文件 AWS 開發套件範例 GitHub 儲存庫中有更多可用的 [AWS SDK 範例](https://github.com/awsdocs/aws-doc-sdk-examples)。

本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

# 使用 SDK for Python (Boto3) 的 CloudWatch Logs 範例
<a name="python_3_cloudwatch-logs_code_examples"></a>

下列程式碼範例示範如何使用 適用於 Python (Boto3) 的 AWS SDK 搭配 CloudWatch Logs 執行動作和實作常見案例。

*Actions* 是大型程式的程式碼摘錄，必須在內容中執行。雖然動作會告訴您如何呼叫個別服務函數，但您可以在其相關情境中查看內容中的動作。

*案例*是向您展示如何呼叫服務中的多個函數或與其他 AWS 服務組合來完成特定任務的程式碼範例。

每個範例均包含完整原始碼的連結，您可在連結中找到如何設定和執行內容中程式碼的相關指示。

**Topics**
+ [動作](#actions)
+ [案例](#scenarios)

## 動作
<a name="actions"></a>

### `GetQueryResults`
<a name="cloudwatch-logs_GetQueryResults_python_3_topic"></a>

以下程式碼範例顯示如何使用 `GetQueryResults`。

**適用於 Python 的 SDK (Boto3)**  
 GitHub 上提供更多範例。尋找完整範例，並了解如何在 [AWS 程式碼範例儲存庫](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/cloudwatch-logs#code-examples)中設定和執行。

```
    def _wait_for_query_results(self, client, query_id):
        """
        Waits for the query to complete and retrieves the results.

        :param query_id: The ID of the initiated query.
        :type query_id: str
        :return: A list containing the results of the query.
        :rtype: list
        """
        while True:
            time.sleep(1)
            results = client.get_query_results(queryId=query_id)
            if results["status"] in [
                "Complete",
                "Failed",
                "Cancelled",
                "Timeout",
                "Unknown",
            ]:
                return results.get("results", [])
```
+  如需 API 詳細資訊，請參閱《AWS SDK for Python (Boto3) API 參考》**中的 [GetQueryResults](https://docs.aws.amazon.com/goto/boto3/logs-2014-03-28/GetQueryResults)。

### `StartLiveTail`
<a name="cloudwatch-logs_StartLiveTail_python_3_topic"></a>

以下程式碼範例顯示如何使用 `StartLiveTail`。

**適用於 Python 的 SDK (Boto3)**  
包括必需的檔案。  

```
import boto3 
import time
from datetime import datetime
```
開始 Live Tail 工作階段。  

```
    # Initialize the client
    client = boto3.client('logs')

    start_time = time.time()

    try:
        response = client.start_live_tail(
            logGroupIdentifiers=log_group_identifiers,
            logStreamNames=log_streams,
            logEventFilterPattern=filter_pattern
        )
        event_stream = response['responseStream']
        # Handle the events streamed back in the response
        for event in event_stream:
            # Set a timeout to close the stream.
            # This will end the Live Tail session.
            if (time.time() - start_time >= 10):
                event_stream.close()
                break
            # Handle when session is started
            if 'sessionStart' in event:
                session_start_event = event['sessionStart']
                print(session_start_event)
            # Handle when log event is given in a session update
            elif 'sessionUpdate' in event:
                log_events = event['sessionUpdate']['sessionResults']
                for log_event in log_events:
                    print('[{date}] {log}'.format(date=datetime.fromtimestamp(log_event['timestamp']/1000),log=log_event['message']))
            else:
                # On-stream exceptions are captured here
                raise RuntimeError(str(event))
    except Exception as e:
        print(e)
```
+  如需 API 詳細資訊，請參閱《AWS SDK for Python (Boto3) API 參考》**中的 [StartLiveTail](https://docs.aws.amazon.com/goto/boto3/logs-2014-03-28/StartLiveTail)。

