This topic describes how to create a Function Compute sink connector to synchronize data from a source topic in your Message Queue for Apache Kafka instance to a function in Function Compute.

Prerequisites

The following requirements are met:
  • Message Queue for Apache Kafka
    • The connector feature is enabled for the Message Queue for Apache Kafka instance. For more information, see Enable the connector feature.
    • A topic is created in the Message Queue for Apache Kafka instance. For more information, see Step 1: Create a topic.

      In this example, the topic is named fc-test-input.

  • Function Compute
    • A function is created in Function Compute. For more information, see Create a function in the Function Compute console.
      Important The function that you create must be an event function.

      In this example, an event function named hello_world is created for the guide-hello_world service that runs in the Python runtime environment. Function code: 

      # -*- coding: utf-8 -*-
import logging

# To enable the initializer feature
# please implement the initializer function as below:
# def initializer(context):
#   logger = logging.getLogger()
#   logger.info('initializing')

def handler(event, context):
  logger = logging.getLogger()
  logger.info('hello world:' + bytes.decode(event))
  return 'hello world:' + bytes.decode(event)
  • Optional:EventBridge
    Note You need to activate EventBridge only if the instance to which the Function Compute sink connector belongs is in the China (Hangzhou) or China (Chengdu) region.

Usage notes

  • You can synchronize data from a source topic in a Message Queue for Apache Kafka instance to a function in Function Compute only within the same region. For more information about the limits on connectors, see Limits.
  • If the instance to which the Function Compute sink connector belongs is in the China (Hangzhou) or China (Chengdu) region, the connector is deployed to EventBridge.
    • You can use EventBridge free of charge. For more information, see Billing.
    • When you create a connector, EventBridge automatically creates the following service-linked roles: AliyunServiceRoleForEventBridgeSourceKafka and AliyunServiceRoleForEventBridgeConnectVPC.
      • If these service-linked roles are unavailable, EventBridge automatically creates them so that EventBridge can use these roles to access Message Queue for Apache Kafka and Virtual Private Cloud (VPC).
      • If these service-linked roles are available, EventBridge does not create them again.
      For more information about the service-linked roles, see Service-linked roles.
    • You cannot view the operation logs of tasks that are deployed to EventBridge. After a connector is run, you can check the progress of the synchronization task by viewing the consumption details of the consumer group that subscribes to the source topic. For more information, see View consumption details.

Procedure

To use a Function Compute sink connector to synchronize data from a source topic in a Message Queue for Apache Kafka instance to a function in Function Compute, perform the following steps:

  1. Optional:Allow Function Compute sink connectors to access Function Compute across regions.
    Important If you do not need to use Function Compute sink connectors to access Function Compute across regions, skip this step.

    Enable Internet access for Function Compute sink connectors

  2. Optional:Allow Function Compute sink connectors to access Function Compute across Alibaba Cloud accounts.
    Important If you do not need to use Function Compute sink connectors to access Function Compute across Alibaba Cloud accounts, skip this step.
  3. Optional:Create the topics and consumer group that are required by a Function Compute sink connector.
    Important
    • If you do not need to customize the names of the topics and consumer group, skip this step.
    • Specific topics that are required by a Function Compute sink connector must use the local storage engine. If the major version of your Message Queue for Apache Kafka instance is V0.10.2, you cannot manually create topics that use the local storage engine. In this case, these topics must be automatically created.
    1. Create the topics that are required by a Function Compute sink connector
    2. Create the consumer group that is required by a Function Compute sink connector
  4. Create and deploy a Function Compute sink connector
  5. Verify the result.
    1. Send a test message
    2. View function logs

Enable Internet access for Function Compute sink connectors

If you need to use Function Compute sink connectors to access other Alibaba Cloud services across regions, enable Internet access for Function Compute sink connectors. For more information, see Enable Internet access for a connector.

Create a custom policy.

Create a custom policy to grant access to Function Compute within the Alibaba Cloud account to which you want to synchronize data.

