Auto Scaling:Scale ECS instances by triggering event-triggered tasks

Scenario

Description

Solution

You can create event-triggered tasks to monitor CloudMonitor metrics. This allows for automatic execution of scaling rules when the metric data reaches the alerting thresholds. By using this method, you can effectively enable automatic scaling of servers based on your business workloads.

Benefits

• Zero upfront resource setup costs

  Auto Scaling creates and releases ECS instances based on your business requirements, eliminating the need for any upfront costs related to resource setup. You only need to reserve computing resources for daily business traffic.

• Automatic scaling

  Auto Scaling is integrated with CloudMonitor to monitor fluctuations in workloads, thereby efficiently executing automatic scaling of ECS instances. This integration aids in meeting business demands while simultaneously reducing resource and O&M costs.

Prerequisites

Step 1: Create a scaling group

A scaling group refers to a group of instances that meet your business requirements and serves as the fundamental unit of Auto Scaling. Auto Scaling adds instances to or removes instances from scaling groups.

1. Go to the Scaling Groups page.

   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.

2. In the upper-left corner of the Scaling Groups page, click Create.

3. On the Create by Form tab, configure the scaling group and click Create.

   The following table describes the parameter settings used in this example. Use the default settings for parameters that are not included in the table. For information about how to create a scaling group, see Create scaling groups.

   Parameter	Example	Description
   Scaling Group Name	test	Enter a name for the scaling group. The name must follow the format requirements displayed on the UI.
   Type	ECS	Select ECS, which specifies that the scaling group contains ECS instances.
   Instance Configuration Source	Create from Scratch	Do not specify a template used to automatically create ECS instances. After the scaling group is created, you can proceed to create a scaling configuration.
   Minimum Number of Instances	1	Specify the minimum instance limit. If the number of instances in the scaling group is less than the value of this parameter, Auto Scaling adds ECS instances to the scaling group until the number of ECS instances in the scaling group reaches the lower limit.
   Maximum Number of Instances	5	Specify the maximum instance limit. If the number of instances in the scaling group is greater than the value of this parameter, Auto Scaling removes ECS instances from the scaling group until the number of ECS instances in the scaling group drops below the upper limit.
   VPC	vpc-bp1jmxxau0lur929p****	Select a VPC for the ECS instances in the scaling group.
   vSwitch	vsw-2zeknnyw2ewufbs4z**** vsw-2zesy03h8eaf9fe0l****	Select one or more vSwitches for the ECS instances in the scaling group. We recommend that you select multiple vSwitches to improve the success rate of scale-out events.

Step 2: Create a scaling configuration and enable the scaling configuration and scaling group

A scaling configuration is a template used to create ECS instances during scale-out events, containing information such as the billing method, instance type, storage, and network settings. After you create a scaling configuration, you can enable the scaling configuration and then enable the scaling group.

1. Find the desired scaling group and use one of the following methods to open 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.

2. In the upper part of the details page, click the Instance Configuration Sources tab.

3. On the Scaling Configurations tab, click Create Scaling Configuration.

4. On the Create Scaling Configuration page, configure parameters to create a scaling configuration and then click Create.

   The following table describes the parameter settings used in this example. Use the default settings for parameters that are not included in the table. For more information about how to create a scaling configuration, see Create a scaling configuration of the ECS type.

   Section	Parameter	Example	Description
   Basic Information	Scaling Configuration Name	test	Enter a name for the scaling configuration. The name must follow the format requirements displayed on the UI.
   	Billing Method	Pay-as-you-go	Auto Scaling is free of charge. However, you are charged for the ECS instances that are created during scale-out events. In this example, the pay-as-you-go billing method is used. For more information, see Billing overview.
   Instance and Image	Instance Configuration Mode	Specify Instance Pattern	Select Specify Instance Pattern to select specifications for ECS instances.
   	Instance Attribute Combination	2 vCPUs, 4 GiB Memory, and Enterprise Level	Specify the number of vCPUs and the memory size of ECS instances based on your business requirements.
   	Select Image	Public Image: Alibaba Cloud Linux 3.2104 LTS 64-bit	Select an image to deploy ECS instances. In this example, a public image is used. In actual business scenarios, you can select the custom image of your application.
   Storage	System Disk	Enterprise SSD (ESSD), 40 GiB, and PL0	Select a system disk for ECS instances.
   Network and Security Group	Public IP Address	Assign Public IPv4 Address, Pay-by-bandwidth, and 1 Mbit/s bandwidth	Specify whether to assign public IP addresses to ECS instances. You are charged for the outbound public bandwidth. The bandwidth fees are included in your ECS instance fees.
   	Security Group	sg-bp18kz60mefsicfg****	Select an existing security group. For information about how to create a security group, see Create a security group.
   Management Settings	Logon Credentials	Set Later	Select Set Later, which requires you to manually configure passwords for ECS instances after you create the instances.