### `StartQuery`
<a name="cloudwatch-logs_StartQuery_python_3_topic"></a>

以下程式碼範例顯示如何使用 `StartQuery`。

**適用於 Python 的 SDK (Boto3)**  
 GitHub 上提供更多範例。尋找完整範例，並了解如何在 [AWS 程式碼範例儲存庫](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/cloudwatch-logs#code-examples)中設定和執行。

```
    def perform_query(self, date_range):
        """
        Performs the actual CloudWatch log query.

        :param date_range: A tuple representing the start and end datetime for the query.
        :type date_range: tuple
        :return: A list containing the query results.
        :rtype: list
        """
        client = boto3.client("logs")
        try:
            try:
                start_time = round(
                    self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[0])
                )
                end_time = round(
                    self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[1])
                )
                response = client.start_query(
                    logGroupName=self.log_group,
                    startTime=start_time,
                    endTime=end_time,
                    queryString=self.query_string,
                    limit=self.limit,
                )
                query_id = response["queryId"]
            except client.exceptions.ResourceNotFoundException as e:
                raise DateOutOfBoundsError(f"Resource not found: {e}")
            while True:
                time.sleep(1)
                results = client.get_query_results(queryId=query_id)
                if results["status"] in [
                    "Complete",
                    "Failed",
                    "Cancelled",
                    "Timeout",
                    "Unknown",
                ]:
                    return results.get("results", [])
        except DateOutOfBoundsError:
            return []

    def _initiate_query(self, client, date_range, max_logs):
        """
        Initiates the CloudWatch logs query.

        :param date_range: A tuple representing the start and end datetime for the query.
        :type date_range: tuple
        :param max_logs: The maximum number of logs to retrieve.
        :type max_logs: int
        :return: The query ID as a string.
        :rtype: str
        """
        try:
            start_time = round(
                self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[0])
            )
            end_time = round(
                self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[1])
            )
            response = client.start_query(
                logGroupName=self.log_group,
                startTime=start_time,
                endTime=end_time,
                queryString=self.query_string,
                limit=max_logs,
            )
            return response["queryId"]
        except client.exceptions.ResourceNotFoundException as e:
            raise DateOutOfBoundsError(f"Resource not found: {e}")
```
+  如需 API 詳細資訊，請參閱《AWS SDK for Python (Boto3) API 參考**》中的 [StartQuery](https://docs.aws.amazon.com/goto/boto3/logs-2014-03-28/StartQuery)。

