This topic describes how to manually add an ECS instance to a scaling group. You can add existing ECS instances to a scaling group to take full advantage of the computing resources.


The ECS instances to be manually added to a scaling group meet the following requirements:

  • The instances are in the same region as the scaling group.
  • The instances do not belong to any other scaling groups.
  • The instances are in the Running state.
  • The network type of the instances is classic network or Virtual Private Cloud (VPC). Take note of the following items:
    • When the network type of the scaling group is classic network, only ECS instances of the classic network type can be added to the scaling group.
    • When the network type of the scaling group is VPC, only ECS instances in the same VPC as the scaling group can be added to the scaling group.

The scaling group to which you want to manually add ECS instances meet the following requirements:

  • The scaling group is in the Enabled state.
  • The scaling group does not have ongoing scaling activities.

Background information

The active scaling configuration of a scaling group does not affect whether ECS instances can be manually added to the scaling group. You can manually add ECS instances without waiting for the cooldown period to expire. For more information, see Cooldown time.

Typically, Auto Scaling scales out sufficient ECS instances based on your configurations. However, if the instance inventory is insufficient or the sum of ECS instances to be added and existing ECS instances in the scaling group exceeds the maximum number of instances specified for the scaling group, the number of actually created instances may be less than what you specified. In these cases, check the configuration of the scaling group to troubleshoot the issue. If the issue persists, submit a ticket.


  1. Log on to the Auto Scaling console.
  2. In the left-side navigation pane, click Scaling Groups.
  3. In the top navigation bar, select a region.
  4. Find the target scaling group and use one of the following methods to open the details page of the scaling group:
    • Click the ID of the scaling group in the Scaling Group Name/ID column.
    • Click Manage in the Actions column.
  5. In the left-side navigation pane, click ECS Instances.
  6. Click the Manually Added tab.
  7. Click Add Existing Instance.
  8. In the dialog box that appears, add the selected ECS instances to the right-side list and then click OK.
    If you select Enable the scaling group to manage the instance lifecycle, ECS instances that are manually added to the scaling group will be removed and released during scale-in events.
    Warning Make sure that you have sufficient balance in your account. If you have overdue payments in your account, pay-as-you-go and preemptible instances will be stopped or even released. For information about status changes of ECS instances with overdue payments, see Overdue payments.