5. In the Preview Scaling Configuration dialog box, confirm the information and click Create.

6. In the The scaling configuration is created message, click Enable.

7. In the Enable Scaling Configuration dialog box, click OK.

   Note

   In a scaling group, you must enable one scaling configuration. After you enable a scaling configuration, the scaling configuration enters the Active state.

8. In the Enable Scaling Group message, click OK.

   After you enable the scaling group, Auto Scaling triggers automatic instance scaling based on your business requirements.

   In this example, the Minimum Number of Instances parameter is set to 1. In this case, Auto Scaling automatically creates one ECS instance based on the scaling configuration in the scaling group after you enable the scaling group. You can go to the Instances tab of the scaling group details page and check the instance information on the Auto Created tab.

   

Step 3: Create scaling rules

A scaling rule specifies whether to add instances to or remove instances from a scaling group.

1. On the details page of the scaling group, click the Scaling Rules and Event-triggered Tasks tab. Then, click the Scaling Rules tab.

2. Click Create Scaling Rule, configure parameters to create the scaling rule, and then click OK.

   In this example, simple scaling rules are created. For more information about how to create a scaling rule, see Manage scaling rules.

   Parameter	Description
   Rule Name	Enter a name for the scaling rule. The name must follow the format requirements displayed on the UI.
   Rule Type	In this example, simple scaling rules are created. For more information about scaling rules, see Overview.
   Operation	Specify the number of instances to add or remove when the scaling rule is executed. The number of instances to add or remove during each scaling event cannot exceed 1,000.
   Cooldown Time	Optional. Specify the period of time during which the scaling rule is cooled down. Unit: seconds. If you do not configure this parameter, the cooldown period of the scaling group takes effect. For more information, see Cooldown period.

   Repeat this step to create scale-out and scale-in rules. The following table describes the configurations used in this example.

   Scaling rule	Sample configuration
   Scale-out rule	Rule Name: add Rule Type: Simple Scaling Rule Operation: Add 1 Instance
   Scale-in rule	Rule Name: remove Rule Type: Simple Scaling Rule Operation: Remove 1 Instance.

Step 4: Create event-triggered tasks

Event-triggered tasks are designed to monitor specific metrics and collect real-time metric values. When these values meet the alerting conditions, Auto Scaling will trigger alerts and execute the specified scaling rules.

1. On the details page of the scaling group, click the Scaling Rules and Event-triggered Tasks tab. Then, click the Event-triggered Tasks tab.

2. On the Event-triggered Tasks (System) tab, click Create Event-triggered Task, configure parameters to complete task creation, and click OK.

   Note

   In this example, system metrics are specified in event-triggered tasks. You can also report custom metrics to CloudMonitor and specify the custom metrics in your event-triggered tasks. For more information, see Overview.

   The following table describes the parameter settings used in this topic. Any parameters that are not covered in the following table default to their default settings. For more information about event-triggered tasks, see Manage event-triggered tasks.

   Parameter	Description
   Name	Enter a name for the event-triggered task. The name must adhere to the format requirements displayed on the UI.
   Alert Condition	Define the condition under which alerts are reported when the metric data reaches a specified threshold. You must specify at least one metric. If you want to specify multiple metrics, click Add Metric. Take note of the following items: Metric: the name of the system metric that you want to monitor. For example, if you use the (ECS) CPU Utilization metric, the CPU utilization of all ECS instances in the scaling group is monitored. Statistical method: the method that you want to use to determine whether the metric data exceeds a specified threshold. You can use Average, Maximum, or Minimum as the statistical method. For example, if you use the Average method and specify a rule which is Average >= 70%, an alert is triggered when the average CPU utilization of all ECS instances in the scaling group reaches or exceeds 70%.
   Trigger Rule	Select the scaling rule that you want to execute when alerts are reported.

   Repeat this step to create event-triggered tasks that trigger the execution of scale-out and scale-in rules. Sample configurations:

   Event-triggered task	Example
   Event-triggered task for scale-out purposes	Name: Alarm-add Alert Condition: (ECS) CPU Utilization > Average (Average) > 70% Trigger Rule: add
   Event-triggered task for scale-in purposes	Name: alarm-remove Alert Condition: (ECS) CPU utilization > Average(Average) < 20% Trigger Rule: remove

Verify the effect of automatic scaling

After you create the event-triggered tasks, Auto Scaling continuously monitors the metric data of the scaling group in real time and executes the specified scaling rules when the alerting conditions are met.

In this example, the following results are achieved:

• When the CPU utilization of ECS instances in the scaling group exceeds 70%, one ECS instance is automatically added to the scaling group.

• When the CPU utilization of ECS instances in the scaling group drops below 20%, one ECS instance is automatically removed from the scaling group.

You can use the stress testing tool to simulate the test and confirm the scaling effect in the following ways:

• When the event-triggered tasks are triggered, go to the scaling group details page and choose Instances > Auto Create. Then, check the changes in the number of instances.

• When the event-triggered tasks are triggered, go to the scaling group details page and click the Scaling Activities tab. Then, check whether any scaling activity is generated. If a corresponding scaling activity is generated, click its ID to view the scaling activity details.