Logging

We use structlog to format the logs generated by the application. We redirect the logs to STDOUT as JSON. You need to use an external system to collect an aggregate the logs.

Lego contains a middleware that binds request information to each log message. There is no need to add things like request path and authenticated user to the log message, this is done automatically.

Import and use the logger

from structlog import get_logger

log = get_logger()

log.warn('important_message', message_recipient=user.username)

Celery and structlog

If you also want to add the request context to log messages in celery tasks you have to use a special task base and bind the task. Also remember to call the setup_logger function.

@celery_app.task(bind=True, base=AbakusTask)
def task_name(self, normal_argument, logger_context=None):
   self.setup_logger(logger_context)
   other work...
class lego.utils.tasks.AbakusTask

Bases: celery.app.task.Task

This base task supplies the logger_context to the underlying worker.

> @celery_app.task(bind=True, base=AbakusTask) > def task_name(self, logger_context=None): > self.setup_logger(logger_context) > other work…

apply_async(args=None, kwargs=None, *arguments, **keyword_arguments)

Apply tasks asynchronously by sending a message.

Arguments:

args (Tuple): The positional arguments to pass on to the task.

kwargs (Dict): The keyword arguments to pass on to the task.

countdown (float): Number of seconds into the future that the
task should execute. Defaults to immediate execution.
eta (~datetime.datetime): Absolute time and date of when the task
should be executed. May not be specified if countdown is also supplied.
expires (float, ~datetime.datetime): Datetime or
seconds in the future for the task should expire. The task won’t be executed after the expiration time.
shadow (str): Override task name used in logs/monitoring.
Default is retrieved from shadow_name().
connection (kombu.Connection): Re-use existing broker connection
instead of acquiring one from the connection pool.
retry (bool): If enabled sending of the task message will be
retried in the event of connection loss or failure. Default is taken from the :setting:`task_publish_retry` setting. Note that you need to handle the producer/connection manually for this to work.
retry_policy (Mapping): Override the retry policy used.
See the :setting:`task_publish_retry_policy` setting.
queue (str, kombu.Queue): The queue to route the task to.
This must be a key present in :setting:`task_queues`, or :setting:`task_create_missing_queues` must be enabled. See guide-routing for more information.
exchange (str, kombu.Exchange): Named custom exchange to send the
task to. Usually not used in combination with the queue argument.
routing_key (str): Custom routing key used to route the task to a
worker server. If in combination with a queue argument only used to specify custom routing keys to topic exchanges.
priority (int): The task priority, a number between 0 and 9.
Defaults to the priority attribute.
serializer (str): Serialization method to use.
Can be pickle, json, yaml, msgpack or any custom serialization method that’s been registered with kombu.serialization.registry. Defaults to the serializer attribute.
compression (str): Optional compression method
to use. Can be one of zlib, bzip2, or any custom compression methods registered with kombu.compression.register(). Defaults to the :setting:`task_compression` setting.
link (Signature): A single, or a list of tasks signatures
to apply if the task returns successfully.
link_error (Signature): A single, or a list of task signatures
to apply if an error occurs while executing the task.
producer (kombu.Producer): custom producer to use when publishing
the task.
add_to_parent (bool): If set to True (default) and the task
is applied while executing another task, then the result will be appended to the parent tasks request.children attribute. Trailing can also be disabled by default using the trail attribute

publisher (kombu.Producer): Deprecated alias to producer.

headers (Dict): Message headers to be included in the message.

Returns:
celery.result.AsyncResult: Promise of future evaluation.
Raises:
TypeError: If not enough arguments are passed, or too many
arguments are passed. Note that signature checks may be disabled by specifying @task(typing=False).
kombu.exceptions.OperationalError: If a connection to the
transport cannot be made, or if the connection is lost.
Note:
Also supports all keyword arguments supported by kombu.Producer.publish().