Logging

If you need to inspect the internal behaviour of httpx, you can use Python's standard logging to output information about the underlying network behaviour.

For example, the following configuration...

import logging
import httpx

logging.basicConfig(
    format="%(levelname)s [%(asctime)s] %(name)s - %(message)s",
    datefmt="%Y-%m-%d %H:%M:%S",
    level=logging.DEBUG
)

httpx.get("https://www.example.com")

Will send debug level output to the console, or wherever stdout is directed too...

DEBUG [2023-03-16 14:36:20] httpx - load_ssl_context verify=True cert=None trust_env=True http2=False
DEBUG [2023-03-16 14:36:20] httpx - load_verify_locations cafile='/Users/tomchristie/GitHub/encode/httpx/venv/lib/python3.10/site-packages/certifi/cacert.pem'
DEBUG [2023-03-16 14:36:20] httpcore - connection.connect_tcp.started host='www.example.com' port=443 local_address=None timeout=5.0
DEBUG [2023-03-16 14:36:20] httpcore - connection.connect_tcp.complete return_value=<httpcore.backends.sync.SyncStream object at 0x1068fd270>
DEBUG [2023-03-16 14:36:20] httpcore - connection.start_tls.started ssl_context=<ssl.SSLContext object at 0x10689aa40> server_hostname='www.example.com' timeout=5.0
DEBUG [2023-03-16 14:36:20] httpcore - connection.start_tls.complete return_value=<httpcore.backends.sync.SyncStream object at 0x1068fd240>
DEBUG [2023-03-16 14:36:20] httpcore - http11.send_request_headers.started request=<Request [b'GET']>
DEBUG [2023-03-16 14:36:20] httpcore - http11.send_request_headers.complete
DEBUG [2023-03-16 14:36:20] httpcore - http11.send_request_body.started request=<Request [b'GET']>
DEBUG [2023-03-16 14:36:20] httpcore - http11.send_request_body.complete
DEBUG [2023-03-16 14:36:20] httpcore - http11.receive_response_headers.started request=<Request [b'GET']>
DEBUG [2023-03-16 14:36:21] httpcore - http11.receive_response_headers.complete return_value=(b'HTTP/1.1', 200, b'OK', [(b'Content-Encoding', b'gzip'), (b'Accept-Ranges', b'bytes'), (b'Age', b'507675'), (b'Cache-Control', b'max-age=604800'), (b'Content-Type', b'text/html; charset=UTF-8'), (b'Date', b'Thu, 16 Mar 2023 14:36:21 GMT'), (b'Etag', b'"3147526947+ident"'), (b'Expires', b'Thu, 23 Mar 2023 14:36:21 GMT'), (b'Last-Modified', b'Thu, 17 Oct 2019 07:18:26 GMT'), (b'Server', b'ECS (nyb/1D2E)'), (b'Vary', b'Accept-Encoding'), (b'X-Cache', b'HIT'), (b'Content-Length', b'648')])
INFO [2023-03-16 14:36:21] httpx - HTTP Request: GET https://www.example.com "HTTP/1.1 200 OK"
DEBUG [2023-03-16 14:36:21] httpcore - http11.receive_response_body.started request=<Request [b'GET']>
DEBUG [2023-03-16 14:36:21] httpcore - http11.receive_response_body.complete
DEBUG [2023-03-16 14:36:21] httpcore - http11.response_closed.started
DEBUG [2023-03-16 14:36:21] httpcore - http11.response_closed.complete
DEBUG [2023-03-16 14:36:21] httpcore - connection.close.started
DEBUG [2023-03-16 14:36:21] httpcore - connection.close.complete

Logging output includes information from both the high-level httpx logger, and the network-level httpcore logger, which can be configured separately.

For handling more complex logging configurations you might want to use the dictionary configuration style...

import logging.config
import httpx

LOGGING_CONFIG = {
    "version": 1,
    "handlers": {
        "default": {
            "class": "logging.StreamHandler",
            "formatter": "http",
            "stream": "ext://sys.stderr"
        }
    },
    "formatters": {
        "http": {
            "format": "%(levelname)s [%(asctime)s] %(name)s - %(message)s",
            "datefmt": "%Y-%m-%d %H:%M:%S",
        }
    },
    'loggers': {
        'httpx': {
            'handlers': ['default'],
            'level': 'DEBUG',
        },
        'httpcore': {
            'handlers': ['default'],
            'level': 'DEBUG',
        },
    }
}

logging.config.dictConfig(LOGGING_CONFIG)
httpx.get('https://www.example.com')

The exact formatting of the debug logging may be subject to change across different versions of httpx and httpcore. If you need to rely on a particular format it is recommended that you pin installation of these packages to fixed versions.