  1. Log on to the RAM console.
  2. In the left-side navigation pane, choose Permissions > Policies.
  3. On the Policies page, click Create Policy.
  4. On the Create Policy page, create a custom policy.
    1. Click the JSON tab, enter the script of the custom policy in the code editor, and then click Next Step.
      Sample script: 
      {
    "Version": "1",
    "Statement": [
        {
            "Action": [
                "fc:InvokeFunction",
                "fc:GetFunction"
            ],
            "Resource": "*",
            "Effect": "Allow"
        }
    ]
}
    2. In the Basic Information section, enter KafkaConnectorFcAccess in the Name field.
    3. Click OK.

Create a RAM role

Create a RAM role within the Alibaba Cloud account to which you want to synchronize data. You cannot select Message Queue for Apache Kafka as the trusted service when you create a RAM role. Therefore, select a supported service as the trusted service first. Then, modify the trust policy of the created RAM role.

  1. In the left-side navigation pane, click RAM Roles.
  2. On the RAM Roles page, click Create RAM Role.
  3. In the Create Role panel, create a RAM role.
    1. Set the Select Trusted Entity parameter to Alibaba Cloud Service and click Next.
    2. Set the Role Type parameter to Normal Service Role. In the RAM Role Name field, enter AliyunKafkaConnectorRole. From the Select Trusted Service drop-down list, select Function Compute. Then, click OK.
  4. On the Roles page, find and click AliyunKafkaConnectorRole.
  5. On the AliyunKafkaConnectorRole page, click the Trust Policy Management tab. On this tab, click Edit Trust Policy.
  6. In the Edit Trust Policy panel, replace fc in the script with alikafka and click OK.
    AliyunKafkaConnectorRole

Grant permissions to the RAM role

Grant the created RAM role the permissions to access Function Compute within the Alibaba Cloud account to which you want to synchronize data.

  1. In the left-side navigation pane, click RAM Roles.
  2. On the Roles page, find AliyunKafkaConnectorRole and click Add Permissions in the Actions column.
  3. In the Add Permissions panel, attach the KafkaConnectorFcAccess policy to the RAM role.
    1. In the Select Policy section, click Custom Policy.
    2. In the Authorization Policy Name column, find and click KafkaConnectorFcAccess.
    3. Click OK.
    4. Click Complete.

Create the topics that are required by a Function Compute sink connector

In the Message Queue for Apache Kafka console, create the following topics that are required by a Function Compute sink connector: task offset topic, task configuration topic, task status topic, dead-letter queue topic, and error data topic. These topics differ in the partition count and storage engine. For more information, see Parameters in the Configure Source Service step.

  1. Log on to the Message Queue for Apache Kafka console.
  2. In the Resource Distribution section of the Overview page, select the region where your instance is deployed.
    Important You must create topics in the region where your application is deployed. When you create a topic, select the region where your Elastic Compute Service (ECS) instance is deployed. A topic cannot be used across regions. For example, if your message producers and consumers run on ECS instances that are deployed in the China (Beijing) region, create topics in the China (Beijing) region.
  3. On the Instances page, click the name of the instance that you want to manage.
  4. In the left-side navigation pane, click Topics.
  5. On the Topics page, click Create Topic.
  6. In the Create Topic panel, configure the parameters and click OK.
    Creates a topic
    Parameter Description Example
    Name The name of the topic. demo
    Description The description of the topic. demo test
    Partitions The number of partitions of the topic. 12
    Storage Engine The storage engine of the topic.

    Message Queue for Apache Kafka supports the following storage engines:

    • Cloud Storage: If you specify this value, the system uses Alibaba Cloud disks for the topic and stores data in three replicas in distributed mode. This storage engine provides the following benefits: low latency, high performance, durability, and high reliability. If you set the Instance Edition parameter to Standard (High Write) when you created the instance, you can specify only Cloud Storage as the value of the Storage Engine parameter.
    • Local Storage: If you specify this value, the system uses the in-sync replicas (ISR) algorithm of open source Apache Kafka and stores data in three replicas in distributed mode.
    		Cloud Storage
    Message Type The message type of the topic.
    • Normal Message: By default, messages of the same key are stored in the same partition in the order in which the messages are sent. When a broker in the cluster fails, the order of the messages may not be preserved in affected partitions. If you set the Storage Engine parameter to Cloud Storage, this parameter is automatically set to Normal Message.
    • Partitionally Ordered Message: By default, messages of the same key are stored in the same partition in the order in which the messages are sent. When a broker in the cluster breaks down, the messages are stored in the same order in the partitions that are affected by the failed broker. The affected partitions cannot store new messages until the partitions are restored. If you set the Storage Engine parameter to Local Storage, this parameter is automatically set to Partitionally Ordered Message.
    		Normal Message
    Log Cleanup Policy The log cleanup policy for the topic.

