Hi folks, today, I’ve release the 0.2.0 of my structlog project whose ambition is no less than changing the way we log in Python. :) And since it sports dedicated support for Twisted <http://www.structlog.org/en/latest/twisted.html> (but is not limited to it, it wraps *any* logger), I’d like to introduce you to it. Basically, its premise is that events happen in a context and you want to log out both effortlessly. Nowadays logs are usually consumed by parsers anyway, so regular, easily parsable logs are a good thing™. This is a nice example of a Twisted application showing off a bit what structlog is capable of: import sys import uuid import structlog import twisted from twisted.internet import protocol, reactor logger = structlog.getLogger() class Counter(object): i = 0 def inc(self): self.i += 1 def __repr__(self): return str(self.i) class Echo(protocol.Protocol): def connectionMade(self): self._counter = Counter() self._log = logger.new( connection_id=str(uuid.uuid4()), peer=self.transport.getPeer().host, count=self._counter, ) def dataReceived(self, data): self._counter.inc() log = self._log.bind(data=data) self.transport.write(data) log.msg('echoed data!') if __name__ == "__main__": structlog.configure( processors=[structlog.twisted.EventAdapter()], logger_factory=structlog.twisted.LoggerFactory(), ) twisted.python.log.startLogging(sys.stderr) reactor.listenTCP(1234, protocol.Factory.forProtocol(Echo)) reactor.run() It will give you an output like: 2013-09-17 17:40:23+0200 [-] Log opened. 2013-09-17 17:40:23+0200 [-] Factory starting on 1234 2013-09-17 17:40:23+0200 [-] Starting factory <twisted.internet.protocol.Factory instance at 0x108301488> 2013-09-17 17:40:28+0200 [Echo,0,127.0.0.1] peer='127.0.0.1' count=1 connection_id='4e2ee31c-b3ff-478e-ae06-7b1a492fce45' data='foo\n' event='echoed data!' 2013-09-17 17:40:33+0200 [Echo,0,127.0.0.1] peer='127.0.0.1' count=2 connection_id='4e2ee31c-b3ff-478e-ae06-7b1a492fce45' data='bar\n' event='echoed data!' 2013-09-17 17:40:44+0200 [Echo,1,127.0.0.1] peer='127.0.0.1' count=1 connection_id='3118f673-482b-471f-a206-e8f97f9a9c2c' data='qux\n' event='echoed data!' 2013-09-17 17:40:53+0200 [Echo,0,127.0.0.1] peer='127.0.0.1' count=3 connection_id='4e2ee31c-b3ff-478e-ae06-7b1a492fce45' data='twisted prevails\n' event='echoed data!' (you can find this and more examples at <http://www.structlog.org/en/latest/examples.html>) In short: - It allows you to build context by binding values to loggers. This context is just a dictionary. Once you log an event out (again, arbitrary number of key/value pairs), it gets merged with the context, processed by configurable processor chain and passed to your original logger. - Your loggers are immutable (by default infidels can use thread local storage) and you’ll get a new one on each binding. Immutable local data is awesome. - You can define processors that can mangle, filter, and format your log entries. - Configure once, then just call getLogger (which is a Twisted-friendly alias for get_logger) in regular code. - Of course there is a JSON renderer built right in – just tell log stash about it and be merry. *Please* have a look at <http://www.structlog.org/en/0.2.0-0/getting-started.html>, I don’t want to reproduce it here. :) Credit where credit is due: I picked up the idea of bound loggers from David Reid’s work on otter <https://github.com/rackerlabs/otter/tree/master/otter/log> which in turn was based on ideas by JP (I’ve been told). You can find everything you need to know at http://www.structlog.org/ – I’d be happy about any constructive feedback and even more so about contributions! Cheers, Hynek