Logging

Scrapy provides a logging facility which can be used through the scrapy.log module. The current underlying implementation uses Twisted logging but this may change in the future.

The logging service must be explicitly started through the scrapy.log.start() function to catch the top level Scrapy’s log messages. On top of that, each crawler has its own independent log observer (automatically attached when it’s created) that intercepts its spider’s log messages.

Log levels

Scrapy provides 5 logging levels:

  1. CRITICAL - for critical errors
  2. ERROR - for regular errors
  3. WARNING - for warning messages
  4. INFO - for informational messages
  5. DEBUG - for debugging messages

How to set the log level

You can set the log level using the –loglevel/-L command line option, or using the LOG_LEVEL setting.

How to log messages

Here’s a quick example of how to log a message using the WARNING level:

from scrapy import log
log.msg("This is a warning", level=log.WARNING)

Logging from Spiders

The recommended way to log from spiders is by using the Spider log() method, which already populates the spider argument of the scrapy.log.msg() function. The other arguments are passed directly to the msg() function.

scrapy.log module

scrapy.log.start(logfile=None, loglevel=None, logstdout=None)

Start the top level Scrapy logger. This must be called before actually logging any top level messages (those logged using this module’s msg() function instead of the Spider.log method). Otherwise, messages logged before this call will get lost.

Parameters:
  • logfile (str) – the file path to use for logging output. If omitted, the LOG_FILE setting will be used. If both are None, the log will be sent to standard error.
  • loglevel – the minimum logging level to log. Available values are: CRITICAL, ERROR, WARNING, INFO and DEBUG.
  • logstdout (boolean) – if True, all standard output (and error) of your application will be logged instead. For example if you “print ‘hello’” it will appear in the Scrapy log. If omitted, the LOG_STDOUT setting will be used.
scrapy.log.msg(message, level=INFO, spider=None)

Log a message

Parameters:
  • message (str) – the message to log
  • level – the log level for this message. See Log levels.
  • spider (Spider object) – the spider to use for logging this message. This parameter should always be used when logging things related to a particular spider.
scrapy.log.CRITICAL

Log level for critical errors

scrapy.log.ERROR

Log level for errors

scrapy.log.WARNING

Log level for warnings

scrapy.log.INFO

Log level for informational messages (recommended level for production deployments)

scrapy.log.DEBUG

Log level for debugging messages (recommended level for development)

Logging settings

These settings can be used to configure the logging: