Trigger for Message Queue that sends messages to a Serverless Containers container
A trigger for Message Queue speeds up the processing of messages in a queue. It picks up messages from the queue and passes them to a Serverless Containers container for processing. Once the messages are successfully processed, the trigger deletes them from the queue, and if an error occurs, it places the messages back in the queue and sets a visibility timeout. If the queue does not have a Dead Letter Queue configured, a message will continue to be returned to a container until it is successfully processed or until its retention period expires.
Warning
- You can only create a trigger for a standard message queue.
- The trigger must be in the same cloud as the queue from which it reads messages.
- You can create only one trigger for each message queue.
When the trigger is running, requests to the message queue are free of charge.
Message Queue triggers require service accounts to read messages from a message queue and invoke a container. You can use the same service account for both operations.
For more information about creating a trigger for Message Queue, see Creating a trigger for Message Queue that sends messages to a Serverless Containers container.
Message batching
The batching settings allow sending several messages to a container at the same time. They set a top limit on a message batch size and its accumulation time. For example, if the size of a message group is 3, the container can receive groups with 1 to 3 messages.
Roles required for the proper operation of a trigger for Message Queue
- To create a trigger, you need:
viewerrole for a folder with a message queue the trigger reads messages from.viewerrole for the folder with the container that the trigger invokes.- Permission for the service account under which the trigger runs the operations. This permission comes with the iam.serviceAccounts.user and editor roles or higher.
- For the trigger to fire, service accounts need the following roles:
editorfor the folder with a message queue the trigger reads messages from.serverless.containers.invokerfor the folder with the container invoked by the trigger.
Read more about access management.
Message Queue trigger message format
After the trigger picks up a message from the queue, it forwards it to the container in the following format:
{
"messages":[
{
"event_metadata":{
"event_id":"cce76685-5828-4304-a83d-9564********",
"event_type":"yandex.cloud.events.messagequeue.QueueMessage",
"created_at":"2019-09-24T00:54:28.980441Z",
"cloud_id":"b1gvlrnlh2sd********",
"folder_id":"b1g88tflh2sd********",
},
"details":{
"queue_id":"yrn:yc:ymq:ru-central1:21i6v06sqmsa********:event-queue",
"message":{
"message_id":"cce76685-5828-4304-a83d-9564********",
"md5_of_body":"d29343907090dff4cec4a9a0********",
"body":"message body",
"attributes":{
"SentTimestamp":"1569285804456"
},
"message_attributes":{
"messageAttributeKey":{
"data_type":"StringValue",
"string_value":"value"
}
},
"md5_of_message_attributes":"83eb2d0afefb150c1ffe69f6********"
}
}
},
{
"event_metadata":{
"event_id":"1f32fd25-11fc-4c08-88e7-d871********",
"event_type":"yandex.cloud.events.messagequeue.QueueMessage",
"created_at":"2019-09-24T00:54:28.980492Z",
"cloud_id":"b1gvlrnlh2sd********",
"folder_id":"b1g88tflh2sd********",
},
"details":{
"queue_id":"yrn:yc:ymq:ru-central1:21i6v06sqmsa********:event-queue",
"message":{
"message_id":"1f32fd25-11fc-4c08-88e7-d871********",
"md5_of_body":"d29343907090dff4cec4a9a0********",
"body":"message body",
"attributes":{
"SentTimestamp":"1569285806456"
},
"message_attributes":{
"messageAttributeKey":{
"data_type":"StringValue",
"string_value":"value"
}
},
"md5_of_message_attributes":"83eb2d0afefb150c1ffe69f6********"
}
}
}
]
}