## 案例
<a name="scenarios"></a>

### 執行大型查詢
<a name="cloudwatch-logs_Scenario_BigQuery_python_3_topic"></a>

下列程式碼範例示範如何使用 CloudWatch Logs 查詢超過 10,000 筆記錄。

**適用於 Python 的 SDK (Boto3)**  
 GitHub 上提供更多範例。尋找完整範例，並了解如何在 [AWS 程式碼範例儲存庫](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/cloudwatch-logs/scenarios/large-query#code-examples)中設定和執行。
此檔案會調用範例模組，以用於管理超過 10,000 筆結果的 CloudWatch 查詢。  

```
import logging
import os
import sys

import boto3
from botocore.config import Config

from cloudwatch_query import CloudWatchQuery
from date_utilities import DateUtilities

# Configure logging at the module level.
logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s - %(levelname)s - %(filename)s:%(lineno)d - %(message)s",
)

DEFAULT_QUERY_LOG_GROUP = "/workflows/cloudwatch-logs/large-query"


class CloudWatchLogsQueryRunner:
    def __init__(self):
        """
        Initializes the CloudWatchLogsQueryRunner class by setting up date utilities
        and creating a CloudWatch Logs client with retry configuration.
        """
        self.date_utilities = DateUtilities()
        self.cloudwatch_logs_client = self.create_cloudwatch_logs_client()

    def create_cloudwatch_logs_client(self):
        """
        Creates and returns a CloudWatch Logs client with a specified retry configuration.

        :return: A CloudWatch Logs client instance.
        :rtype: boto3.client
        """
        try:
            return boto3.client("logs", config=Config(retries={"max_attempts": 10}))
        except Exception as e:
            logging.error(f"Failed to create CloudWatch Logs client: {e}")
            sys.exit(1)

    def fetch_environment_variables(self):
        """
        Fetches and validates required environment variables for query start and end dates.
        Fetches the environment variable for log group, returning the default value if it
        does not exist.

        :return: Tuple of query start date and end date as integers and the log group.
        :rtype: tuple
        :raises SystemExit: If required environment variables are missing or invalid.
        """
        try:
            query_start_date = int(os.environ["QUERY_START_DATE"])
            query_end_date = int(os.environ["QUERY_END_DATE"])
        except KeyError:
            logging.error(
                "Both QUERY_START_DATE and QUERY_END_DATE environment variables are required."
            )
            sys.exit(1)
        except ValueError as e:
            logging.error(f"Error parsing date environment variables: {e}")
            sys.exit(1)
        
        try:
            log_group = os.environ["QUERY_LOG_GROUP"]
        except KeyError:
            logging.warning("No QUERY_LOG_GROUP environment variable, using default value")
            log_group = DEFAULT_QUERY_LOG_GROUP

        return query_start_date, query_end_date, log_group

    def convert_dates_to_iso8601(self, start_date, end_date):
        """
        Converts UNIX timestamp dates to ISO 8601 format using DateUtilities.

        :param start_date: The start date in UNIX timestamp.
        :type start_date: int
        :param end_date: The end date in UNIX timestamp.
        :type end_date: int
        :return: Start and end dates in ISO 8601 format.
        :rtype: tuple
        """
        start_date_iso8601 = self.date_utilities.convert_unix_timestamp_to_iso8601(
            start_date
        )
        end_date_iso8601 = self.date_utilities.convert_unix_timestamp_to_iso8601(
            end_date
        )
        return start_date_iso8601, end_date_iso8601

    def execute_query(
        self,
        start_date_iso8601,
        end_date_iso8601,
        log_group="/workflows/cloudwatch-logs/large-query",
        query="fields @timestamp, @message | sort @timestamp asc"
    ):
        """
        Creates a CloudWatchQuery instance and executes the query with provided date range.

        :param start_date_iso8601: The start date in ISO 8601 format.
        :type start_date_iso8601: str
        :param end_date_iso8601: The end date in ISO 8601 format.
        :type end_date_iso8601: str
        :param log_group: Log group to search: "/workflows/cloudwatch-logs/large-query"
        :type log_group: str
        :param query: Query string to pass to the CloudWatchQuery instance
        :type query: str
        """
        cloudwatch_query = CloudWatchQuery(
            log_group=log_group,
            query_string=query
        )
        cloudwatch_query.query_logs((start_date_iso8601, end_date_iso8601))
        logging.info("Query executed successfully.")
        logging.info(
            f"Queries completed in {cloudwatch_query.query_duration} seconds. Total logs found: {len(cloudwatch_query.query_results)}"
        )


def main():
    """
    Main function to start a recursive CloudWatch logs query.
