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Add an ECS instance

Last Updated: Mar 29, 2017

You can add an ECS instance to a scaling group. There are two types of ECS instances: Subscription and Pay-As-You-Go. The ECS instance to be added must meet the following conditions:

  • The ECS instance is in the same region as the scaling group.
  • The ECS instance is the type as specified in the active scaling configuration.
  • The ECS instance is running.
  • The ECS instance is not in any other scaling group.
  • The ECS instance can be the classic type or VPC, but has the following restrictions:
    • If the scaling group is the classic type, only classic type instances can be added.
    • If the scaling group is the VPC type, only instances belonging to the same VPC can be added.

To add an ECS instance, the scaling group must meet the following conditions:

  • The scaling group is active.
  • The scaling group is not executing any scaling activity.

When no scaling activity is being executed for the scaling group, adding an ECS instance is executed directly without waiting for the cool-down time.

A successful return indicates that the Auto Scaling service will shortly execute the scaling activity, but does not mean that the scaling activity will be successfully executed. Use the returned ScalingActivityID to check the scaling activity status.

If the number of ECS instances to be added by the scaling rule plus the number of existing ECS instances in the scaling group (Total Capacity) exceeds the MaxSize value, the operation fails.

Manually added ECS instances are not associated with the active scaling configuration in the scaling group.


  1. On the Scaling group management page, click Manage next to the scaling group.

  2. Click ECS instance list on the left side.

  3. Click Add existing instance.

add ecs instance

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