    If you set the Storage Engine parameter to Local Storage, configure the Log Cleanup Policy parameter.

    Message Queue for Apache Kafka provides the following log cleanup policies:

    • Delete: The default log cleanup policy is used. If sufficient storage space is available in the system, messages are retained based on the maximum retention period. After the storage usage exceeds 85%, the system deletes messages in the order in which the messages are stored. The earliest message that is stored is the first message that is deleted. This helps ensure that the performance of the service is not degraded.
    • Compact: The Apache Kafka log compaction policy is used. If the log compaction policy is used and the keys of different messages are the same, the system retains the most recent message that is stored. This policy applies to scenarios in which the system recovers from a failure, or the cache is reloaded after a system restart. For example, when you use Kafka Connect or Confluent Schema Registry, you must store the information about the system status and configurations in a log-compacted topic.
      Important You can use log-compacted topics only in specific ecosystem components such as Kafka Connect and Confluent Schema Registry. You cannot use the log compaction policy for a topic that is used to send and receive messages in other components. For more information, see Message Queue for Apache Kafka demos.
    		Compact
    Tag The tags that you want to attach to the topic. demo
    After the topic is created, the topic is displayed on the Topics page.

Create the consumer group that is required by a Function Compute sink connector

In the Message Queue for Apache Kafka console, create the consumer group that is required by a Function Compute sink connector. The name of the consumer group must be in the connect-Task name format. For more information, see Parameters in the Configure Source Service step.

  1. Log on to the Message Queue for Apache Kafka console.
  2. In the Resource Distribution section of the Overview page, select the region where your instance is deployed.
  3. On the Instances page, click the name of the instance that you want to manage.
  4. In the left-side navigation pane, click Groups.
  5. On the Groups page, click Create Group.
  6. In the Create Group panel, enter the group name in the Group ID field and the group description in the Description field, attach tags to the group, and then click OK.
    After the group is created, you can view the group on the Groups page.

Create and deploy a Function Compute sink connector

Create and deploy a Function Compute sink connector that synchronizes data from Message Queue for Apache Kafka to Function Compute.

  1. Log on to the Message Queue for Apache Kafka console.
  2. In the Resource Distribution section of the Overview page, select the region where your instance is deployed.
  3. In the left-side navigation pane, click Connectors.
  4. On the Connectors page, select the instance in which the data source topic resides from the Select Instance drop-down list and click Create Connector.
  5. Complete the Create Connector wizard.
    1. In the Configure Basic Information step, set the parameters that are described in the following table and click Next.
      Parameter Description Example
      Name The name of the connector. Specify a connector name based on the following rules:
      • The connector name must be 1 to 48 characters in length. It can contain digits, lowercase letters, and hyphens (-), but cannot start with a hyphen (-).
      • Each connector name must be unique within a Message Queue for Apache Kafka instance.

      The data synchronization task of the connector must use a consumer group that is named in the connect-Task name format. If you have not created such a consumer group, Message Queue for Apache Kafka automatically creates one for you.

