Auto Scaling:Automatically release EIPs of ECS instances

Procedure

If EIPs are bound to the ECS instances of your scaling group, the EIPs are not automatically released when you delete the ECS instances. If you want the EIPs to be automatically released in this case, you can combine the lifecycle hook feature with an OOS template. In this topic, the ACS-ESS-LifeCycleReleaseEipAddressFromInstance public template is used as an example to implement automatic release of EIPs during a scale-in. You must complete the following steps:

Step 1: Grant a RAM role the permissions on OOS

You must have the permissions to execute OOS templates. In the ACS-ESS-LifeCycleReleaseEipAddressFromInstance OOS template, the following resources are included for O&M purposes: ECS instances, Auto Scaling resources, and EIPs.

1. Log on to the RAM console.

2. In the left-side navigation pane, choose Identities > Roles.

3. Find OOSServiceRole and click Grant Permission in the Actions column.

   Add the required permissions for the OOSServiceRole RAM role that is assumed by OOS to complete the authorization.

4. In the Add Permissions panel, add the required permissions and click OK.

   The following table describes the parameters that are used in this example. For parameters that are not described in the table, use the default settings.

   Parameter	Description
   Authorized Scope	Select Alibaba Cloud Account.
   Select Policy	Select the following system policies: AliyunECSFullAccess, AliyunESSFullAccess, and AliyunEIPFullAccess.

Step 2: Create a lifecycle hook of the scale-in type and trigger a scale-in

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 the region where Auto Scaling is activated.

4. Find a scaling group and use one of the following methods to go to the scaling group details page:

   • Click the ID of the scaling group in the Scaling Group Name/ID column.

   • Click Details in the Actions column.

5. Create a lifecycle hook.

   1. In the upper part of the scaling group details page, click the Lifecycle Hook tab.

   2. Click Create Lifecycle Hook.

   3. Configure parameters based on your business requirements and click OK.

      The following table describes the parameters that are used in this example. For parameters that are not described in the table, use the default settings.

      Parameter	Description
      Name	Enter ESSHookForReleaseEip.
      Scaling Activity	Select Scale-in Event.
      Timeout Period	Configure the Timeout Period parameter based on your business requirements. Unit: seconds. In this example, the Timeout Period parameter is set to 300. Note The timeout period is the period of time during which you can perform custom operations on ECS instances. If the timeout period is shorter than what is required to perform the custom operations, the operations may fail. We recommend that you assess the time required and configure the Timeout Period parameter based on your business requirements.
      Default Execution Policy	Select Continue.
      Send Notification When Lifecycle Hook Takes Effect	In this example, the following configurations are used: Select OOS Template. Select Public Templates. Select the ACS-ESS-LifeCycleReleaseEipAddressFromInstance public template. In the ACS-ESS-LifeCycleReleaseEipAddressFromInstance public template, select OOSServiceRole for OOSAssumeRole. In Step 1, the permissions on ECS, Auto Scaling, and EIP are granted to the OOSServiceRole RAM role. OSS obtains these permissions after it assumes the OOSServiceRole RAM role.

6. Trigger a scale-in.

   A scale-in is triggered in this example by manually executing a scaling rule. You can also trigger scale-ins by using scheduled or event-triggered tasks.

   Note

   If scaling activities are triggered when you manually execute scaling rules, lifecycle hooks take effect. Lifecycle hooks do not take effect when you manually add or remove ECS instances to or from a scaling group.

   1. In the upper part of the page that appears, click the Scaling Rules and Event-triggered Tasks tab.

   2. On the Scaling Rules tab, click Create Scaling Rule.

   3. In the Create Scaling Rule dialog box, configure parameters based on your business requirements and click OK.

      The following table describes the parameters that are used in this example. For parameters that are not described in the table, use the default settings.

      Parameter	Description
      Rule Name	Enter Delete1.
      Rule Type	Select Simple Scaling Rule.
      Operation	Set the value to Remove 1 Instances.

   4. On the Scaling Rules tab, find the Delete1 scaling rule and click Execute in the Actions column.

   5. In the Execute Scaling Rule message, click OK.

   After the Delete1 scaling rule is executed, one ECS instance is to be removed. Due to the ESSHookForReleaseEip lifecycle hook, the ECS instance enters the Pending state and Auto Scaling notifies OOS to execute the O&M operations defined in the ACS-ESS-LifeCycleReleaseEipAddressFromInstance public template.

7. Check whether the execution result meets your expectations.

   You can go to the Elastic IP Addresses page to check whether the corresponding EIP exists. If the EIP does not exist, the operation is successful.

   Note

   If the ECS instance is deleted but the EIP is not released, go to the OOS console to check the execution of the O&M task.

(Optional) Step 3: Check the execution of an O&M task

1. Log on to the OOS console.

2. In the left-side navigation pane, choose Automated Tasks > Task Execution Management.

3. Filter the O&M task by start time and click Details in the Actions column.

4. On the execution details page that appears, view the related information.

   For example, you can view the execution ID and execution status in the Basic Information section. You can also click output or Log on the Execution Steps and Results page to view the execution details or logs. For more information, see View the details of an execution.

   Important

   If the O&M task failed, an error message is displayed on the execution details page.

FAQ

References

• If secondary elastic network interfaces (ENIs) that provide EIPs are bound to the ECS instances of your scaling group, the secondary ENIs are released but the EIPs are not when you delete the ECS instances. You can combine the lifecycle hook feature with OOS templates to implement automatic release of secondary ENIs and EIPs. For more information, see Automatically unbind secondary ENIs from ECS instances.

• You can also combine the lifecycle hook feature with OOS to implement automatic binding of EIPs or ENIs that provide EIPs to ECS instances. For more information, see the following links:

  • Automatically associate EIPs with ECS instances

  • Automatically bind secondary ENIs to ECS instances