Create a scaling group

Last Updated: Nov 22, 2017

A scaling group is a collection of ECS instances with similar configuration deployed in an application scenario. It defines the maximum and minimum number of ECS instances in the group, associated Server Load Balancer and RDS instances, and other attributes.

See Removal policies to remove an ECS instance from a scaling group.

Parameter description

This operation creates a scaling group according to input parameters.

  • MaxSize and MinSize define the maximum and minimum number of ECS instances in the scaling group.

    • When the number of ECS instances (Total Capacity) in the scaling group is smaller than the MinSize value, Auto Scaling adds ECS instances to the group until the MinSize value is reached.

    • When the number of ECS instances (Total Capacity) in the scaling group is greater than the MaxSize value, Auto Scaling removes ECS instances from the group until the MaxSize value is reached.

  • DefaultCooldown specifies the default cool-down time for the scaling group.

    • During the cool-down time after a scaling activity (adding or removing ECS instances) is executed, the scaling group cannot execute any other scaling activity.

    • Currently, this only applies to the scaling activities triggered by the alarm tasks of CloudMonitor.

  • RemovalPolicy determines how ECS instances should be removed from the scaling group when multiple candidates for removal exist.

Considerations for working with Server Load Balancer

  • If a Server Load Balancer instance is specified for a scaling group, Auto Scaling automatically adds the ECS instances to the Server Load Balancer instance while adding them to the scaling group.

  • You must enable the specified Server Load Balancer instance.

  • You must enable the health chech for all listener ports of the Server Load Balancer instance. Otherwise, the scaling group creation will fail.

  • The default weight of ECS instances added to a Server Load Balancer instance is 50.

Considerations for working with RDS

If an RDS instance is specified for a scaling group, the scaling group adds the intranet IP addresses of the ECS instances in the group to the specified RDS instance’s access whitelist.

  • The specified RDS instance must be in the running state.

  • The specified RDS instance’s access whitelist must have room for more IP addresses.

  • The scaling group does not take effect immediately after creation. It must be enabled to trigger scaling rules and execute scaling activities.

Restrictions

  • The scaling group, Server Load Balancer instance, and RDS instance must be in the same region.

  • You can create 20 scaling groups at most.

Procedure

  1. On the Scaling Group List page, click Create Scaling Group.

    Create Scaling Group

  2. On the Create Scaling Group page, enter the Scaling Group Name.

    Create Scaling Group

  3. Enter the Maximum Number of Instances Allowed for Scaling (Unit) and Minimum Number of Instances Allowed for Scaling (Unit). If they are set to 1, an ECS instance is created automatically upon the creation of the scaling solution.

  4. Enter the Default Cool-down Time(Sec), Removal Policy and Network Type.

  5. Select the Sever Load Balancer and RDS database instances as needed.

  6. Click Submit.

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