Django uses Python’s builtin logging module to perform system logging.\nThe usage of this module is discussed in detail in Python’s own documentation.\nHowever, if you’ve never used Python’s logging framework (or even if you have),\nhere’s a quick primer.
A Python logging configuration consists of four parts:
\nA logger is the entry point into the logging system. Each logger is\na named bucket to which messages can be written for processing.
\nA logger is configured to have a log level. This log level describes\nthe severity of the messages that the logger will handle. Python\ndefines the following log levels:
\nDEBUG: Low level system information for debugging purposes
INFO: General system information
WARNING: Information describing a minor problem that has\noccurred.
ERROR: Information describing a major problem that has\noccurred.
CRITICAL: Information describing a critical problem that has\noccurred.
Each message that is written to the logger is a Log Record. Each log\nrecord also has a log level indicating the severity of that specific\nmessage. A log record can also contain useful metadata that describes\nthe event that is being logged. This can include details such as a\nstack trace or an error code.
\nWhen a message is given to the logger, the log level of the message is\ncompared to the log level of the logger. If the log level of the\nmessage meets or exceeds the log level of the logger itself, the\nmessage will undergo further processing. If it doesn’t, the message\nwill be ignored.
\nOnce a logger has determined that a message needs to be processed,\nit is passed to a Handler.
\nThe handler is the engine that determines what happens to each message\nin a logger. It describes a particular logging behavior, such as\nwriting a message to the screen, to a file, or to a network socket.
\nLike loggers, handlers also have a log level. If the log level of a\nlog record doesn’t meet or exceed the level of the handler, the\nhandler will ignore the message.
\nA logger can have multiple handlers, and each handler can have a\ndifferent log level. In this way, it is possible to provide different\nforms of notification depending on the importance of a message. For\nexample, you could install one handler that forwards ERROR and\nCRITICAL messages to a paging service, while a second handler\nlogs all messages (including ERROR and CRITICAL messages) to a\nfile for later analysis.
A filter is used to provide additional control over which log records\nare passed from logger to handler.
\nBy default, any log message that meets log level requirements will be\nhandled. However, by installing a filter, you can place additional\ncriteria on the logging process. For example, you could install a\nfilter that only allows ERROR messages from a particular source to\nbe emitted.
Filters can also be used to modify the logging record prior to being\nemitted. For example, you could write a filter that downgrades\nERROR log records to WARNING records if a particular set of\ncriteria are met.
Filters can be installed on loggers or on handlers; multiple filters\ncan be used in a chain to perform multiple filtering actions.
\nUltimately, a log record needs to be rendered as text. Formatters\ndescribe the exact format of that text. A formatter usually consists\nof a Python formatting string containing\nLogRecord attributes; however,\nyou can also write custom formatters to implement specific formatting behavior.
\nOnce you have configured your loggers, handlers, filters and\nformatters, you need to place logging calls into your code. Using the\nlogging framework is very simple. Here’s an example:
\n# import the logging library\nimport logging\n\n# Get an instance of a logger\nlogger = logging.getLogger(__name__)\n\ndef my_view(request, arg1, arg):\n ...\n if bad_mojo:\n # Log an error message\n logger.error('Something went wrong!')\nAnd that’s it! Every time the bad_mojo condition is activated, an\nerror log record will be written.
The call to logging.getLogger() obtains (creating, if\nnecessary) an instance of a logger. The logger instance is identified\nby a name. This name is used to identify the logger for configuration\npurposes.
By convention, the logger name is usually __name__, the name of\nthe python module that contains the logger. This allows you to filter\nand handle logging calls on a per-module basis. However, if you have\nsome other way of organizing your logging messages, you can provide\nany dot-separated name to identify your logger:
# Get an instance of a specific named logger\nlogger = logging.getLogger('project.interesting.stuff')\nThe dotted paths of logger names define a hierarchy. The\nproject.interesting logger is considered to be a parent of the\nproject.interesting.stuff logger; the project logger\nis a parent of the project.interesting logger.
