- \n
- Basic usage <\/strong>– Just add the handler to any logger<\/li>\n
- Web frameworks<\/strong> – Flask, FastAPI, Django integration<\/li>\n
- Custom configuration<\/strong> – Log groups, streams, formatters<\/li>\n
- Error handling<\/strong> – Exception logging with stack traces<\/li>\n<\/ul>\n
Simple Watchtower Demo Examples<\/h2>\n
1. Basic Usage<\/h3>\n
import watchtower, logging\r\nlogging.basicConfig(level=logging.INFO)\r\nlogger = logging.getLogger(__name__)\r\nlogger.addHandler(watchtower.CloudWatchLogsHandler())\r\nlogger.info(\"Hi\")\r\nlogger.info(dict(foo=\"bar\", details={}))\r\n<\/pre>\n2. Flask App with Watchtower<\/h3>\n
import watchtower, flask, logging\r\nlogging.basicConfig(level=logging.INFO)\r\napp = flask.Flask(\"loggable\")\r\nhandler = watchtower.CloudWatchLogsHandler()\r\napp.logger.addHandler(handler)\r\nlogging.getLogger(\"werkzeug\").addHandler(handler)\r\n\r\n@app.route('\/')\r\ndef hello_world():\r\n return 'Hello World!'\r\n\r\nif __name__ == '__main__':\r\n app.run()\r\n<\/pre>\n3. Custom Log Group and Stream<\/h3>\n
import watchtower, logging\r\nlogger = logging.getLogger('my_app')\r\nhandler = watchtower.CloudWatchLogsHandler(\r\n log_group='my-app-logs',\r\n stream_name='production'\r\n)\r\nlogger.addHandler(handler)\r\nlogger.setLevel(logging.INFO)\r\nlogger.info(\"App started\")\r\n<\/pre>\n4. With Formatter<\/h3>\n
import watchtower, logging\r\nlogger = logging.getLogger('formatted')\r\nhandler = watchtower.CloudWatchLogsHandler()\r\nformatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')\r\nhandler.setFormatter(formatter)\r\nlogger.addHandler(handler)\r\nlogger.setLevel(logging.INFO)\r\nlogger.info(\"Formatted message\")\r\n<\/pre>\nAlso, below are the alternatives of Watchtower in 2025:<\/p>\n
1. Standard Python logging:<\/h2>\n
How It Works<\/h3>\n
By default, Lambda automatically captures logs for all function invocations and sends them to CloudWatch Logs, provided your function’s execution role has the necessary permissions. These logs are, by default, stored in a log group named \/aws\/lambda\/<\/p>\n
import logging<\/strong><\/p>\n
# Configure the logger\r\nlogger = logging.getLogger()\r\nlogger.setLevel(logging.INFO)\r\n\r\ndef lambda_handler(event, context):\r\n logger.info(\"This message will appear in CloudWatch Logs\")\r\n logger.error(\"This error will also appear in CloudWatch Logs\")\r\n \r\n # Even print statements work\r\n print(\"This print statement also goes to CloudWatch\")\r\n \r\n return {\r\n 'statusCode': 200,\r\n 'body': 'Hello World'\r\n }\r\n<\/pre>\n2. AWS Lambda Powertools (Recommended):<\/h2>\n
Logger provides an opinionated logger with output structured as JSON and efficiently handles logs for AWS Lambda, ensuring logs are formatted correctly and recorded in CloudWatch seamlessly.<\/p>\n
from aws_lambda_powertools import Logger\r\nlogger = Logger()\r\n\r\n@logger.inject_lambda_context\r\ndef lambda_handler(event, context):\r\n logger.info(\"Processing event\", extra={\"event\": event})\r\n return {\"statusCode\": 200}\r\n<\/pre>\n3. Direct Boto3 CloudWatch Logs Client<\/h2>\n
You can use Amazon CloudWatch Logs API directly through boto3 to programmatically access and analyze your AWS CloudWatch logs<\/p>\n
import boto3\r\nimport json\r\nfrom datetime import datetime\r\n\r\ndef send_log_to_cloudwatch(message, log_group, log_stream):\r\n client = boto3.client('logs')\r\n timestamp = int(datetime.now().timestamp() * 1000)\r\n client.put_log_events(\r\n logGroupName=log_group,\r\n logStreamName=log_stream,\r\n logEvents=[\r\n {\r\n 'timestamp': timestamp,\r\n 'message': json.dumps(message) if isinstance(message, dict) else str(message)\r\n }\r\n ]\r\n )\r\n<\/pre>\n - Web frameworks<\/strong> – Flask, FastAPI, Django integration<\/li>\n
![\"Also](\"https:\/\/assets.bacancytechnology.com\/qanda\/wp-content\/uploads\/2025\/04\/24061434\/read-txt.png\")