Function Compute:RabbitMQ triggers

Overview

Usage notes

• The ApsaraMQ for RabbitMQ instance that is the trigger source must be in the same region as the function in Function Compute.
• When the number of created custom event buses and the number of created event rules reach the upper limits, you cannot create a Message Queue for RabbitMQ trigger of the event mode.
• When the number of created event streams reaches the upper limit, you cannot create a Message Queue for RabbitMQ trigger of the event stream mode.

For information about the limits on the number of resources that can be created by using an Alibaba Cloud account in each region, see Limits.

Before you begin

• EventBridge
  • Activate EventBridge and grant permissions to a RAM user
• Function Compute
  • Create a service
  • Create a function
• ApsaraMQ for RabbitMQ
  • Activate Message Queue 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 Services & Functions.
2. In the top navigation bar, select a region. On the Services page, click the desired service.
3. On the Functions page, click the function that you want to manage.
4. On the function details page, click the Triggers tab, select the version or alias from the Version or Alias drop-down list, and then click Create Trigger.
5. In the Create Trigger panel, specify related parameters. After you specify the parameters, 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 custom trigger name.	rabbitmq-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 of a service, see Manage versions and Manage aliases.	LATEST
   RabbitMQ Instance	Select a ApsaraMQ for RabbitMQ instance.	amqp-cn-i7m2l6m2****
   Vhost	Select a vhost of a ApsaraMQ for RabbitMQ instance from the drop-down list.	myhost-1
   Queue	Select a queue of a ApsaraMQ for RabbitMQ instance from the drop-down list.	myqueue-1
   Invocation Method	Select a function invocation mode. Valid values: Sync Invocation: This mode is suitable for sequential invocations. When a single event or a batch of events trigger the function, Function Compute runs the function and waits for a response before it processes the next event or batch of events. The upper limit of the payload for a synchronous invocation request is 32 MB. For more information, see Synchronous invocations. Async Invocation: This mode allows you to quickly consume events. When a single event or a batch of events trigger the function, Function Compute immediately returns a response and continue to process the next event or batch of events During this process, the function is run in asynchronous mode. The upper limit of the payload for an asynchronous invocation request is 128 KB. For more information, see Overview.	Sync Invocation
   Message Push Mode	The underlying application mode that is used for pushing message data to Function Compute. Valid values: Event Mode: A single message is passed to the function as an event parameter. The event follows the CloudEvents specification. For information about the relationship between message content and CloudEvents, see Parameters. Event Stream Mode: One or more messages are pushed to Function Compute for batch processing based on your batch configurations. This model is suitable for scenarios in which end-to-end streaming data is processed.	Event Mode
   Trigger State	Specifies whether to enable the trigger immediately after it is created. By default, Enable Trigger is selected and the trigger is enabled after it is created.	N/A

   For more information about advanced configurations such as message pushing, retry, and dead letter configurations, see Advanced features of triggers.

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

Step 2: Configure the input parameters of the function

The ApsaraMQ for RabbitMQ event source is passed to the function in the form of event, which acts as the input parameter. You can also manually pass event to the function to trigger the function and test whether the code of the function is correct.

1. On the function details page, click the Code tab and click the icon. From the drop-down list that appears, select Configure Test Parameters.
2. In the Configure Test Parameters panel, click the Create New Test Event or Modify Existing Test Event tab, and specify Event Name and the event content. After you specify the parameters, click OK.
   Sample code of event in the event mode:

     {
       "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****"
           }
       }
   }

   Sample code of event in the event stream mode:

   [
         {
       "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 in data. For information about the parameters that are defined in the CloudEvents specification, see Overview.

   Parameter	Type	Example	Description
   body	Map		The content of the message.
   Hello	String	EventBridge	The user data.
   props	Map		The properties of the message.
   contentEncoding	String	utf-8	The format in which the content of the message is encoded.
   messageId	String	f7622d51-e198-41de-a072-77c1ead7****	The ID of the message. The ID of each message is unique.
   envelope	Map		The envelope information about the message.
   deliveryTag	Int	98	The tag of the message.
   exchange	String	N/A	The name of the exchange that sent the message.
   redeliver	Boolean	false	Indicates whether the message can be resent. Valid values: true: The message can be resent. false: The message cannot be resent.
   routingKey	String	housekeeping	The routing rule of the message.

Step 3: Write and test the function

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

1. On the function details page, click the Code tab, edit the function code in the code editor, and then click Deploy.
   This topic 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 the Code tab and click Test Function.
   After the function is executed, you can view the result on the Code tab.

References

To modify or delete an existing trigger, see Trigger management.