Why is the hierarchy important? Well, because loggers can be set to\npropagate their logging calls to their parents. In this way, you can\ndefine a single set of handlers at the root of a logger tree, and\ncapture all logging calls in the subtree of loggers. A logging handler\ndefined in the project namespace will catch all logging messages\nissued on the project.interesting and\nproject.interesting.stuff loggers.
This propagation can be controlled on a per-logger basis. If\nyou don’t want a particular logger to propagate to its parents, you\ncan turn off this behavior.
\nThe logger instance contains an entry method for each of the default\nlog levels:
\nlogger.debug()
logger.info()
logger.warning()
logger.error()
logger.critical()
There are two other logging calls available:
\nlogger.log(): Manually emits a logging message with a\nspecific log level.
logger.exception(): Creates an ERROR level logging\nmessage wrapping the current exception stack frame.
Of course, it isn’t enough to just put logging calls into your code.\nYou also need to configure the loggers, handlers, filters and\nformatters to ensure that logging output is output in a useful way.
\nPython’s logging library provides several techniques to configure\nlogging, ranging from a programmatic interface to configuration files.\nBy default, Django uses the dictConfig format.
\nIn order to configure logging, you use LOGGING to define a\ndictionary of logging settings. These settings describes the loggers,\nhandlers, filters and formatters that you want in your logging setup,\nand the log levels and other properties that you want those components\nto have.
By default, the LOGGING setting is merged with Django’s\ndefault logging configuration using the\nfollowing scheme.
If the disable_existing_loggers key in the LOGGING dictConfig is\nset to True (which is the default) then all loggers from the default\nconfiguration will be disabled. Disabled loggers are not the same as removed;\nthe logger will still exist, but will silently discard anything logged to it,\nnot even propagating entries to a parent logger. Thus you should be very\ncareful using 'disable_existing_loggers': True; it’s probably not what you\nwant. Instead, you can set disable_existing_loggers to False and\nredefine some or all of the default loggers; or you can set\nLOGGING_CONFIG to None and handle logging config yourself.
Logging is configured as part of the general Django setup() function.\nTherefore, you can be certain that loggers are always ready for use in your\nproject code.
The full documentation for dictConfig format\nis the best source of information about logging configuration dictionaries.\nHowever, to give you a taste of what is possible, here are several examples.
\nFirst, here’s a simple configuration which writes all logging from the\ndjango logger to a local file:
\nLOGGING = {\n 'version': 1,\n 'disable_existing_loggers': False,\n 'handlers': {\n 'file': {\n 'level': 'DEBUG',\n 'class': 'logging.FileHandler',\n 'filename': '/path/to/django/debug.log',\n },\n },\n 'loggers': {\n 'django': {\n 'handlers': ['file'],\n 'level': 'DEBUG',\n 'propagate': True,\n },\n },\n}\nIf you use this example, be sure to change the 'filename' path to a\nlocation that’s writable by the user that’s running the Django application.
Second, here’s an example of how to make the logging system print Django’s\nlogging to the console. It may be useful during local development.
