p> <note> <p>We do not recommend using this action to register instances. The complete registration operation includes two tasks: installing the AWS OpsWorks Stacks agent on the instance, and registering the instance with the stack. <code>RegisterInstance</code> handles only the second step. You should instead use the AWS CLI <code>register</code> command, which performs the entire registration operation. For more information, see <a href="https://docs.aws.amazon.com/opsworks/latest/userguide/registered-instances-register.html"> Registering an Instance with an AWS OpsWorks Stacks Stack</a>.</p> </note> <p>Registered instances have the same requirements as instances that are created by using the <a>CreateInstance</a> API. For example, registered instances must be running a supported Linux-based operating system, and they must have a supported instance type. For more information about requirements for instances that you want to register, see <a href="https://docs.aws.amazon.com/opsworks/latest/userguide/registered-instances-register-registering-preparer.html"> Preparing the Instance</a>.</p> <p> <b>Required Permissions</b>: To use this action, an IAM user must have a Manage permissions level for the stack or an attached policy that explicitly grants permissions. For more information on user permissions, see <a href="https://docs.aws.amazon.com/opsworks/latest/userguide/opsworks-security-users.html">Managing User Permissions</a>.</p>

{
  "success": true,
  "data": {
    "id": "abc123",
    "created_at": "2025-01-01T00:00:00Z"
  }
}

{
  "success": false,
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid request parameters"
  }
}