    Fetches required environment variables, converts dates, and executes the query.
    """
    logging.info("Starting a recursive CloudWatch logs query...")
    runner = CloudWatchLogsQueryRunner()
    query_start_date, query_end_date, log_group = runner.fetch_environment_variables()
    start_date_iso8601 = DateUtilities.convert_unix_timestamp_to_iso8601(
        query_start_date
    )
    end_date_iso8601 = DateUtilities.convert_unix_timestamp_to_iso8601(query_end_date)
    runner.execute_query(start_date_iso8601, end_date_iso8601, log_group=log_group)


if __name__ == "__main__":
    main()
```
此模組會處理超過 10,000 筆結果的 CloudWatch 查詢。  

```
import logging
import time
from datetime import datetime
import threading
import boto3

from date_utilities import DateUtilities

DEFAULT_QUERY = "fields @timestamp, @message | sort @timestamp asc"
DEFAULT_LOG_GROUP = "/workflows/cloudwatch-logs/large-query"

class DateOutOfBoundsError(Exception):
    """Exception raised when the date range for a query is out of bounds."""

    pass


class CloudWatchQuery:
    """
    A class to query AWS CloudWatch logs within a specified date range.

    :vartype date_range: tuple
    :ivar limit: Maximum number of log entries to return.
    :vartype limit: int
    :log_group str: Name of the log group to query
    :query_string str: query
    """

    def __init__(self, log_group: str = DEFAULT_LOG_GROUP, query_string: str=DEFAULT_QUERY) -> None:
        self.lock = threading.Lock()
        self.log_group = log_group
        self.query_string = query_string
        self.query_results = []
        self.query_duration = None
        self.datetime_format = "%Y-%m-%d %H:%M:%S.%f"
        self.date_utilities = DateUtilities()
        self.limit = 10000

    def query_logs(self, date_range):
        """
        Executes a CloudWatch logs query for a specified date range and calculates the execution time of the query.

        :return: A batch of logs retrieved from the CloudWatch logs query.
        :rtype: list
        """
        start_time = datetime.now()

        start_date, end_date = self.date_utilities.normalize_date_range_format(
            date_range, from_format="unix_timestamp", to_format="datetime"
        )

        logging.info(
            f"Original query:"
            f"\n       START:     {start_date}"
            f"\n       END:       {end_date}"
            f"\n       LOG GROUP: {self.log_group}"
        )
        self.recursive_query((start_date, end_date))
        end_time = datetime.now()
        self.query_duration = (end_time - start_time).total_seconds()

    def recursive_query(self, date_range):
        """
        Processes logs within a given date range, fetching batches of logs recursively if necessary.

        :param date_range: The date range to fetch logs for, specified as a tuple (start_timestamp, end_timestamp).
        :type date_range: tuple
        :return: None if the recursive fetching is continued or stops when the final batch of logs is processed.
                 Although it doesn't explicitly return the query results, this method accumulates all fetched logs
                 in the `self.query_results` attribute.
        :rtype: None
        """
        batch_of_logs = self.perform_query(date_range)
        # Add the batch to the accumulated logs
        with self.lock:
            self.query_results.extend(batch_of_logs)
        if len(batch_of_logs) == self.limit:
            logging.info(f"Fetched {self.limit}, checking for more...")
            most_recent_log = self.find_most_recent_log(batch_of_logs)
            most_recent_log_timestamp = next(
                item["value"]
                for item in most_recent_log
                if item["field"] == "@timestamp"
            )
            new_range = (most_recent_log_timestamp, date_range[1])
            midpoint = self.date_utilities.find_middle_time(new_range)

            first_half_thread = threading.Thread(
                target=self.recursive_query,
                args=((most_recent_log_timestamp, midpoint),),
            )
            second_half_thread = threading.Thread(
                target=self.recursive_query, args=((midpoint, date_range[1]),)
            )

            first_half_thread.start()
            second_half_thread.start()

            first_half_thread.join()
            second_half_thread.join()

    def find_most_recent_log(self, logs):
        """
        Search a list of log items and return most recent log entry.
        :param logs: A list of logs to analyze.
        :return: log
        :type :return List containing log item details
        """
        most_recent_log = None
        most_recent_date = "1970-01-01 00:00:00.000"

        for log in logs:
            for item in log:
                if item["field"] == "@timestamp":