\nBy default, this config only sends messages of level INFO or higher to the\nconsole (same as Django’s default logging config, except that the default only\ndisplays log records when DEBUG=True). Django does not log many such\nmessages. With this config, however, you can also set the environment variable\nDJANGO_LOG_LEVEL=DEBUG to see all of Django’s debug logging which is very\nverbose as it includes all database queries:
import os\n\nLOGGING = {\n 'version': 1,\n 'disable_existing_loggers': False,\n 'handlers': {\n 'console': {\n 'class': 'logging.StreamHandler',\n },\n },\n 'loggers': {\n 'django': {\n 'handlers': ['console'],\n 'level': os.getenv('DJANGO_LOG_LEVEL', 'INFO'),\n },\n },\n}\nFinally, here’s an example of a fairly complex logging setup:
\nLOGGING = {\n 'version': 1,\n 'disable_existing_loggers': False,\n 'formatters': {\n 'verbose': {\n 'format': '%(levelname)s %(asctime)s %(module)s %(process)d %(thread)d %(message)s'\n },\n 'simple': {\n 'format': '%(levelname)s %(message)s'\n },\n },\n 'filters': {\n 'special': {\n '()': 'project.logging.SpecialFilter',\n 'foo': 'bar',\n },\n 'require_debug_true': {\n '()': 'django.utils.log.RequireDebugTrue',\n },\n },\n 'handlers': {\n 'console': {\n 'level': 'INFO',\n 'filters': ['require_debug_true'],\n 'class': 'logging.StreamHandler',\n 'formatter': 'simple'\n },\n 'mail_admins': {\n 'level': 'ERROR',\n 'class': 'django.utils.log.AdminEmailHandler',\n 'filters': ['special']\n }\n },\n 'loggers': {\n 'django': {\n 'handlers': ['console'],\n 'propagate': True,\n },\n 'django.request': {\n 'handlers': ['mail_admins'],\n 'level': 'ERROR',\n 'propagate': False,\n },\n 'myproject.custom': {\n 'handlers': ['console', 'mail_admins'],\n 'level': 'INFO',\n 'filters': ['special']\n }\n }\n}\nThis logging configuration does the following things:
\nIdentifies the configuration as being in «dictConfig version 1»\nformat. At present, this is the only dictConfig format version.
Defines two formatters:
\nsimple, that just outputs the log level name (e.g.,\nDEBUG) and the log message.
The format string is a normal Python formatting string\ndescribing the details that are to be output on each logging\nline. The full list of detail that can be output can be\nfound in Formatter Objects.
verbose, that outputs the log level name, the log\nmessage, plus the time, process, thread and module that\ngenerate the log message.
Defines two filters:
\nproject.logging.SpecialFilter, using the alias special. If this\nfilter required additional arguments, they can be provided as additional\nkeys in the filter configuration dictionary. In this case, the argument\nfoo will be given a value of bar when instantiating\nSpecialFilter.
django.utils.log.RequireDebugTrue, which passes on records when\nDEBUG is True.
Defines two handlers:
\nconsole, a StreamHandler, which will print any INFO\n(or higher) message to stderr. This handler uses the simple output\nformat.
mail_admins, an AdminEmailHandler, which will email any\nERROR (or higher) message to the site admins. This handler uses\nthe special filter.
Configures three loggers:
\ndjango, which passes all messages to the console handler.
django.request, which passes all ERROR messages to\nthe mail_admins handler. In addition, this logger is\nmarked to not propagate messages. This means that log\nmessages written to django.request will not be handled\nby the django logger.
myproject.custom, which passes all messages at INFO\nor higher that also pass the special filter to two\nhandlers – the console, and mail_admins. This\nmeans that all INFO level messages (or higher) will be\nprinted to the console; ERROR and CRITICAL\nmessages will also be output via email.
If you don’t want to use Python’s dictConfig format to configure your\nlogger, you can specify your own configuration scheme.
\nThe LOGGING_CONFIG setting defines the callable that will\nbe used to configure Django’s loggers. By default, it points at\nPython’s logging.config.dictConfig() function. However, if you want to\nuse a different configuration process, you can use any other callable\nthat takes a single argument. The contents of LOGGING will\nbe provided as the value of that argument when logging is configured.
If you don’t want to configure logging at all (or you want to manually\nconfigure logging using your own approach), you can set\nLOGGING_CONFIG to None. This will disable the\nconfiguration process for Django’s default logging. Here’s an example that disables Django’s\nlogging configuration and then manually configures logging:
settings.pyLOGGING_CONFIG = None\n\nimport logging.config\nlogging.config.dictConfig(...)\nSetting LOGGING_CONFIG to None only means that the automatic\nconfiguration process is disabled, not logging itself. If you disable the\nconfiguration process, Django will still make logging calls, falling back to\nwhatever default logging behavior is defined.
