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使用Python SDK通过消费组消费日志

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通过消费组（ConsumerGroup）消费日志有显著优点，您无需关注日志服务的实现细节和消费者之间的负载均衡、Failover等，只需要专注于业务逻辑即可。本文通过Python代码介绍如何使用消费组消费日志。

工作流程

image

一个Logstore中包含多个Shard，通过消费组消费数据就是将Shard分配给一个消费组下面的消费者，分配方式遵循以下原则。

  • 在一个消费组中，一个Shard只会分配到一个消费者。

  • 在一个消费组中，一个消费者可以被分配多个Shard。

新的消费者加入消费组后，这个消费组下面的Shard从属关系会调整，以实现消费的负载均衡，但是仍遵循上述分配原则。

说明

通过消费组消费，程序发生故障时，会默认保存Checkpoint。在程序故障恢复时，能够从断点处继续消费，从而保证数据不会被重复消费。

前提条件

  • 已开通日志服务。更多信息，请参见开通日志服务。

  • 已创建RAM用户并完成授权。具体操作，请参见创建RAM用户并完成授权。

  • 已配置环境变量ALIBABA_CLOUD_ACCESS_KEY_ID和ALIBABA_CLOUD_ACCESS_KEY_SECRET。具体操作，请参见在Linux、macOS和Windows系统配置环境变量。

    重要

    • 阿里云账号的AccessKey拥有所有API的访问权限，建议您使用RAM用户的AccessKey进行API访问或日常运维。

    • 强烈建议不要把AccessKey ID和AccessKey Secret保存到工程代码里，否则可能导致AccessKey泄露，威胁您账号下所有资源的安全。

注意事项

本示例以华东1（杭州）的公网Endpoint为例，其公网Endpoint为https://cn-hangzhou.log.aliyuncs.com。如果您通过与Project同地域的其他阿里云产品访问日志服务，请使用内网Endpointhttps://cn-hangzhou-intranet.log.aliyuncs.com。关于日志服务支持的地域与Endpoint的对应关系，请参见服务入口。

代码示例

以下代码用于创建Logstore、为Logstore写入日志、创建消费组并消费日志。

import os
import time

from aliyun.log.consumer import *
from aliyun.log import *
from threading import RLock


class SampleConsumer(ConsumerProcessorBase):
    shard_id = -1
    last_check_time = 0
    log_results = []
    lock = RLock()

    def initialize(self, shard):
        self.shard_id = shard

    def process(self, log_groups, check_point_tracker):
        for log_group in log_groups.LogGroups:
            items = []
            for log in log_group.Logs:
                item = dict()
                item['time'] = log.Time
                for content in log.Contents:
                    item[content.Key] = content.Value
                items.append(item)
            log_items = dict()
            log_items['topic'] = log_group.Topic
            log_items['source'] = log_group.Source
            log_items['logs'] = items

            with SampleConsumer.lock:
                SampleConsumer.log_results.append(log_items)
                print(log_items)

        current_time = time.time()
        if current_time - self.last_check_time > 3:
            try:
                self.last_check_time = current_time
                check_point_tracker.save_check_point(True)
            except Exception:
                import traceback
                traceback.print_exc()
        else:
            try:
                check_point_tracker.save_check_point(False)
            except Exception:
                import traceback
                traceback.print_exc()

        # None means succesful process
        # if need to roll-back to previous checkpoint，return check_point_tracker.get_check_point()
        return None

    def shutdown(self, check_point_tracker):
        try:
            check_point_tracker.save_check_point(True)
        except Exception:
            import traceback
            traceback.print_exc()


test_item_count = 20

# 为Logstore写入日志。
def _prepare_data(client, project, logstore):
    topic = 'python-ide-test'
    source = ''

    for i in range(0, test_item_count):
        logitemList = []  # LogItem list

        contents = [
            ('user', 'magic_user_' + str(i)),
            ('avg', 'magic_age_' + str(i))
        ]
        logItem = LogItem()
        logItem.set_time(int(time.time()))
        logItem.set_contents(contents)

        logitemList.append(logItem)
        # 将日志写入Logstore。
        request = PutLogsRequest(project, logstore, topic, source, logitemList)

        response = client.put_logs(request)
        print("successfully put logs in logstore")


def sleep_until(seconds, exit_condition=None, expect_error=False):
    if not exit_condition:
        time.sleep(seconds)
        return

    s = time.time()
    while time.time() - s < seconds:
        try:
            if exit_condition():
                break
        except Exception:
            if expect_error:
                continue
        time.sleep(1)


def sample_consumer_group():
    # 日志服务的服务接入点。此处以杭州为例，其它地域请根据实际情况填写。
    endpoint = os.environ.get('ALIYUN_LOG_SAMPLE_ENDPOINT', 'cn-hangzhou.log.aliyuncs.com')

    # 本示例从环境变量中获取AccessKey ID和AccessKey Secret。
    accessKeyId = os.environ.get('ALIBABA_CLOUD_ACCESS_KEY_ID', '')
    accessKey = os.environ.get('ALIBABA_CLOUD_ACCESS_KEY_SECRET', '')

