Scaling Your Website Dynamically

Scenarios

When service requirements change frequently and irregularly, you can configure alarm-based AS policies in your application system to adjust resources dynamically. When the conditions of a policy are met, the system automatically changes the expected number of instances to trigger a scaling action to add or remove instances. This reduces the workload of manual resource adjustments caused by service changes or peak hours, helping you save resource and labor costs.

Assume that you are an e-commerce vendor that runs a website on an ECS. If you plan to launch a big sales promotion at 00:00 on a certain day but the ECS is unable to handle service requests during peak hours, you can address this issue according the guidance of this section.

Procedure

Step 1: Create an AS Configuration

In this step, create an AS configuration using the example settings. For more information, see AS Configuration.

1. Log in to the AS console.
2. Click Create AS Configuration and set parameters.
   Figure 1 Creating an AS configuration
   
   
   

   Table 1 Parameters for creating an AS configuration

   Parameter	Example	Description
   Billing Mode	Pay-per-use	Resources will be billed based on the usage duration. You can provision or delete resources at any time. For more information, see Billing Overview.
   Region	CN-Hong Kong	For low network latency and fast resource access, select the region nearest to your target users. For more information, see Region and AZ.
   Name	as-config-3817	Enter a name for the AS configuration.
   Configuration Template	Create new template	Configure the specifications, image, disks, and other parameters for the instance.
   CPU Architecture	x86	x86 uses Complex Instruction Set Computing (CISC).
   Specifications	s7n.xlarge.2	Select a flavor based on service requirements. For more information, see A Summary List of x86 ECS Specifications.
   Image	CentOS 8.2 64bit(40GiB)	The example is a free public Linux image provided by Huawei Cloud.
   Disk	General Purpose SSD, 100 GiB	This is a system disk that will be created together with an instance. They are used to store the OS of each instance.
   Security Group	default	Use the default security group.
   EIP	Do not use	If the instances need to access the Internet, you can configure EIPs for them.
   Login Mode	Key pair	Set Login Mode to Key pair.
   Key Pair	KeyPair-2325	Use an existing or create a new key pair. Ensure that you have obtained the private key.
   Advanced Settings	Do not configure	-

3. Click Create Now.
4. Click Back to AS Configuration List to view the new AS configuration.
   Figure 2 Viewing an AS configuration
   

Step 2: Create an AS Group

In this step, create an AS group using the example settings. For more information, see AS Group.

1. Click Create AS Group and set parameters.
   Figure 3 Creating an AS group
   
   
   

   Table 2 Parameters for creating an AS group

   Parameter	Example	Description
   Region	CN-Hong Kong	For low network latency and fast resource access, select the region nearest to your target users. For more information, see Region and AZ.
   AZ	AZ1, AZ2, AZ3, AZ7	AZs are physically isolated but interconnected over an intranet.
   Multi-AZ Scaling Policy	Balanced	This policy ensures that the number of instances in each of the selected AZs is balanced.
   Name	as-group-test1	Enter a name for the AS group.
   Max. Instances	1	Specify the maximum number of instances in the AS group.
   Expected Instances	0	Specify the desired number of instances in the AS group.
   Min. Instances	0	Specify the minimum number of instances in the AS group.
   AS Configuration	as-config-3817	Select the AS configuration created in Step 1: Create an AS Configuration.
   VPC	vpc-default-smb	Use the default VPC and subnet. For more information, see VPC Network Planning Suggestions.
   Subnet	subnet-default-smb
   Load Balancing	Do not use	This parameter is optional. For more information, see Creating an AS Group.
   Instance Removal Policy	Oldest instance created from oldest AS configuration	With this policy, instances that use the oldest AS configuration are removed from the AS group first.
   EIP	Release	With this option, when an instance is removed from an AS group, its EIP will be released.
   Data Disk	Delete	With this option, when an instance is removed from the AS group, all data disks attached to it will be deleted
   Health Check Method	ECS health check	With this method, AS checks whether instances are running. If an instance fails the health check, AS removes it from the AS group.
   Health Check Interval	5 minutes	Specify the interval between health checks.
   Health Check Grace Period (s)	600	Specify how long AS must wait before checking the health status of an instance after the instance is enabled in an AS group.
   Enterprise Project	default	Specify the enterprise project where the AS group is managed. Instances in this AS group are also managed under the same project.

2. Click Create Now.
3. Click Back to AS Group List to view the new AS group.
   Figure 4 Viewing an AS group
   

Step 3: Add an AS Policy

1. In the AS group list, locate the AS group and click View AS Policy in the Operation column. Then, click Add AS Policy.
2. Configure the parameters for adding an AS policy.
   Figure 5 Parameters for adding an AS policy
   

   Table 3 Alarm-based AS policy parameters

   Parameter	Example	Description
   Policy Name	as-policy-e26c	Enter a name for the AS policy.
   Policy Type	Alarm	Set Policy Type to Alarm.
   Alarm Rule	Create	You can choose either to create a new alarm rule or use an existing one.
   Rule Name	as-alarm-43bd	Enter a name for the alarm rule.
   Monitoring Type	System monitoring	You can choose either System monitoring or Custom monitoring.
   Trigger Condition	CPU Usage Max. > 90%	-
   Monitoring Interval	5 minutes	-
   Consecutive Occurrences	3	-
   Enterprise Project	default	The default enterprise project is default.
   Alarm Policy Type	Simplified scaling	-
   Scaling Action	Add 2 instances	Specify an action and the number or percentage of instances. The value can be Add, Reduce, or Set to.
   Cooldown Period (s)	300	To prevent an alarm-based policy from being repeatedly triggered by the same event, you can set a cooldown period.

3. Click OK.

(Optional) Step 4: Manually Add Instances

1. Click the name of the AS group. Click the Instances tab.
2. Select the instance to be added and click Add.
   Figure 6 Manually adding instances
   
   

   Instances can be added to an AS group only when the group is enabled, no scaling action is in progress in it, and the number of instances in it is less than the maximum allowed.

(Optional) Step 5: View Monitoring Data

Click the name of the AS group and then click the Monitoring tab. You can view monitoring data changes of the AS group's scaling actions. AS can monitor CPU status in real time and perform scaling actions based on configured policies. This meets service requirements and reduces costs.

Figure 7 Viewing monitoring data