Django provides a number of utilities to handle the unique\nrequirements of logging in Web server environment.
\nDjango provides several built-in loggers.
\ndjangoLink to this heading#The catch-all logger for messages in the django hierarchy. No messages are\nposted using this name but instead using one of the loggers below.
django.requestLink to this heading#Log messages related to the handling of requests. 5XX responses are\nraised as ERROR messages; 4XX responses are raised as WARNING\nmessages.
Messages to this logger have the following extra context:
\nstatus_code: The HTTP response code associated with the\nrequest.
request: The request object that generated the logging\nmessage.
django.serverLink to this heading#Log messages related to the handling of requests received by the server invoked\nby the runserver command. HTTP 5XX responses are logged as ERROR\nmessages, 4XX responses are logged as WARNING messages, and everything else\nis logged as INFO.
Messages to this logger have the following extra context:
\nstatus_code: The HTTP response code associated with the request.
request: The request object that generated the logging message.
django.templateLink to this heading#Log messages related to the rendering of templates.
\nMissing context variables are logged as DEBUG messages.
Uncaught exceptions raised during the rendering of an\n{% include %} are logged as WARNING messages when\ndebug mode is off (helpful since {% include %} silences the exception and\nreturns an empty string in that case).
django.db.backendsLink to this heading#Messages relating to the interaction of code with the database. For example,\nevery application-level SQL statement executed by a request is logged at the\nDEBUG level to this logger.
Messages to this logger have the following extra context:
\nduration: The time taken to execute the SQL statement.
sql: The SQL statement that was executed.
params: The parameters that were used in the SQL call.
For performance reasons, SQL logging is only enabled when\nsettings.DEBUG is set to True, regardless of the logging\nlevel or handlers that are installed.
This logging does not include framework-level initialization (e.g.\nSET TIMEZONE) or transaction management queries (e.g. BEGIN,\nCOMMIT, and ROLLBACK). Turn on query logging in your database if you\nwish to view all database queries.
django.security.*Link to this heading#The security loggers will receive messages on any occurrence of\nSuspiciousOperation and other security-related\nerrors. There is a sub-logger for each subtype of security error, including all\nSuspiciousOperations. The level of the log event depends on where the\nexception is handled. Most occurrences are logged as a warning, while\nany SuspiciousOperation that reaches the WSGI handler will be logged as an\nerror. For example, when an HTTP Host header is included in a request from\na client that does not match ALLOWED_HOSTS, Django will return a 400\nresponse, and an error message will be logged to the\ndjango.security.DisallowedHost logger.
These log events will reach the django logger by default, which mails error\nevents to admins when DEBUG=False. Requests resulting in a 400 response due\nto a SuspiciousOperation will not be logged to the django.request\nlogger, but only to the django.security logger.
To silence a particular type of SuspiciousOperation, you can override that\nspecific logger following this example:
'handlers': {\n 'null': {\n 'class': 'logging.NullHandler',\n },\n},\n'loggers': {\n 'django.security.DisallowedHost': {\n 'handlers': ['null'],\n 'propagate': False,\n },\n},\nOther django.security loggers not based on SuspiciousOperation are:
django.security.csrf: For CSRF failures.
django.db.backends.schemaLink to this heading#Logs the SQL queries that are executed during schema changes to the database by\nthe migrations framework. Note that it won’t log the\nqueries executed by RunPython.\nMessages to this logger have params and sql in their extra context (but\nunlike django.db.backends, not duration). The values have the same meaning\nas explained in django.db.backends.
Django provides one log handler in addition to those provided by the\nPython logging module.
\nThis handler sends an email to the site admins for each log\nmessage it receives.