      		kafka-fc-sink
      Instance The information about the Message Queue for Apache Kafka instance. By default, the name and ID of the instance are displayed. demo alikafka_post-cn-st21p8vj****
    2. In the Configure Source Service step, select Message Queue for Apache Kafka as the source service, set the parameters that are described in the following table, and then click Next.
      Note If you have created the topics and consumer group in advance, set the Resource Creation Method parameter to Manual and enter the names of the created resources in the fields below. Otherwise, set the Resource Creation Method parameter to Auto.
      Table 1. Parameters in the Configure Source Service step
      Parameter Description Example
      Data Source Topic The name of the source topic from which data is to be synchronized. fc-test-input
      Consumer Thread Concurrency The number of concurrent consumer threads used to synchronize data from the source topic. By default, six concurrent consumer threads are used. Valid values:
      • 1
      • 2
      • 3
      • 6
      • 12
      		 6
      Consumer Offset The offset from which consumption starts. Valid values:
      • Earliest Offset: Consumption starts from the earliest offset.
      • Latest Offset: Consumption starts from the latest offset.
      		Earliest Offset
      VPC ID The ID of the VPC in which the data synchronization task runs. Click Configure Runtime Environment to display the parameter. The default value is the VPC ID that you specified when you deployed the Message Queue for Apache Kafka instance. You do not need to change the value. vpc-bp1xpdnd3l***
      vSwitch ID The ID of the vSwitch in which the data synchronization task runs. Click Configure Runtime Environment to display the parameter. The vSwitch must be deployed in the same VPC as the Message Queue for Apache Kafka instance. The default value is the vSwitch ID that you specified when you deployed the Message Queue for Apache Kafka instance. vsw-bp1d2jgg81***
      Failure Handling Policy Specifies whether to retain the subscription to the partition in which an error occurs after the relevant message fails to be sent. Click Configure Runtime Environment to display the parameter. Valid values:
      • Continue Subscription: retains the subscription to the partition in which an error occurs and returns the logs.
      • Stop Subscription: stops the subscription to the partition in which an error occurs and returns the logs.
      Note
      		Continue Subscription
      Resource Creation Method The method used to create the topics and consumer group that are required by the Function Compute sink connector. Click Configure Runtime Environment to display the parameter. Valid values:
      • Auto
      • Manual
      		 Auto
      Connector Consumer Group The consumer group that is used by the data synchronization task of the connector. Click Configure Runtime Environment to display the parameter. The name of this consumer group must be in the connect-Task name format. connect-kafka-fc-sink
      Task Offset Topic The topic that is used to store consumer offsets. Click Configure Runtime Environment to display the parameter.
      • Topic: We recommend that you start the topic name with connect-offset.
      • Partitions: The number of partitions in the topic must be greater than 1.
      • Storage Engine: The storage engine of the topic must be set to Local Storage.
      • cleanup.policy: The log cleanup policy for the topic must be set to Compact.
      		connect-offset-kafka-fc-sink
      Task Configuration Topic The topic that is used to store task configurations. Click Configure Runtime Environment to display the parameter.
      • Topic: We recommend that you start the topic name with connect-config.
      • Partitions: The topic can contain only one partition.
      • Storage Engine: The storage engine of the topic must be set to Local Storage.
      • cleanup.policy: The log cleanup policy for the topic must be set to Compact.
      		connect-config-kafka-fc-sink
      Task Status Topic The topic that is used to store the task status. Click Configure Runtime Environment to display the parameter.
      • Topic: We recommend that you start the topic name with connect-status.
      • Partitions: We recommend that you set the number of partitions in the topic to 6.
      • Storage Engine: The storage engine of the topic must be set to Local Storage.
      • cleanup.policy: The log cleanup policy for the topic must be set to Compact.
      		connect-status-kafka-fc-sink
      Dead-letter Queue Topic The topic that is used to store the error data of the Kafka Connect framework. Click Configure Runtime Environment to display the parameter. To save topic resources, you can create a topic and use the topic as both the dead-letter queue topic and the error data topic.
      • Topic: We recommend that you start the topic name with connect-error.
      • Partitions: We recommend that you set the number of partitions in the topic to 6.
      • Storage Engine: The storage engine of the topic can be set to Local Storage or Cloud Storage.
      		connect-error-kafka-fc-sink
      Error Data Topic The topic that is used to store the error data of the connector. Click Configure Runtime Environment to display the parameter. To save topic resources, you can create a topic and use the topic as both the dead-letter queue topic and the error data topic.
      • Topic: We recommend that you start the topic name with connect-error.
      • Partitions: We recommend that you set the number of partitions in the topic to 6.
      • Storage Engine: The storage engine of the topic can be set to Local Storage or Cloud Storage.
      		connect-error-kafka-fc-sink
    3. In the Configure Destination Service step, select Function Compute as the destination service, set the parameters that are described in the following table, and then click Create.
      Note If the instance to which the Function Compute sink connector belongs is in the China (Hangzhou) or China (Chengdu) region, the Service Authorization message appears when you select Function Compute as the destination service. The following service-linked roles are automatically created if you click OK: AliyunServiceRoleForEventBridgeSourceKafka and AliyunServiceRoleForEventBridgeSourceKafka. Click OK in the Service Authorization message, set the parameters that are described in the following table, and then click Create. If the service-linked roles have been created, the Service Authorization message does not appear.
      Parameter Description Example
      Cross-account/Cross-region Specifies whether the Function Compute sink connector synchronizes data to Function Compute across Alibaba Cloud accounts or regions. By default, this parameter is set to No. Valid values:
      • No: The Function Compute sink connector synchronizes data to Function Compute within the same region and the same Alibaba Cloud account.
      • Yes: The Function Compute sink connector synchronizes data to Function Compute across regions but within the same Alibaba Cloud account, within the same region but across Alibaba Cloud accounts, or across regions and Alibaba Cloud accounts.
      		No
      Region The region in which Function Compute is activated. By default, the region in which the Function Compute sink connector resides is selected. To synchronize data across regions, enable Internet access for the connector and select the destination region. For more information, see Enable Internet access for Function Compute sink connectors.
