Select a bidding mode for a preemptible instance

Comparison of bidding modes

The following table describes the bidding modes supported by preemptible instances.

Best practices for bidding modes

1. Make preparations.

   1. Create a preemptible instance and set the bidding mode to Use Automatic Bid (SpotAsPriceGo).

      For more information, see Create a preemptible instance. If you already created a preemptible instance, skip this step.

   2. View the details of the preemptible instance.

      For more information, see View instance information. In this example, two preemptible instances are created, as described in the following table. In subsequent steps, the O&M scripts for price monitoring are configured based on the details of the instances.

      Instance name	Region and zone	Instance type

      Instance name	Region and zone	Instance type
      Preemptible instance 1	Hangzhou Zone I	ecs.c5.xlarge
      Preemptible instance 2	Hangzhou Zone K	ecs.r6.xlarge

   3. Create the OOSServiceRole role for OOS by using Resource Access Management (RAM).

      For more information, see Use RAM to grant permissions to OOS. In the Select Policy section of the Grant Permission panel, select only the AliyunECSReadOnlyAccess policy.

   4. Add a DingTalk chatbot.

      When you add a DingTalk chatbot, select Custom Keywords for Security Settings and enter Monitor in the Custom Keywords field. In subsequent steps, OOS sends notifications by using the webhook URL of the chatbot.

2. Log on to the OOS console.

3. In the left-side navigation pane, choose Automated Task > Scheduled O&M.

4. On the Scheduled O&M page, click Create.

5. On the Create Scheduled O&M Task page, configure the parameters that are described in the following table and click Create.

   Parameter	Description

   Parameter	Description
   Scheduled Task Type	Select Executed Periodically and configure the following parameters: Execution Period: Use the default setting. The task is executed once per hour. Note The prices of preemptible instances change infrequently within a short period of time. We recommend that you configure the prices of preemptible instances to be checked at an interval of 1 hour. Time Zone: Specify a time zone based on your region. In this example, the default setting is used. End Time: Specify the end time of the task based on your business requirements. In this example, the default setting is used.
   Select Template	Enter ACS-ECS-AlarmWhenDiscountAndPriceExceedsThresholdInMultiZoneAndInstanceType in the search box. Then, select the template.
   Configure Template Parameters	Configure the following parameters based on the details of the created preemptible instances: RegionId: Select China (Hangzhou). ZoneId: Select Hangzhou Zone I and Hangzhou Zone K. InstanceType: Select ecs.c5.xlarge and ecs.r6.xlarge. TaskType: Configure this parameter based on your business requirements. Valid values: Discount: monitors real-time discounts. For example, if the pay-as-you-go price of an instance type is USD 0.400 per hour and the preemptible instance price of the instance type is USD 0.080 per hour, preemptible instances of the instance type offer a significant discount of 80% off the pay-as-you-go price. If you want to get notified when the discount for preemptible instances is higher than 75%, set TaskType to Discount and set Threshold to 25, which indicates a 75% discount. Price: monitors real-time prices. For example, assume that the pay-as-you-go price of an instance type is USD 0.400 per hour and the preemptible instance price of the instance type is USD 0.080 per hour. If you want to get notified when the preemptible instance price exceeds USD 0.090 per hour, set TaskType to Price and set Threshold to 0.090. Threshold: Specify a threshold. Configure this parameter based on the value of TaskType. Webhook: Specify the webhook URL of the DingTalk chatbot. RateControl: Use the default settings. Permissions: Select the OOSServiceRole role.
   Execution Settings(Optional)	Use the default settings. You can also configure the parameters based on your business requirements.

   After the scheduled task is executed, you can view the status of the task on the Scheduled O&M page.

6. Wait for the scheduled task to be executed or test the scheduled task.

   • After the scheduled task is executed, the system monitors the bid price of the preemptible instances in real time. If the price exceeds the specified threshold, a notification is sent by using the DingTalk chatbot.

   • In actual scenarios, the prices of preemptible instances do not fluctuate frequently and the execution result of the scheduled task is difficult to be verified. You can create a scheduled task and set the threshold to a value that triggers an alert. For example, if the price of a preemptible instance is USD 0.080 per hour, you can set the threshold to 0.040. The price of the preemptible instance remains higher than the threshold. Therefore, an alert is triggered when the scheduled task is executed, and a notification is sent by using the DingTalk chatbot.

References

You can call the DescribeSpotAdvice operation to query information about preemptible instances in a region in the previous 30 days. The information includes the average release rate of preemptible instances and the percentage of the average preemptible instance price relative to the pay-as-you-go instance price.

Take the following CLI command as an example, in which the China (Hangzhou) region is used:

aliyun ecs DescribeSpotAdvice --region cn-hangzhou --RegionId 'cn-hangzhou'