Auto Scaling is an Alibaba Cloud service that automatically adjusts the number of Elastic Compute Service (ECS) instances based on workload changes and scaling policies. Auto Scaling helps ensure sufficient computing resources, prevent idle resources, and reduce costs. For short-term business needs, you can manually execute scaling rules to increase or decrease the number of ECS instances with just a few clicks.
Scenarios
Description
For temporary business needs, manual adjustment of servers is required because determining the number of servers to add and the timing for adding the servers is challenging, especially when no monitoring metric is available.
For example, if a company requires additional servers for testing purposes due to temporary business needs, manual oversight is required to determine the number of servers to add or remove and the timing for these adjustments.
Solutions
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 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.
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 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.
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 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.
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.
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.
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 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: Manually execute scaling rules to scale ECS instances
You can manually execute scaling rules based on your business requirements. Auto Scaling automatically creates or releases ECS instances based on the scaling rules to adjust the number of instances 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 desired scaling rule 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.
