Log all requests from the python-requests module

When trying to get the Python logging system (import logging) to emit low level debug log messages, it suprised me to discover that given:

requests --> urllib3 --> http.client.HTTPConnection

that only urllib3 actually uses the Python logging system:

  • requests no
  • http.client.HTTPConnection no
  • urllib3 yes

Sure, you can extract debug messages from HTTPConnection by setting:

HTTPConnection.debuglevel = 1

but these outputs are merely emitted via the print statement. To prove this, simply grep the Python 3.7 client.py source code and view the print statements yourself (thanks @Yohann):

curl https://raw.githubusercontent.com/python/cpython/3.7/Lib/http/client.py |grep -A1 debuglevel`

Presumably redirecting stdout in some way might work to shoe-horn stdout into the logging system and potentially capture to e.g. a log file.

Choose the 'urllib3' logger not 'requests.packages.urllib3'

To capture urllib3 debug information through the Python 3 logging system, contrary to much advice on the internet, and as @MikeSmith points out, you won’t have much luck intercepting:

log = logging.getLogger('requests.packages.urllib3')

instead you need to:

log = logging.getLogger('urllib3')

Debugging urllib3 to a log file

Here is some code which logs urllib3 workings to a log file using the Python logging system:

import requests
import logging
from http.client import HTTPConnection  # py3

# log = logging.getLogger('requests.packages.urllib3')  # useless
log = logging.getLogger('urllib3')  # works

log.setLevel(logging.DEBUG)  # needed
fh = logging.FileHandler("requests.log")
log.addHandler(fh)

requests.get('http://httpbin.org/')

the result:

Starting new HTTP connection (1): httpbin.org:80
http://httpbin.org:80 "GET / HTTP/1.1" 200 3168

Enabling the HTTPConnection.debuglevel print() statements

If you set HTTPConnection.debuglevel = 1 

from http.client import HTTPConnection  # py3
HTTPConnection.debuglevel = 1
requests.get('http://httpbin.org/')

you'll get the print statement output of additional juicy low level info:

send: b'GET / HTTP/1.1\r\nHost: httpbin.org\r\nUser-Agent: python- 
requests/2.22.0\r\nAccept-Encoding: gzip, deflate\r\nAccept: */*\r\nConnection: keep-alive\r\n\r\n'
reply: 'HTTP/1.1 200 OK\r\n'
header: Access-Control-Allow-Credentials header: Access-Control-Allow-Origin 
header: Content-Encoding header: Content-Type header: Date header: ...

Remember this output uses print and not the Python logging system, and thus cannot be captured using a traditional logging stream or file handler (though it may be possible to capture output to a file by redirecting stdout).

Combine the two above - maximise all possible logging to console

To maximise all possible logging, you must settle for console/stdout output with this:

import requests
import logging
from http.client import HTTPConnection  # py3

log = logging.getLogger('urllib3')
log.setLevel(logging.DEBUG)

# logging from urllib3 to console
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)
log.addHandler(ch)

# print statements from `http.client.HTTPConnection` to console/stdout
HTTPConnection.debuglevel = 1

requests.get('http://httpbin.org/')

giving the full range of output:

Starting new HTTP connection (1): httpbin.org:80
send: b'GET / HTTP/1.1\r\nHost: httpbin.org\r\nUser-Agent: python-requests/2.22.0\r\nAccept-Encoding: gzip, deflate\r\nAccept: */*\r\nConnection: keep-alive\r\n\r\n'
reply: 'HTTP/1.1 200 OK\r\n'
http://httpbin.org:80 "GET / HTTP/1.1" 200 3168
header: Access-Control-Allow-Credentials header: Access-Control-Allow-Origin 
header: Content-Encoding header: ...

For those using python 3+

import requests
import logging
import http.client

http.client.HTTPConnection.debuglevel = 1

logging.basicConfig()
logging.getLogger().setLevel(logging.DEBUG)
requests_log = logging.getLogger("requests.packages.urllib3")
requests_log.setLevel(logging.DEBUG)
requests_log.propagate = True

The underlying urllib3 library logs all new connections and URLs with the logging module, but not POST bodies. For GET requests this should be enough:

import logging

logging.basicConfig(level=logging.DEBUG)

which gives you the most verbose logging option; see the logging HOWTO for more details on how to configure logging levels and destinations.

