Format Airflow Logs in JSON

Question

I have a requirement to log the Apache Airflow logs to stdout in JSON format. Airflow does not seem to project this capability out of the box. I have found a couple python modules that are capable of this task, but I cannot get the implementation to work.

Currently, I am applying a class in airflow/utils/logging.py to modify the logger, shown below:

from pythonjsonlogger import jsonlogger

class StackdriverJsonFormatter(jsonlogger.JsonFormatter, object):
def __init__(self, fmt="%(levelname) %(asctime) %(nanotime) %(severity) %(message)", style='%', *args, **kwargs):
    jsonlogger.JsonFormatter.__init__(self, fmt=fmt, *args, **kwargs)

def process_log_record(self, log_record):
    if log_record.get('level'):
        log_record['severity'] = log_record['level']
        del log_record['level']
    else: 
        log_record['severity'] = log_record['levelname']
        del log_record['levelname']
    if log_record.get('asctime'):
        log_record['timestamp'] = log_record['asctime']
        del log_record['asctime']
    now = datetime.datetime.now().strftime('%Y-%m-%dT%H:%M:%S.%fZ')
    log_record['nanotime'] = now
    return super(StackdriverJsonFormatter, self).process_log_record(log_record)

I am implementing this code in /airflow/settings.py as shown below:

from airflow.utils import logging as logconf

def configure_logging(log_format=LOG_FORMAT):
     handler = logconf.logging.StreamHandler(sys.stdout)
     formatter = logconf.StackdriverJsonFormatter()
     handler.setFormatter(formatter)
     logging = logconf.logging.getLogger()
     logging.addHandler(handler)
''' code below was original airflow source code
     logging.root.handlers = []
     logging.basicConfig(
         format=log_format, stream=sys.stdout, level=LOGGING_LEVEL)
'''

I have tried a couple different variations of this and can't get the python-json-logger to transform the logs to JSON. Perhaps I'm not getting to the root logger? Another option I have considered is manually formatting the logs to a JSON string. No luck with that yet either. Any alternative ideas, tips, or support are appreciated.

Cheers!

Answer 1

I don't know if you ever solved this problem, but after some frustrating tinkering, I ended up getting this to play nice with airflow. For reference, I followed a lot of this article to get it working: https://www.astronomer.io/guides/logging/. The main issue was that the airflow logging only accepts a string template for the logging format, which json-logging can't plug into. So you have to create your own logging classes and connect it to a custom logging config class.

1. Copy the log template here into your $AIRFLOW_HOME/config folder, and change DEFAULT_CONFIG_LOGGING to CONFIG_LOGGING. When you're successful, bring up airflow and you'll get a log message on airflow startup that says Successfully imported user-defined logging config from logging_config.LOGGING_CONFIG. If this is the first .py file in the config folder don't forget to add a blank __init__.py file to get python to pick it up

2. Write your custom JsonFormatter to inject into your handler. I did mine off of this one.

3. Write the custom log handler classes. Since I was looking for JSON logging, mine look like this:

from airflow.utils.log.file_processor_handler import FileProcessorHandler
from airflow.utils.log.file_task_handler import FileTaskHandler
from airflow.utils.log.logging_mixin import RedirectStdHandler
from pythonjsonlogger import jsonlogger

class JsonStreamHandler(RedirectStdHandler):
    def __init__(self, stream):
        super(JsonStreamHandler, self).__init__(stream)
        json_formatter = CustomJsonFormatter('(timestamp) (level) (name) (message)')
        self.setFormatter(json_formatter)


class JsonFileTaskHandler(FileTaskHandler):
    def __init__(self, base_log_folder, filename_template):
        super(JsonFileTaskHandler, self).__init__(base_log_folder, filename_template)
        json_formatter = CustomJsonFormatter('(timestamp) (level) (name) (message)')
        self.setFormatter(json_formatter)


class JsonFileProcessorHandler(FileProcessorHandler):
    def __init__(self, base_log_folder, filename_template):
        super(JsonFileProcessorHandler, self).__init__(base_log_folder, filename_template)
        json_formatter = CustomJsonFormatter('(timestamp) (level) (name) (message)')
        self.setFormatter(json_formatter)


class JsonRotatingFileHandler(RotatingFileHandler):
    def __init__(self, filename, mode, maxBytes, backupCount):
        super(JsonRotatingFileHandler, self).__init__(filename, mode, maxBytes, backupCount)
        json_formatter = CustomJsonFormatter('(timestamp) (level) (name) (message)')
        self.setFormatter(json_formatter)

4. Hook them up to the logging configs in your custom logging_config.py file.

'handlers': {
    'console': {
        'class': 'logging_handler.JsonStreamHandler',
        'stream': 'sys.stdout'
    },
    'task': {
        'class': 'logging_handler.JsonFileTaskHandler',
        'base_log_folder': os.path.expanduser(BASE_LOG_FOLDER),
        'filename_template': FILENAME_TEMPLATE,
    },
    'processor': {
        'class': 'logging_handler.JsonFileProcessorHandler',
        'base_log_folder': os.path.expanduser(PROCESSOR_LOG_FOLDER),
        'filename_template': PROCESSOR_FILENAME_TEMPLATE,
    }
}
...

and

DEFAULT_DAG_PARSING_LOGGING_CONFIG = {
    'handlers': {
        'processor_manager': {
            'class': 'logging_handler.JsonRotatingFileHandler',
            'formatter': 'airflow',
            'filename': DAG_PROCESSOR_MANAGER_LOG_LOCATION,
            'mode': 'a',
            'maxBytes': 104857600,  # 100MB
            'backupCount': 5
        }
    }
...

And json logs should be output, both in the DAG logs and the output as well.

Hope this helps!