\nIf the log record contains a request attribute, the full details\nof the request will be included in the email. The email subject will\ninclude the phrase „internal IP” if the client’s IP address is in the\nINTERNAL_IPS setting; if not, it will include „EXTERNAL IP”.
If the log record contains stack trace information, that stack\ntrace will be included in the email.
\nThe include_html argument of AdminEmailHandler is used to\ncontrol whether the traceback email includes an HTML attachment\ncontaining the full content of the debug Web page that would have been\nproduced if DEBUG were True. To set this value in your\nconfiguration, include it in the handler definition for\ndjango.utils.log.AdminEmailHandler, like this:
'handlers': {\n 'mail_admins': {\n 'level': 'ERROR',\n 'class': 'django.utils.log.AdminEmailHandler',\n 'include_html': True,\n }\n},\nNote that this HTML version of the email contains a full traceback,\nwith names and values of local variables at each level of the stack, plus\nthe values of your Django settings. This information is potentially very\nsensitive, and you may not want to send it over email. Consider using\nsomething such as Sentry to get the best of both worlds – the\nrich information of full tracebacks plus the security of not sending the\ninformation over email. You may also explicitly designate certain\nsensitive information to be filtered out of error reports – learn more on\nFiltering error reports.
\nBy setting the email_backend argument of AdminEmailHandler, the\nemail backend that is being used by the\nhandler can be overridden, like this:
'handlers': {\n 'mail_admins': {\n 'level': 'ERROR',\n 'class': 'django.utils.log.AdminEmailHandler',\n 'email_backend': 'django.core.mail.backends.filebased.EmailBackend',\n }\n},\nBy default, an instance of the email backend specified in\nEMAIL_BACKEND will be used.
Sends emails to admin users. To customize this behavior, you can\nsubclass the AdminEmailHandler class and\noverride this method.
Django provides two log filters in addition to those provided by the Python\nlogging module.
\nThis filter accepts a callback function (which should accept a single\nargument, the record to be logged), and calls it for each record that\npasses through the filter. Handling of that record will not proceed if the\ncallback returns False.
\nFor instance, to filter out UnreadablePostError\n(raised when a user cancels an upload) from the admin emails, you would\ncreate a filter function:
from django.http import UnreadablePostError\n\ndef skip_unreadable_post(record):\n if record.exc_info:\n exc_type, exc_value = record.exc_info[:2]\n if isinstance(exc_value, UnreadablePostError):\n return False\n return True\nand then add it to your logging config:
\n'filters': {\n 'skip_unreadable_posts': {\n '()': 'django.utils.log.CallbackFilter',\n 'callback': skip_unreadable_post,\n }\n},\n'handlers': {\n 'mail_admins': {\n 'level': 'ERROR',\n 'filters': ['skip_unreadable_posts'],\n 'class': 'django.utils.log.AdminEmailHandler'\n }\n},\nThis filter will only pass on records when settings.DEBUG is False.
\nThis filter is used as follows in the default LOGGING\nconfiguration to ensure that the AdminEmailHandler only sends\nerror emails to admins when DEBUG is False:
'filters': {\n 'require_debug_false': {\n '()': 'django.utils.log.RequireDebugFalse',\n }\n},\n'handlers': {\n 'mail_admins': {\n 'level': 'ERROR',\n 'filters': ['require_debug_false'],\n 'class': 'django.utils.log.AdminEmailHandler'\n }\n},\nThis filter is similar to RequireDebugFalse, except that records are\npassed only when DEBUG is True.
By default, Django configures the following logging:
\nWhen DEBUG is True:
The django logger sends messages in the django hierarchy (except\ndjango.server) at the INFO level or higher to the console.
When DEBUG is False:
The django logger sends messages in the django hierarchy (except\ndjango.server) with ERROR or CRITICAL level to\nAdminEmailHandler.
Independent of the value of DEBUG:
The django.server logger sends messages at the INFO level\nor higher to the console.
See also Configuring logging to learn how you can\ncomplement or replace this default logging configuration.
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