Short demo:

>>> import requests
>>> import logging
>>> logging.basicConfig(level=logging.DEBUG)
>>> r = requests.get('http://httpbin.org/get?foo=bar&baz=python')
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): httpbin.org:80
DEBUG:urllib3.connectionpool:http://httpbin.org:80 "GET /get?foo=bar&baz=python HTTP/1.1" 200 366

Depending on the exact version of urllib3, the following messages are logged:

  • INFO: Redirects
  • WARN: Connection pool full (if this happens often increase the connection pool size)
  • WARN: Failed to parse headers (response headers with invalid format)
  • WARN: Retrying the connection
  • WARN: Certificate did not match expected hostname
  • WARN: Received response with both Content-Length and Transfer-Encoding, when processing a chunked response
  • DEBUG: New connections (HTTP or HTTPS)
  • DEBUG: Dropped connections
  • DEBUG: Connection details: method, path, HTTP version, status code and response length
  • DEBUG: Retry count increments

This doesn't include headers or bodies. urllib3 uses the http.client.HTTPConnection class to do the grunt-work, but that class doesn't support logging, it can normally only be configured to print to stdout. However, you can rig it to send all debug information to logging instead by introducing an alternative print name into that module:

import logging
import http.client

httpclient_logger = logging.getLogger("http.client")

def httpclient_logging_patch(level=logging.DEBUG):
    """Enable HTTPConnection debug logging to the logging framework"""

    def httpclient_log(*args):
        httpclient_logger.log(level, " ".join(args))

    # mask the print() built-in in the http.client module to use
    # logging instead
    http.client.print = httpclient_log
    # enable debugging
    http.client.HTTPConnection.debuglevel = 1

Calling httpclient_logging_patch() causes http.client connections to output all debug information to a standard logger, and so are picked up by logging.basicConfig():

>>> httpclient_logging_patch()
>>> r = requests.get('http://httpbin.org/get?foo=bar&baz=python')
DEBUG:urllib3.connectionpool:Starting new HTTP connection (1): httpbin.org:80
DEBUG:http.client:send: b'GET /get?foo=bar&baz=python HTTP/1.1\r\nHost: httpbin.org\r\nUser-Agent: python-requests/2.22.0\r\nAccept-Encoding: gzip, deflate\r\nAccept: */*\r\nConnection: keep-alive\r\n\r\n'
DEBUG:http.client:reply: 'HTTP/1.1 200 OK\r\n'
DEBUG:http.client:header: Date: Tue, 04 Feb 2020 13:36:53 GMT
DEBUG:http.client:header: Content-Type: application/json
DEBUG:http.client:header: Content-Length: 366
DEBUG:http.client:header: Connection: keep-alive
DEBUG:http.client:header: Server: gunicorn/19.9.0
DEBUG:http.client:header: Access-Control-Allow-Origin: *
DEBUG:http.client:header: Access-Control-Allow-Credentials: true
DEBUG:urllib3.connectionpool:http://httpbin.org:80 "GET /get?foo=bar&baz=python HTTP/1.1" 200 366

You need to enable debugging at httplib level (requests → urllib3 → httplib).

Here's some functions to both toggle (..._on() and ..._off()) or temporarily have it on:

import logging
import contextlib
try:
    from http.client import HTTPConnection # py3
except ImportError:
    from httplib import HTTPConnection # py2

def debug_requests_on():
    '''Switches on logging of the requests module.'''
    HTTPConnection.debuglevel = 1

    logging.basicConfig()
    logging.getLogger().setLevel(logging.DEBUG)
    requests_log = logging.getLogger("requests.packages.urllib3")
    requests_log.setLevel(logging.DEBUG)
    requests_log.propagate = True

def debug_requests_off():
    '''Switches off logging of the requests module, might be some side-effects'''
    HTTPConnection.debuglevel = 0

    root_logger = logging.getLogger()
    root_logger.setLevel(logging.WARNING)
    root_logger.handlers = []
    requests_log = logging.getLogger("requests.packages.urllib3")
    requests_log.setLevel(logging.WARNING)
    requests_log.propagate = False

@contextlib.contextmanager
def debug_requests():
    '''Use with 'with'!'''
    debug_requests_on()
    yield
    debug_requests_off()

Demo use:

>>> requests.get('http://httpbin.org/')
<Response [200]>

>>> debug_requests_on()
>>> requests.get('http://httpbin.org/')
INFO:requests.packages.urllib3.connectionpool:Starting new HTTP connection (1): httpbin.org
DEBUG:requests.packages.urllib3.connectionpool:"GET / HTTP/1.1" 200 12150
send: 'GET / HTTP/1.1\r\nHost: httpbin.org\r\nConnection: keep-alive\r\nAccept-
Encoding: gzip, deflate\r\nAccept: */*\r\nUser-Agent: python-requests/2.11.1\r\n\r\n'
reply: 'HTTP/1.1 200 OK\r\n'
header: Server: nginx
...
<Response [200]>

>>> debug_requests_off()
>>> requests.get('http://httpbin.org/')
<Response [200]>

>>> with debug_requests():
...     requests.get('http://httpbin.org/')
INFO:requests.packages.urllib3.connectionpool:Starting new HTTP connection (1): httpbin.org
...
<Response [200]>

You will see the REQUEST, including HEADERS and DATA, and RESPONSE with HEADERS but without DATA. The only thing missing will be the response.body which is not logged.

Source

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