                    logging.debug(f"Compared: {item['value']} to {most_recent_date}")
                    if (
                        self.date_utilities.compare_dates(
                            item["value"], most_recent_date
                        )
                        == item["value"]
                    ):
                        logging.debug(f"New most recent: {item['value']}")
                        most_recent_date = item["value"]
                        most_recent_log = log
        logging.info(f"Most recent log date of batch: {most_recent_date}")
        return most_recent_log

    def perform_query(self, date_range):
        """
        Performs the actual CloudWatch log query.

        :param date_range: A tuple representing the start and end datetime for the query.
        :type date_range: tuple
        :return: A list containing the query results.
        :rtype: list
        """
        client = boto3.client("logs")
        try:
            try:
                start_time = round(
                    self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[0])
                )
                end_time = round(
                    self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[1])
                )
                response = client.start_query(
                    logGroupName=self.log_group,
                    startTime=start_time,
                    endTime=end_time,
                    queryString=self.query_string,
                    limit=self.limit,
                )
                query_id = response["queryId"]
            except client.exceptions.ResourceNotFoundException as e:
                raise DateOutOfBoundsError(f"Resource not found: {e}")
            while True:
                time.sleep(1)
                results = client.get_query_results(queryId=query_id)
                if results["status"] in [
                    "Complete",
                    "Failed",
                    "Cancelled",
                    "Timeout",
                    "Unknown",
                ]:
                    return results.get("results", [])
        except DateOutOfBoundsError:
            return []

    def _initiate_query(self, client, date_range, max_logs):
        """
        Initiates the CloudWatch logs query.

        :param date_range: A tuple representing the start and end datetime for the query.
        :type date_range: tuple
        :param max_logs: The maximum number of logs to retrieve.
        :type max_logs: int
        :return: The query ID as a string.
        :rtype: str
        """
        try:
            start_time = round(
                self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[0])
            )
            end_time = round(
                self.date_utilities.convert_iso8601_to_unix_timestamp(date_range[1])
            )
            response = client.start_query(
                logGroupName=self.log_group,
                startTime=start_time,
                endTime=end_time,
                queryString=self.query_string,
                limit=max_logs,
            )
            return response["queryId"]
        except client.exceptions.ResourceNotFoundException as e:
            raise DateOutOfBoundsError(f"Resource not found: {e}")


    def _wait_for_query_results(self, client, query_id):
        """
        Waits for the query to complete and retrieves the results.

        :param query_id: The ID of the initiated query.
        :type query_id: str
        :return: A list containing the results of the query.
        :rtype: list
        """
        while True:
            time.sleep(1)
            results = client.get_query_results(queryId=query_id)
            if results["status"] in [
                "Complete",
                "Failed",
                "Cancelled",
                "Timeout",
                "Unknown",
            ]:
                return results.get("results", [])
```
+ 如需 API 詳細資訊，請參閱《適用於 Python (Boto3) 的AWS SDK API 參考》**中的下列主題。
  + [GetQueryResults](https://docs.aws.amazon.com/goto/boto3/logs-2014-03-28/GetQueryResults)
  + [StartQuery](https://docs.aws.amazon.com/goto/boto3/logs-2014-03-28/StartQuery)

### 使用排程事件來調用 Lambda 函式
<a name="cross_LambdaScheduledEvents_python_3_topic"></a>

下列程式碼範例示範如何建立由 Amazon EventBridge 排程事件呼叫的 AWS Lambda 函數。

**適用於 Python 的 SDK (Boto3)**  
 此範例說明如何將 AWS Lambda 函數註冊為排程 Amazon EventBridge 事件的目標。Lambda 處理常式會將合適的訊息和完整的事件資料寫入 Amazon CloudWatch Logs 中以供日後擷取。  
+ 部署 Lambda 函式。
+ 建立一個 EventBridge 排程事件，並將 Lambda 函式做為目標。
+ 授予許可讓 EventBridge 調用 Lambda 函式。
+ 列印 CloudWatch Logs 中的最新資料，以顯示排程調用的結果。
+ 清理示範期間建立的所有資源。
 這個範例在 GitHub 上的檢視效果最佳。如需完整的原始碼和如何設定及執行的指示，請參閱 [GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/python/example_code/lambda#readme) 上的完整範例。  

**此範例中使用的服務**
+ CloudWatch Logs
+ DynamoDB
+ EventBridge
+ Lambda
+ Amazon SNS