Function Compute:Configure event triggers for Alibaba Cloud services

Overview

When you submit a request to create a trigger in the Function Compute console, Function Compute automatically creates an event rule on the default event bus. The rule is named in the Function name-Trigger name format. After the trigger is created, you can view the trigger information in the Function Compute console. You can also view the automatically created event rule in the EventBridge console. When an event of the specified type is delivered from the event source to the event bus, the function associated with the trigger is executed.

Usage notes

• You can create a maximum of 10 event rules on the default event bus for Alibaba Cloud services in EventBridge. If you reach the limit, you cannot create more event triggers for Alibaba Cloud services.

• You cannot use Serverless Devs to create event triggers for Alibaba Cloud services.

Prerequisites

• EventBridge: Activate EventBridge and grant permissions

• Function Compute: Create a function

Step 1: Create a trigger

1. Log on to the Function Compute console. In the left-side navigation pane, click Functions.

2. In the top navigation bar, select a region. On the Functions page, click the function that you want to manage.

3. On the Function Details page, click the Configurations tab. In the left-side navigation pane, click Triggers. Then, click Create Trigger.

4. In the Create Trigger panel, configure the parameters and click OK.

   Parameter	Procedure	Example
   Trigger Type	Select Elastic Compute Service (ECS).	Elastic Compute Service (ECS)
   Name	Enter a custom name for the trigger.	ecs-trigger
   Version Or Alias	The default value is LATEST. If you want to create a trigger for another version or alias, switch to the specified version or alias in the upper-right corner of the function details page. For more information about versions and aliases, see Manage versions and Manage aliases.	LATEST
   Event Type	Select Custom Event Types or Select All Event Types. If you select Custom Event Types, you can select one or more event types of ECS.	Disk Retained
   Event Pattern Content	You cannot manually edit the content. After you select an event type for the Event Type parameter, the event pattern content is automatically populated. For more information about event patterns, see Event patterns.	{ "source": [ "acs.ecs" ], "type": [ "ecs:Disk:ConvertToPostpaidCompleted" ] }
   Invocation Method	Select an invocation method for the function. Valid values: Synchronous Invocation: This is the default invocation method. An event triggers a function. After the function execution is complete, Function Compute returns the execution result. For more information, see Synchronous invocations. Asynchronous Invocation: This method is suitable for functions that have long scheduling latencies. After an event triggers a function, Function Compute immediately returns a response and ensures that the function is successfully executed at least once. However, the detailed execution result is not returned. For more information, see Overview.	Synchronous Invocation
   Trigger State	Specifies whether to enable the trigger immediately after it is created. By default, Enable Trigger is selected. This means the trigger is enabled after it is created.	Enable Trigger

   After the trigger is created, it is displayed on the Triggers tab. To modify or delete a trigger, see Trigger management.

Step 2: Configure function input parameters

An ECS event is passed to the function as the event input parameter. You can manually pass the event to the function to simulate an event trigger.

1. On the Code tab of the function details page, click the icon next Test Function and select Configure Test Parameters from the drop-down list.

2. In the Configure Test Parameters panel, select Create New Test Event or Edit Existing Test Event, enter the event name and event content, and then click OK.

   The following code shows the format of the event parameter. For more information about the event content for all supported Alibaba Cloud service event sources, see Alibaba Cloud service event sources.

   {
       "datacontenttype": "application/json;charset=utf-8",
       "aliyunaccountid": "123456789098****",
       "data": {
           "result": "accomplished",
           "diskId": "d-bp11ba7acc69nkta****"
       },
       "subject": "acs:ecs:cn-hangzhou:123456789098****:disk/d-bp11ba7acc69nkta****",
       "source": "acs.ecs",
       "type": "ecs:Disk:ConvertToPostpaidCompleted",
       "aliyunpublishtime": "2021-01-18T03:58:31.762Z",
       "specversion": "1.0",
       "aliyuneventbusname": "default",
       "id": "70c0414c-b260-4923-b584-1d6e5646****",
       "time": "2021-01-18T11:58:31.125+08:00",
       "aliyunregionid": "cn-hangzhou",
       "aliyunpublishaddr": "172.25.XX.XX"
   }

   The following table describes the event parameters.

   Parameter	Type	Example	Description
   datacontenttype	String	application/json;charset=utf-8	The content format of the data parameter. The datacontenttype parameter supports only the application/json format.
   aliyunaccountid	String	123456789098****	The ID of your Alibaba Cloud account.
   data	Struct	{ "result": "accomplished", "diskId": "d-bp11ba7acc69nkta****" }	The event content. The value is a JSON object. The content is determined by the service that generates the event. CloudEvents may contain context that is provided by the event producer when the event occurs. This information is encapsulated in the data parameter.
   subject	String	acs:ecs:cn-hangzhou:123456789098****:disk/d-bp11ba7acc69nkta****	The subject of the event.
   source	String	acs.ecs	The event source.
   type	String	ecs:Disk:ConvertToPostpaidCompleted	The event type.
   aliyunpublishtime	Timestamp	2021-01-18T03:58:31.762Z	The time when the event was received.
   specversion	String	1.0	The version of the CloudEvents protocol.
   aliyuneventbusname	String	default	The name of the event bus that receives the event.
   id	String	70c0414c-b260-4923-b584-1d6e5646****	The event ID.
   time	Timestamp	2021-01-18T11:58:31.125+08:00	The time when the event occurred.
   aliyunregionid	String	cn-hangzhou	The region where the event was received.
   aliyunpublishaddr	String	172.25.XX.XX	The address of the server that receives the event.

Step 3: Write and test the function code

After you create the ECS trigger, you can write and test the function code to verify that it works correctly. In a production environment, when an event from the ECS event source is delivered to Function Compute through EventBridge, the trigger automatically executes the function.

1. On the function details page, click the Code tab. Write the code in the code editor and click Deploy Code.

   The following code provides an example in Node.js.

   'use strict';
   /*
   To enable the initializer feature
   please implement the initializer function as below:
   exports.initializer = (context, callback) => {
     console.log('initializing');
     callback(null, '');
   };
   */
   exports.handler = (event, context, callback) => {
     console.log("event: %s", event);
     // Parse the event parameters and process the event. 
     callback(null, 'return result');
   }

2. Click Test Function.

More information

To modify or delete an existing trigger, see Manage triggers.