Auto Scaling automatically adjusts the number of computing resources (the number of instances required by business workloads) based on your predefined policies, enabling efficient handling of workload fluctuations, improving resource utilization, and reducing costs. For short-term business needs, Auto Scaling supports manual execution of scaling rules to quickly adjust the number of Elastic Compute Service (ECS) instances.
Scenario
Description
For temporary business needs, the number of servers to be added and the timing for their addition are uncertain, particularly when there are no metrics available for monitoring. In such cases, manual adjustment of the server count is necessary.
For example, if a company needs additional servers for temporary testing purposes, manual oversight is required to determine the number and timing of server adjustments.
Solution
You can manually execute scaling rules to increase or decrease the number of servers.
In addition to manually executing scaling rules, you can manually adjust the expected number of instances in a scaling group to manage the number of instances in the group. For more information, see Expected number of instances.
Benefits
No initial costs for resource setup
Auto Scaling creates and releases ECS instances based on your business requirements, which eliminates upfront costs related to resource setup. You need to only reserve computing resources to handle your daily business traffic.
Flexible scaling
By preparing the configurations for servers to be scaled out in advance, you can easily enable automatic scaling with just a few clicks. This significantly reduces resource and O&M costs.
Prerequisites
The first time you use Auto Scaling, you must complete Resource Access Management (RAM) user authorization.
The AliyunServiceRoleForAutoScaling service-linked role is created. For more information, see Service-linked role.
If you use Auto Scaling as a RAM user, the RAM user must be granted the AliyunESSFullAccess policy. For more information, see Grant permissions to a RAM user.
Step 1: Create a scaling group
A scaling group is a collection of instances that meet your business requirements and serves as the core unit of Auto Scaling. Auto Scaling adjusts the number of instances in scaling groups by adding or removing them as needed.
Go to the Scaling Groups page.
Log on to the Auto Scaling console.
In the left-side navigation pane, click Scaling Groups.
In the top navigation bar, select the region where Auto Scaling is activated.
In the upper-left corner of the Scaling Groups page, click Create.
On the Create by Form tab, configure the scaling group and click Create.
The following table describes the parameter settings used in this topic. Parameters that are not covered in the following table default to their default settings. 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 the template for automatically creating ECS instances at this stage. After the scaling group is created, you can proceed to create a scaling configuration.
Minimum Number of Instances
1
Specify the minimum number of instances in the scaling group. If the number of instances in the scaling group falls below this value, Auto Scaling will add ECS instances until the desired minimum is reached.
Maximum Number of Instances
5
Specify the maximum number of instances in the scaling group. If the number of instances exceeds this value, Auto Scaling will remove ECS instances until the number of instances falls below the specified 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. It includes 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.
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.
In the upper part of the details page, click the Instance Configuration Sources tab.
On the Scaling Configurations tab, click Create Scaling Configuration.
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 topic. Parameters not covered in the following table default to their default settings. 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. However, charges apply for ECS instances created during scale-out events. In this example, the pay-as-you-go billing method is used. For more information, see Billing overview of ECS.
Image and Instance
Instance Configuration Mode
Specify Instance Pattern
Select Specify Instance Pattern to choose specifications for ECS instances.
Instance Attribute Combination
2 vCPUs, 4 GiB Memory, Enterprise Level
Select the appropriate number of vCPUs and memory size for 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. This example uses a public image. In real-world scenarios, you can choose a custom image specific to 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. Outbound public bandwidth is charged separately, and the fees are included in your ECS instance costs.
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.
In the Preview Scaling Configuration dialog box, confirm the information and click Create.
In the The scaling configuration is created. message, click Enable.
In the Enable Scaling Configuration dialog box, click OK.
NoteIn a scaling group, you must enable one scaling configuration. After you enable a scaling configuration, the scaling configuration enters the Active state.
In the Enable Scaling Group message, click OK.
The scaling group must be enabled to allow Auto Scaling to scale instances automatically based on your business requirements.
In this example, the Minimum Number of Instances parameter is set to 1. When you enable the scaling group, Auto Scaling automatically creates one ECS instance from the enabled scaling configuration. 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 defines whether to add or remove instances from a scaling group.
On the details page of the scaling group, click the Scaling Rules and Event-triggered Tasks tab. Then, click the Scaling Rules tab.
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 Configure 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
The type of the scaling rule. In this example, select Simple Scaling Rule. 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 added or removed during each scaling event must not exceed 1,000.
Cooldown Time
Optional. Specify the cooldown period for the scaling rule. 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: Manually execute scaling rules to scale ECS instances
You can manually execute scaling rules based on your business needs. Auto Scaling automatically adds or removes ECS instances based on the defined scaling rules to adjust the instance count in your scaling group.
On the details page of the scaling group, click the Scaling Rules and Event-triggered Tasks tab. Then, click the Scaling Rules tab.
Find the scaling rule that you want to manually execute and click Execute in the Actions column.
In this example, the following operations are performed to verify the scaling effect:
Execute the scale-out rule to check whether an ECS instance is automatically created in the scaling group.
Execute the scale-in rule to check whether an ECS instance is automatically removed from the scaling group.