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

Prerequisites

Make sure that 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 can be either classic network or Virtual Private Cloud (VPC). However, you must take note of the following limits:
    • 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.

Make sure that 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 is not undergoing any scaling activities.

Background information

The scaling configuration of a scaling group does not affect whether ECS instances can be manually added to the scaling group. Therefore, you can manually add ECS instances even within the cooldown time. For more information about the cooldown time, see Cooldown time.

Typically, Auto Scaling scales out sufficient ECS instances based on your specifications. 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 upper limit of the group, the number of actually scaled out 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.

Procedure

  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. You can use either of the following methods to open the details page of a scaling group.
    • In the Scaling Group Name/ID column, click a scaling group name.
    • Click Manage in the Actions column corresponding to a scaling group.
  5. In the left-side navigation pane, click ECS Instances.
  6. Click Add Existing Instances.
  7. In the dialog box that appears, select available ECS instances in the left-side list and click > to add them to the scaling group. Then, click OK.