Function Compute:ApsaraMQ for RabbitMQ triggers

Overview

Limits

• The ApsaraMQ for RabbitMQ instance that is used as the trigger source must reside in the same region as the Function Compute function.

• If the number of created event streams reaches the upper limit, you can no longer create ApsaraMQ for RabbitMQ triggers.

For information about the limits on resources related to triggers in one region for each Alibaba Cloud account, see Limits.

Before you start

• EventBridge

  • Activate EventBridge and grant permissions to a RAM user

• Function Compute

  • Create an event function

• ApsaraMQ for RabbitMQ

  • Activate ApsaraMQ for RabbitMQ

  • Create an instance, a vhost, and a queue

Step 1: Create a trigger

After you create an ApsaraMQ for RabbitMQ queue, you need to log on to the Function Compute console, go to the function details page, click the Configurations tab, and then click Create Trigger in the Triggers page to create a trigger. After the trigger is created, click OK. The following figure shows the details.

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

Step 2: (Optional) Configure input parameters

ApsaraMQ for RabbitMQ passes an event source to a function in the form of event as input parameters. You can use code to parse and process event. You can manually pass event to the function to simulate the trigger event to test whether the function code is correct.

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.

   Sample code of event:

   [
         {
       "id":"bj694332-4cj1-389e-9d8c-b137h30b****",
       "source":"RabbitMQ-Function-rabbitmq-trigger",
       "specversion":"1.0",
       "type":"amqp:Queue:SendMessage",
       "datacontenttype":"application/json;charset=utf-8",
       "subject":"acs:amqp:cn-hangzhou:164901546557****:/instances/amqp-cn-tl32e756****/vhosts/eb-connect/queues/housekeeping",
       "time":"2021-08-12T06:56:40.709Z",
       "aliyunaccountid":"164901546557****",
       "aliyunpublishtime":"2021-10-15T08:58:55.140Z",
       "aliyunoriginalaccountid":"164901546557****",
       "aliyuneventbusname":"RabbitMQ-Function-rabbitmq-trigger",
       "aliyunregionid":"cn-chengdu",
       "aliyunpublishaddr":"42.120.XX.XX",
       "data":{
           "envelope":{
               "deliveryTag":98,
               "exchange":"",
               "redeliver":false,
               "routingKey":"housekeeping"
           },
           "body":{
               "Hello":"RabbitMQ"
           },
           "props":{
               "contentEncoding":"UTF-8",
               "messageId":"f7622d51-e198-41de-a072-77c1ead7****"
           }
       }
       },
       {
       "id":"bj694332-4cj1-389e-9d8c-b137h30b****",
       "source":"RabbitMQ-Function-rabbitmq-trigger",
       "specversion":"1.0",
       "type":"amqp:Queue:SendMessage",
       "datacontenttype":"application/json;charset=utf-8",
       "subject":"acs:amqp:cn-hangzhou:164901546557****:/instances/amqp-cn-tl32e756****/vhosts/eb-connect/queues/housekeeping",
       "time":"2021-08-12T06:56:40.709Z",
       "aliyunaccountid":"164901546557****",
       "aliyunpublishtime":"2021-10-15T08:58:55.140Z",
       "aliyunoriginalaccountid":"164901546557****",
       "aliyuneventbusname":"RabbitMQ-Function-rabbitmq-trigger",
       "aliyunregionid":"cn-chengdu",
       "aliyunpublishaddr":"42.120.XX.XX",
       "data":{
           "envelope":{
               "deliveryTag":98,
               "exchange":"",
               "redeliver":false,
               "routingKey":"housekeeping"
           },
           "body":{
               "Hello":"RabbitMQ"
           },
           "props":{
               "contentEncoding":"UTF-8",
               "messageId":"f7622d51-e198-41de-a072-77c1ead7****"
           }
       }
       }
   ]

   The following table describes the parameters contained in data. For information about parameters that are defined in the CloudEvents specification, see Overview.

   Parameter	Type	Example	Description
   body	Map		The message body.
   Hello	String	EventBridge	The user data.
   props	Map		The message attributes.
   contentEncoding	String	utf-8	The format in which the message body is encoded.
   messageId	String	f7622d51-e198-41de-a072-77c1ead7****	The message ID. The ID of each message is unique.
   envelope	Map		The information about the message envelope.
   deliveryTag	Int	98	The message tag.
   exchange	String	None	The name of the exchange that sends the message.
   redeliver	Boolean	false	Specifies whether the message can be resent. Valid values: true false
   routingKey	String	housekeeping	The routing rule of the message.

Step 3: Write function code and test the function

After the trigger is created, you can write function code and test the function to verify whether the code is correct. When events that are generated by ApsaraMQ for RabbitMQ are delivered to Function Compute by using EventBridge, the trigger automatically triggers the function.

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

   The following sample code provides an example of function code 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. Test the function.

   Method 1: If you configure event to simulate an event source, click Test Function.

   Method 2: Log on to the ApsaraMQ for RabbitMQ console, select the topic that you created, and then click Send Message. The following figure shows an example.

   

3. After the execution is complete, view the result in Real-time Logs.

   

More information

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