Function Compute:Configure event triggers for Alibaba Cloud services

Overview

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

Usage notes

• You can create up to 10 event rules in the system even bus default in EventBridge. If the upper limit is reached, you can no longer create event triggers for Alibaba Cloud services.

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

Before you start

• EventBridge: Activate EventBridge and grant permissions to a RAM user

• 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 parameters and click OK.

   Parameter	Description	Example
   Trigger Type	Select Elastic Compute Service (ECS) from the drop-down list.	Elastic Compute Service (ECS)
   Name	Enter a trigger name.	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	After you set the Event Type parameter, the event pattern content is automatically populated. You cannot modify the content. For more information about event patterns, see Event patterns.	{ "source": [ "acs.ecs" ], "type": [ "ecs:Disk:ConvertToPostpaidCompleted" ] }
   Invocation Method	Specify the function invocation method. Valid values: Synchronous Invocation: After an event triggers the execution of a function, Function Compute returns the result when the execution is complete. This is the default value. For more information, see Synchronous invocations. Asynchronous Invocation: After an event triggers the execution of 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 after it is created. By default, Enable Trigger is selected and 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 Manage triggers.

Step 2: Configure the input parameters of the function

The ECS event source is passed to the function in the form of event, which acts as an input parameter. You can manually pass event to the function to trigger the function.

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, click the Create New Test Event or Modify Existing Test Event tab, enter the event name and event content, and then click OK.

   The following sample code provides an example of event. For more information about the supported events of Alibaba Cloud services, 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 parameters that are contained in event.

   Parameter	Type	Example	Description
   datacontenttype	String	application/json;charset=utf-8	The content type of the data parameter. Only the application/json content type is supported.
   aliyunaccountid	String	123456789098****	The ID of the Alibaba Cloud account.
   data	Struct	{ "result": "accomplished", "diskId": "d-bp11ba7acc69nkta****" }	The event content. The value is a JSON object, which is determined by the event source that produces the event. CloudEvents may contain the context given 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 event subject.
   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 specification.
   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 IP address of the server that receives the event.

Step 3: Write and test the function

After you create the ECS trigger, you can write function code and test the function to verify whether the code is correct. When the events that are generated by the ECS event sources are delivered to Function Compute from EventBridge, function execution is automatically triggered.

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

   The following uses the Node.js function code as an example.

   '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.

References

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