    # Project名称。本示例中，SDK不会创建Project，您需要在运行代码前创建该Project。
    project = os.environ.get('ALIYUN_LOG_SAMPLE_PROJECT', 'ali-test-project-python')

    # Logstore名称。本示例中，SDK会自动创建该Logstore，您无需提前创建该Logstore。
    logstore = 'ali-test-logstore'

    # 消费组名称。您无需提前创建，SDK会自动创建该消费组。
    consumer_group = 'consumer-group-1'
    consumer_name1 = "consumer-group-1-A"
    consumer_name2 = "consumer-group-1-B"
    token = ""

    if not logstore:
        logstore = 'consumer_group_test_' + str(time.time()).replace('.', '_')

    assert endpoint and accessKeyId and accessKey and project, ValueError("endpoint/access_id/key and "
                                                                          "project cannot be empty")

    # 创建Logstore。
    client = LogClient(endpoint, accessKeyId, accessKey, token)
    ret = client.create_logstore(project, logstore, 2, 4)
    print("successfully create logstore")

    time.sleep(60)
    SampleConsumer.log_results = []

    try:
        # 为Logstore写入日志。
        _prepare_data(client, project, logstore)

        # 在消费组中创建2个消费者消费数据。
        option1 = LogHubConfig(endpoint, accessKeyId, accessKey, project, logstore, consumer_group,
                               consumer_name1, cursor_position=CursorPosition.BEGIN_CURSOR, heartbeat_interval=6,
                               data_fetch_interval=1)
        option2 = LogHubConfig(endpoint, accessKeyId, accessKey, project, logstore, consumer_group,
                               consumer_name2, cursor_position=CursorPosition.BEGIN_CURSOR, heartbeat_interval=6,
                               data_fetch_interval=1)

        print("*** start to consume data...")
        client_worker1 = ConsumerWorker(SampleConsumer, consumer_option=option1)
        client_worker1.start()
        client_worker2 = ConsumerWorker(SampleConsumer, consumer_option=option2)
        client_worker2.start()

        sleep_until(300, lambda: len(SampleConsumer.log_results) >= test_item_count)

        print("*** consumer group status ***")
        ret = client.list_consumer_group(project, logstore)
        print("successfully list consumergroup")

        for c in ret.get_consumer_groups():
            ret = client.get_check_point_fixed(project, logstore, c.get_consumer_group_name())
            print("successfully get checkpoint fixed")

        print("*** stopping workers")
        client_worker1.shutdown()
        client_worker2.shutdown()

    finally:
        # clean-up
        # ret = client.delete_logstore(project, logstore)
        ret = client.list_logstore(project, logstore)
        print("successfully list logstore")

    # validate
    ret = str(SampleConsumer.log_results)
    print("*** get content:")
    print(ret)

    assert 'magic_user_0' in ret and 'magic_age_0' in ret \
           and 'magic_user_' + str(test_item_count-1) in ret \
           and 'magic_age_' + str(test_item_count-1) in ret


if __name__ == '__main__':
    sample_consumer_group()

预期结果如下：

successfully create logstore
successfully put logs in logstore
successfully put logs in logstore
successfully put logs in logstore
successfully put logs in logstore
successfully put logs in logstore
......
*** start to consume data...
{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123452, 'user': 'magic_user_0', 'avg': 'magic_age_0'}]}
{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_1', 'avg': 'magic_age_1'}]}
{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_3', 'avg': 'magic_age_3'}]}
{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_5', 'avg': 'magic_age_5'}]}
{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_6', 'avg': 'magic_age_6'}]}
......
*** consumer group status ***
successfully list consumergroup
successfully get checkpoint fixed
*** stopping workers
successfully list logstore
*** get content:
[{'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123452, 'user': 'magic_user_0', 'avg': 'magic_age_0'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_1', 'avg': 'magic_age_1'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_3', 'avg': 'magic_age_3'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_5', 'avg': 'magic_age_5'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_6', 'avg': 'magic_age_6'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_8', 'avg': 'magic_age_8'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_9', 'avg': 'magic_age_9'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_2', 'avg': 'magic_age_2'}]}, {'topic': 'python-ide-test', 'source': '47.100.XX.XX', 'logs': [{'time': 1672123453, 'user': 'magic_user_11', 'avg': 'magic_age_11'}]}, ......}]

相关文档

  • 阿里云OpenAPI开发者门户提供调试、SDK、示例和配套文档。通过OpenAPI，您无需手动封装请求和签名操作，就可以快速对日志服务API进行调试。更多信息，请参见OpenAPI开发者门户。

  • 为满足越来越多的自动化日志服务配置需求，日志服务提供命令行工具CLI（Command Line Interface）。更多信息，请参见日志服务命令行工具CLI。

  • 更多示例代码，请参见Aliyun Log Python SDK on GitHub。

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