Function Overview

AS can use the Cloud Trace Service (CTS) to record resource operations. CTS can record operations performed on the management console, operations performed by calling APIs, and operations triggered within the cloud system.

If you have enabled CTS, when a call is made to the AS API, the operation will be reported to CTS which will then deliver the operation record to a specified OBS bucket for storage. With CTS, you can record operations associated with AS for later query, audit, and backtrack operations.

An AS group consists of a collection of instances and AS policies that have similar attributes and apply to the same application scenario. An AS group is the basis for enabling or disabling AS policies and performing scaling actions. The pre-configured AS policy automatically adds or deletes instances to or from an AS group, or maintains a fixed number of instances in an AS group.

When creating an AS group, specify an AS configuration for it. Additionally, add one or more AS policies for the AS group.

Creating an AS group involves the configuration of the maximum, minimum, and expected numbers of instances and the associated load balancer.

AS policies can trigger scaling actions to adjust the number of instances in an AS group. An AS policy defines the condition to trigger a scaling action and the operation to be performed in a scaling action. When the triggering condition is met, the system automatically triggers a scaling action.

AS policies can trigger scaling actions to adjust bandwidth or the number of instances in an AS group. An AS policy defines the conditions for triggering a scaling action and the operation that will be performed. When the triggering condition is met, a scaling action is triggered automatically.

AS supports the following policies:

• Alarm policy: AS automatically adjusts the number of instances in an AS group or sets the number of instances to the configured value when an alarm is generated for a configured metric, such as CPU Usage.
• Scheduled policy: AS automatically increases or decreases the number of instances in an AS group or sets the number of instances to the configured value at a specified time.
• Periodic policy: AS automatically increases or decreases the number of instances in an AS group or sets the number of instances to the configured value at a configured interval, such as daily, weekly, and monthly.

Before using AS to perform scaling actions, you must specify how to perform the scaling actions to dynamically expand resources.

If the demands change frequently, you can configure alarm-based policies to scale resources. When the conditions for invoking an AS policy are met, AS automatically changes the expected number of instances to trigger a scaling action to scale up or down resources.

To satisfy demands that change regularly, you can configure a scheduled or periodic policy to scale resources at specified time or periodically.

You can manually add or remove instances to or from an AS group, or changing the expected number of instances.

When instances are automatically removed from your AS group, the instances that are not in the currently used AZs will be removed first. Besides, AS will check whether instances are evenly distributed in the currently used AZs. If the load among AZs is unbalanced, AS balances load among AZs when removing instances. If the load among AZs is balanced, AS removes instances following the pre-configured instance removal policy.

Lifecycle hooks enable you to flexibly control addition and removal of ECS instances in AS groups and manage the lifecycle of ECS instances in AS groups.

Figure shows the instance lifecycle when a lifecycle hook is added to an AS group.

To control whether a particular instance can be removed automatically from an AS group, use instance protection. Once configured, when AS automatically scales in the AS group, the instance that is protected will not be removed.

If you want to stop distributing traffic to some instances in your AS group but do not want to remove them from the AS group, you can put the instances on standby. You can put one or more instances in your AS group on standby, and then stop or restart these instances without worrying about they are removed from the AS group.

You can automatically adjust your purchased EIP bandwidth and shared bandwidth using a bandwidth scaling policy. This section describes how to create a bandwidth scaling policy.

When creating a bandwidth scaling policy, you need to configure basic information. The system supports three types of bandwidth scaling policies: alarm-based, scheduled, and periodic.

The basic information for creating a bandwidth scaling policy includes the policy name, resource type, policy type, and trigger condition.

After the SMN service is provisioned, you can promptly send AS group information, such as successful instance increasing, failed instance increasing, successful instance decreasing, failed instance decreasing, or AS group exception to the user using the SMN service. This helps the user learn the AS group status.

To configure notification for an AS group, you need to specify a notification event and topic. You can configure up to five notifications for an AS group. The notification topic is pre-configured on the SMN console. When the live network complies with the notification scenario that matches the notification topic, the AS group sends a notification to the user.

This section describes the monitoring metrics reported by AS to Cloud Eye and defines the namespace for the metrics. You can use Cloud Eye to query monitoring metrics and alarms generated by AS.

The cloud platform provides Cloud Eye to help you obtain the running status of your ECS instances. This section describes how to view details of AS group metrics to obtain information about the status of the ECS instances in the AS group.

Setting alarm rules allows you to customize the monitored objects and notification policies and determine the running status of your ECS instances at any time.

If you need to assign different permissions to employees in your enterprise to access your AS resources, Identity and Access Management (IAM) is a good choice for fine-grained permissions management. IAM provides identity authentication, permissions management, and access control, helping you securely access to your HUAWEI CLOUD resources.

By using the APIs provided by AS, you can use all the functions of AS, for example, creating an AS group.