aiofluent 1.2.9
A Python logging handler for Fluentd event collector
License: Apache License, Version 2.0

A Python structured logger for Fluentd
======================================

WARNING: This is a fork of the https://github.com/fluent/fluent-logger-python
project to work with asyncio.


Many web/mobile applications generate huge amount of event logs (c,f.
login, logout, purchase, follow, etc). To analyze these event logs could
be really valuable for improving the service. However, the challenge is
collecting these logs easily and reliably.

`Fluentd <https://github.com/fluent/fluentd>`__ solves that problem by
having: easy installation, small footprint, plugins, reliable buffering,
log forwarding, etc.

**aiofluent** is a Python library, to record the events from
Python application.

Requirements
------------

-  Python 3.5 or greater
- ``msgpack-python``

Installation
------------

This library is distributed as 'aiofluent' python package. Please
execute the following command to install it.

.. code:: sh

    $ pip install aiofluent

Configuration
-------------

Fluentd daemon must be launched with a tcp source configuration:

::

    <source>
      type forward
      port 24224
    </source>

To quickly test your setup, add a matcher that logs to the stdout:

::

    <match app.**>
      type stdout
    </match>

Usage
-----

FluentSender Interface
~~~~~~~~~~~~~~~~~~~~~~

`sender.FluentSender` is a structured event logger for Fluentd.

By default, the logger assumes fluentd daemon is launched locally. You
can also specify remote logger by passing the options.

.. code:: python

    from aiofluent import sender

    # for local fluent
    logger = sender.FluentSender('app')

    # for remote fluent
    logger = sender.FluentSender('app', host='host', port=24224)

For sending event, call `emit` method with your event. Following example will send the event to
fluentd, with tag 'app.follow' and the attributes 'from' and 'to'.

.. code:: python

    # Use current time
    logger.emit('follow', {'from': 'userA', 'to': 'userB'})

    # Specify optional time
    cur_time = int(time.time())
    logger.emit_with_time('follow', cur_time, {'from': 'userA', 'to':'userB'})

You can detect an error via return value of `emit`. If an error happens in `emit`, `emit` returns `False` and get an error object using `last_error` method.

.. code:: python

    if not logger.emit('follow', {'from': 'userA', 'to': 'userB'}):
        print(logger.last_error)
        logger.clear_last_error() # clear stored error after handled errors

If you want to shutdown the client, call `close()` method.

.. code:: python

    logger.close()

Event-Based Interface
~~~~~~~~~~~~~~~~~~~~~

This API is a wrapper for `sender.FluentSender`.

First, you need to call ``sender.setup()`` to create global `sender.FluentSender` logger
instance. This call needs to be called only once, at the beginning of
the application for example.

Initialization code of Event-Based API is below:

.. code:: python

    from aiofluent import sender

    # for local fluent
    sender.setup('app')

    # for remote fluent
    sender.setup('app', host='host', port=24224)

Then, please create the events like this. This will send the event to
fluentd, with tag 'app.follow' and the attributes 'from' and 'to'.

.. code:: python

    from aiofluent import event

    # send event to fluentd, with 'app.follow' tag
    event.Event('follow', {
      'from': 'userA',
      'to':   'userB'
    })

`event.Event` has one limitation which can't return success/failure result.

Other methods for Event-Based Interface.

.. code:: python

    sender.get_global_sender # get instance of global sender
    sender.close # Call FluentSender#close

