Function Compute:ApsaraMQ for RabbitMQ triggers

Overview

Usage notes

• 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 exceeds the upper limit, you can no longer create ApsaraMQ for RabbitMQ triggers.

For information about the limits on the number of resources that are used to create a trigger in one region by using a single Alibaba Cloud account, see Limits.

Before you start

• EventBridge

  • Activate EventBridge and grant permissions to a RAM user

• Function Compute

  • Create a function

• ApsaraMQ for RabbitMQ

  • Activate ApsaraMQ for RabbitMQ

  • Create an instance, a vhost, and a queue

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, follow the on-screen instructions to configure the parameters and click OK.

   The following table describes the basic parameters.

   Parameter	Description	Example
   Trigger Type	Select Message Queue for RabbitMQ from the drop-down list.	Message Queue for RabbitMQ
   Name	Enter a trigger name.	rabbitmq-trigger
   Version or Alias	Default value: LATEST. If you want to create a trigger for another version or alias, go back to the Function Details page and switch to the specified version or alias in the upper-right corner. For more information about versions and aliases, see Manage versions and Manage aliases.	LATEST
   RabbitMQ Instance	Select the ApsaraMQ for RabbitMQ instance that you created.	amqp-cn-i7m2l6m2****
   Vhost	Select the vhost that you created on the ApsaraMQ for RabbitMQ instance.	myhost-1
   Queue	Select the queue that you created on the ApsaraMQ for RabbitMQ instance.	myqueue-1
   Invocation Method	Select a function invocation method. Valid values: Sync Invocation: This method is suitable for sequential invocations. When an event or a batch of events triggers the function, Function Compute runs the function and waits for a response before the function processes the next event or batch of events. The maximum payload of a synchronous invocation request is 32 MB. For more information, see Synchronous invocations. Async Invocation: This method allows you to quickly consume events. When an event or a batch of events triggers the function, Function Compute immediately returns a response and continue processing the next event or batch of events. During this process, the function is executed in asynchronous mode. The maximum payload of an asynchronous invocation request is 128 KB. For more information, see Overview.	Sync Invocation
   Trigger State	Specify whether to enable the trigger immediately after it is created. By default, Enable Trigger is selected, which indicates that the trigger is enabled immediately after it is created.	N/A

   For information about advanced configurations such as push settings, retry policies, and dead-letter queues, see Advanced features of triggers.

   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 associated function

A source event in ApsaraMQ for Kafka is passed to the associated function as an input parameter in the form of event. You can manually pass event to the function to simulate event triggering and test the function to verify whether the 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.

   The following sample code provides an example on how to write 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. Click Test Function.

Additional information

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