      Important The Region parameter is displayed only if you set the Cross-account/Cross-region parameter to Yes.
      		cn-hangzhou
      Service Endpoint The endpoint of Function Compute. In the Function Compute console, you can view the endpoints of Function Compute in the Common Info section of the Overview page.
      • Internal endpoint: We recommend that you use the internal endpoint for lower latency. The internal endpoint can be used if the Message Queue for Apache Kafka instance and Function Compute are in the same region.
      • Public endpoint: We recommend that you do not use the public endpoint due to a higher latency. The public endpoint can be used if the Message Queue for Apache Kafka instance and Function Compute are in different regions. To use the public endpoint, you must enable Internet access for the connector. For more information, see Enable Internet access for Function Compute sink connectors.
      Important The Service Endpoint parameter is displayed only if you set the Cross-account/Cross-region parameter to Yes.
      		http://188***.cn-hangzhou.fc.aliyuncs.com
      Alibaba Cloud Account The ID of the Alibaba Cloud account that is used to log on to Function Compute. In the Function Compute console, you can view the ID of the Alibaba Cloud account in the Common Info section of the Overview page.
      Important The Alibaba Cloud Account parameter is displayed only if you set the Cross-account/Cross-region parameter to Yes.
      		188***
      RAM Role Name The name of the RAM role that Message Queue for Apache Kafka assumes to access Function Compute.
      Important The RAM Role Name parameter is displayed only if you set the Cross-account/Cross-region parameter to Yes.
      		AliyunKafkaConnectorRole
      Service Name The name of the service in Function Compute. guide-hello_world
      Function Name The name of the function in the service in Function Compute. hello_world
      Version or Alias The version or alias of the service in Function Compute.
      Important
      • You must set this parameter to Specified Version or Specified Alias if you set the Cross-account/Cross-region parameter to No.
      • You must specify a service version or alias if you set the Cross-account/Cross-region parameter to Yes.
      		LATEST
      Service Version The version of the service in Function Compute.
      Important The Service Version parameter is displayed only if you set the Cross-account/Cross-region parameter to No and the Version or Alias parameter to Specified Version.
      		LATEST
      Service Alias The alias of the service in Function Compute.
      Important The Service Alias parameter is displayed only if you set the Cross-account/Cross-region parameter to No and the Version or Alias parameter to Specified Alias.
      		jy
      Transmission Mode The mode in which messages are sent. Valid values:
      • Asynchronous: recommended.
      • Synchronous: not recommended. In synchronous mode, if Function Compute processes messages for a long period of time, Message Queue for Apache Kafka waits for Function Compute to complete the processing. If a batch of messages fail to be processed within 5 minutes, the Message Queue for Apache Kafka client rebalances the traffic.
      		Asynchronous
      Data Size The maximum number of messages that can be sent at a time. Default value: 20. The connector aggregates messages to be concurrently sent based on the maximum number of messages and the maximum message size allowed in a request. The size of an aggregate message cannot exceed 6 MB in synchronous mode and 128 KB in asynchronous mode. For example, messages are sent in asynchronous mode, and up to 20 messages can be sent at a time. You want to send 18 messages, among which 17 messages have a total size of 127 KB, and one message is 200 KB in size. In this case, the connector aggregates the 17 messages into a single batch and sends this batch first, and then sends the remaining message whose size is more than 128 KB.
      Note If you set the key parameter to null when you send a message, the request does not contain the key parameter. If you set the value parameter to null, the request does not contain the value parameter.
      • If the size of messages in a batch does not exceed the maximum message size allowed in a request, the request contains all content of the messages. Sample request:
        [
    {
        "key":"this is the message's key2",
        "offset":8,
        "overflowFlag":false,
        "partition":4,
        "timestamp":1603785325438,
        "topic":"Test",
        "value":"this is the message's value2",
        "valueSize":28
    },
    {
        "key":"this is the message's key9",
        "offset":9,
        "overflowFlag":false,
        "partition":4,
        "timestamp":1603785325440,
        "topic":"Test",
        "value":"this is the message's value9",
        "valueSize":28
    },
    {
        "key":"this is the message's key12",
        "offset":10,
        "overflowFlag":false,
        "partition":4,
        "timestamp":1603785325442,
        "topic":"Test",
        "value":"this is the message's value12",
        "valueSize":29
    },
    {
        "key":"this is the message's key38",
        "offset":11,
        "overflowFlag":false,
        "partition":4,
        "timestamp":1603785325464,
        "topic":"Test",
        "value":"this is the message's value38",
        "valueSize":29
    }
]
      • If the size of a single message exceeds the maximum message size allowed in a request, the request does not contain the content of the message. Sample request:
        [
    {
        "key":"123",
        "offset":4,
        "overflowFlag":true,
        "partition":0,
        "timestamp":1603779578478,
        "topic":"Test",
        "value":"1",
        "valueSize":272687
    }
]
        Note To obtain the content of the message, you must pull the message based on its offset.
      		50
      Retries The maximum number of retries allowed after a message fails to be sent. Default value: 2. Valid values: 1 to 3. In specific cases when a message fails to be sent, retries are not supported. The following rules describe the types of error codes and whether retries are supported. For more information, see Error codes.
      • 4XX: Retries are not supported except in the case when 429 is returned.
      • 5XX: Retries are supported.
      Note
      • The connector calls the InvokeFunction operation to send messages to Function Compute.
      • If a message still fails to be sent to Function Compute after the maximum number of retries, the message is sent to the dead-letter queue topic. Messages in the dead-letter queue topic cannot be synchronized to Function Compute by using the connector. We recommend that you configure an alert rule for the topic to monitor the topic resources in real time. This way, you can troubleshoot issues at the earliest opportunity.
      		2
      After the connector is created, you can view the connector on the Connectors page.
  6. Go to the Connectors page, find the connector that you created, and then click Deploy in the Actions column.
    To configure Function Compute resources, choose More > Configure Function in the Actions column to go to the Function Compute console and complete the configuration.

