add document on logging

docs/index.rst

@@ -20,6 +20,7 @@ Guides
    sanic/class_based_views
    sanic/custom_protocol
    sanic/ssl
+   sanic/logging
    sanic/testing
    sanic/deploying
    sanic/extensions

docs/sanic/logging.md

@@ -0,0 +1,128 @@
+# Logging
+
+
+Sanic allows you to do different types of logging (access log, error log) on the requests based on the [python3 logging API](https://docs.python.org/3/howto/logging.html). You should have some basic knowledge on python3 logging if you want do create a new configuration.
+
+### Quck Start
+
+A simple example using default setting would be like this:
+
+```python
+from sanic import Sanic
+from sanic.config import LOGGING
+
+# The default logging handlers are ['accessStream', 'errorStream']
+# but we change it to use other handlers here for demo purpose
+LOGGING['loggers']['network']['handlers'] = [
+    'accessTimedRotatingFile', 'errorTimedRotationgFile']
+
+app = Sanic('test')
+
+@app.route('/')
+async def test(request):
+    return response.text('Hello World!')
+
+if __name__ == "__main__":
+  app.run(log_config=LOGGING)
+```
+
+After the program starts, it will log down all the information/requests in access.log and error.log in your working directory.
+
+And to close logging, simply assign log_config=None:
+
+```python
+if __name__ == "__main__":
+  app.run(log_config=None)
+```
+
+This would skip calling logging functions when handling requests.
+And you could even do further in production to gain extra speed:
+
+```python
+if __name__ == "__main__":
+  # disable internal messages
+  app.run(debug=False, log_config=None)
+```
+
+### Configuration
+
+By default, log_config parameter is set to use sanic.config.LOGGING dictionary for configuration. The default configuration provides several predefined `handlers`:
+
+- internal (using [logging.StreamHandler](https://docs.python.org/3/library/logging.handlers.html#logging.StreamHandler))<br>
+  For internal information console outputs.
+
+
+- accessStream (using [logging.StreamHandler](https://docs.python.org/3/library/logging.handlers.html#logging.StreamHandler))<br>
+  For requests information logging in console
+
+
+- errorStream (using [logging.StreamHandler](https://docs.python.org/3/library/logging.handlers.html#logging.StreamHandler))<br>
+  For error message and traceback logging in console.
+
+
+- accessSysLog (using [logging.handlers.SysLogHandler](https://docs.python.org/3/library/logging.handlers.html#logging.handlers.SysLogHandler))<br>
+  For requests information logging to syslog.
+  Currently supports Windows (via localhost:514), Darwin (/var/run/syslog),
+  Linux (/dev/log) and FreeBSD (/dev/log).<br>
+  You would not be able to access this property if the directory doesn't exist.
+  (Notice that in Docker you have to enable everything by yourself)
+
+
+- errorSysLog (using [logging.handlers.SysLogHandler](https://docs.python.org/3/library/logging.handlers.html#logging.handlers.SysLogHandler))<br>
+  For error message and traceback logging to syslog.
+  Currently supports Windows (via localhost:514), Darwin (/var/run/syslog),
+  Linux (/dev/log) and FreeBSD (/dev/log).<br>
+  You would not be able to access this property if the directory doesn't exist.
+  (Notice that in Docker you have to enable everything by yourself)
+
+
+- accessTimedRotatingFile (using [logging.handlers.TimedRotatingFileHandler](https://docs.python.org/3/library/logging.handlers.html#logging.handlers.TimedRotatingFileHandler))<br>
+  For requests information logging to file with daily rotation support.
+
+
+- errorTimedRotatingFile (using [logging.handlers.TimedRotatingFileHandler](https://docs.python.org/3/library/logging.handlers.html#logging.handlers.TimedRotatingFileHandler))<br>
+  For error message and traceback logging to file with daily rotation support.
+
+And `filters`:
+
+- accessFilter (using sanic.defaultFilter.DefaultFilter)<br>
+  The filter that allows only levels in `DEBUG`, `INFO`, and `NONE(0)`
+
+
+- errorFilter (using sanic.defaultFilter.DefaultFilter)<br>
+  The filter taht allows only levels in `WARNING`, `ERROR`, and `CRITICAL`
+
+There are two `loggers` used in sanic, and **must be defined if you want to create your own logging configuration**:
+
+- sanic:<br>
+  Used to log internal messages.
+
+
+- network:<br>
+  Used to log requests from network, and any information from those requests.
+
+#### Log format:
+
+In addition to default parameters provided by python (asctime, levelname, message),
+Sanic provides additional parameters for network logger with accessFilter:
+
+- host (str)<br>
+  request.ip
+
+
+- request (str)<br>
+  request.method + " " + request.url
+
+
+- status (int)<br>
+  response.status
+
+
+- byte (int)<br>
+  len(response.body)
+
+
+The default access log format is 
+```python
+%(asctime)s - (%(name)s)[%(levelname)s][%(host)s]: %(request)s %(message)s %(status)d %(byte)d
+```