Handler for buffer overflow
~~~~~~~~~~~~~~~~~~~~~~~~~~~

You can inject your own custom proc to handle buffer overflow in the event of connection failure. This will mitigate the loss of data instead of simply throwing data away.

.. code:: python

    import msgpack
    from io import BytesIO

    def handler(pendings):
        unpacker = msgpack.Unpacker(BytesIO(pendings))
        for unpacked in unpacker:
            print(unpacked)

    logger = sender.FluentSender('app', host='host', port=24224, buffer_overflow_handler=handler)

You should handle any exception in handler. aiofluent ignores exceptions from ``buffer_overflow_handler``.

This handler is also called when pending events exist during `close()`.

Python logging.Handler interface
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This client-library also has ``FluentHandler`` class for Python logging
module.

.. code:: python

    import logging
    from aiofluent import handler

    custom_format = {
      'host': '%(hostname)s',
      'where': '%(module)s.%(funcName)s',
      'type': '%(levelname)s',
      'stack_trace': '%(exc_text)s'
    }

    logging.basicConfig(level=logging.INFO)
    l = logging.getLogger('fluent.test')
    h = handler.FluentHandler('app.follow', host='host', port=24224)
    formatter = handler.FluentRecordFormatter(custom_format)
    h.setFormatter(formatter)
    l.addHandler(h)
    l.info({
      'from': 'userA',
      'to': 'userB'
    })
    l.info('{"from": "userC", "to": "userD"}')
    l.info("This log entry will be logged with the additional key: 'message'.")

You can also customize formatter via logging.config.dictConfig

.. code:: python

    import logging.config
    import yaml

    with open('logging.yaml') as fd:
        conf = yaml.load(fd)

    logging.config.dictConfig(conf['logging'])

A sample configuration ``logging.yaml`` would be:

.. code:: python

    logging:
        version: 1

        formatters:
          brief:
            format: '%(message)s'
          default:
            format: '%(asctime)s %(levelname)-8s %(name)-15s %(message)s'
            datefmt: '%Y-%m-%d %H:%M:%S'
          fluent_fmt:
            '()': fluent.handler.FluentRecordFormatter
            format:
              level: '%(levelname)s'
              hostname: '%(hostname)s'
              where: '%(module)s.%(funcName)s'

        handlers:
            console:
                class : logging.StreamHandler
                level: DEBUG
                formatter: default
                stream: ext://sys.stdout
            fluent:
                class: fluent.handler.FluentHandler
                host: localhost
                port: 24224
                tag: test.logging
                formatter: fluent_fmt
                level: DEBUG
            none:
                class: logging.NullHandler

        loggers:
            amqp:
                handlers: [none]
                propagate: False
            conf:
                handlers: [none]
                propagate: False
            '': # root logger
                handlers: [console, fluent]
                level: DEBUG
                propagate: False

License
-------

Apache License, Version 2.0


1.2.9 (2020-10-22)
------------------

- Only log errors every 30 seconds


1.2.8 (2020-05-15)
------------------

- Handle TypeError formatting log data


1.2.7 (2020-03-09)
------------------

- Fix repo location


1.2.6 (2020-01-06)
------------------

- Improve error logging
  [vangheem]

1.2.5 (2019-12-19)
------------------

- Handle event loop closed error
  [vangheem]


1.2.4 (2019-12-19)
------------------

- Increase max queue size


1.2.3 (2019-04-01)
------------------

- Fix release


1.2.2 (2019-04-01)
------------------

- nanosecond_precision by default
  [davidonna]

1.2.1 (2018-10-31)
------------------

- Add support for nanosecond precision timestamps
  [davidonna]

1.2.0 (2018-06-14)
------------------

- Maintain one AsyncIO queue for all logs
  [vangheem]

1.1.4 (2018-05-29)
------------------

- Handle RuntimeError on canceling tasks/cleanup
  [vangheem]


1.1.3 (2018-02-15)
------------------

- Lock calling the close method of sender
  [vangheem]

- Increase default timeout
  [vangheem]


1.1.2 (2018-02-07)
------------------

- lock the whole method
  [vangheem]


1.1.1 (2018-02-07)
------------------

- Use lock on getting connection object
  [vangheem]


1.1.0 (2018-01-25)
------------------

- Move to using asyncio connection infrastructure instead of sockets
  [vangheem]


1.0.8 (2018-01-04)
------------------

- Always close out buffer data
  [vangheem]


1.0.7 (2018-01-04)
------------------

- Handle errors processing log queue
  [vangheem]


1.0.6 (2017-11-14)
------------------

- Prevent log queue from getting too large
  [vangheem]


1.0.5 (2017-10-17)
------------------

- Fix release to include CHANGELOG.rst file
  [vangheem]


1.0.4 (2017-10-10)
------------------

- Fix pushing initial record


1.0.3 (2017-10-10)
------------------

- Handle Runtime error when logging done before event loop started
  [vangheem]


1.0.2 (2017-10-09)
------------------

- Fix to make normal logging call async
  [vangheem]


1.0.1 (2017-07-03)
------------------

- initial release