Send a test message

After you deploy the Function Compute sink connector, you can send a message to the source topic in the Message Queue for Apache Kafka instance to test whether the message can be synchronized to Function Compute.

  1. On the Connectors page, find the connector that you want to use and click Test in the Actions column.
  2. In the Send Message panel, configure the required parameters to send a test message.
    • Set the Method of Sending parameter to Console.
      1. In the Message Key field, enter the key of the message. For example, you can enter demo as the key of the message.
      2. In the Message Content field, enter the content of the message. For example, you can enter {"key": "test"} as the content of the message.
      3. Configure the Send to Specified Partition parameter to specify whether to send the message to a specific partition.
        • If you want to send the message to a specific partition, click Yes and enter the partition ID in the Partition ID field. For example, you can enter 0 as the partition ID. For information about how to query partition IDs, see View partition status.
        • If you do not want to send the message to a specific partition, click No.
    • Set the Method of Sending parameter to Docker and run the docker commands that are provided in the Run the Docker container to produce a sample message section to send a test message.
    • Set the Method of Sending parameter to SDK and click the link to the topic that describes how to obtain and use the SDK that you want to use. Then, use the SDK to send and consume a test message. Message Queue for Apache Kafka provides topics that describe how to use SDKs for different programming languages based on different connection types.

View function logs

After you send a message to the source topic in the Message Queue for Apache Kafka instance, you can view the function logs to check whether the message is received. For more information, see Configure the logging feature.

If the test message that you sent appears in the logs as shown in the following figure, the data synchronization task is successful.

fc LOG