Manhole is in-process service that will accept unix domain socket connections and present the
- Uses unix domain sockets, only root or same effective user can connect.
- Can run the connection in a thread or in a signal handler (see oneshot_on option).
- Can start the thread listening for connections from a signal handler (see activate_on option)
- Compatible with apps that fork, reinstalls the Manhole thread after fork - had to monkeypatch os.fork/os.forkpty for this.
- Compatible with gevent and eventlet with some limitations - you need to either:
- Use oneshot_on, or
- Disable thread monkeypatching (eg: gevent.monkey.patch_all(thread=False), eventlet.monkey_patch(thread=False)
- The thread is compatible with apps that use signalfd (will mask all signals for the Manhole threads).
manhole.install( verbose=True, verbose_destination=2, patch_fork=True, activate_on=None, oneshot_on=None, sigmask=manhole.ALL_SIGNALS, socket_path=None, reinstall_delay=0.5, locals=None, strict=True, )
- verbose - Set it to False to squelch the logging.
- verbose_destination - Destination for verbose messages. Set it to a file descriptor or handle. Default is unbuffered stderr (stderr 2 file descriptor).
- patch_fork - Set it to False if you don’t want your os.fork and os.forkpy monkeypatched
- activate_on - Set to "USR1", "USR2" or some other signal name, or a number if you want the Manhole thread to start when this signal is sent. This is desireable in case you don’t want the thread active all the time.
- thread - Set to True to start the always-on ManholeThread. Default: True. Automatically switched to False if oneshot_on or activate_on are used.
- oneshot_on - Set to "USR1", "USR2" or some other signal name, or a number if you want the Manhole to listen for connection in the signal handler. This is desireable in case you don’t want threads at all.
- sigmask - Will set the signal mask to the given list (using signalfd.sigprocmask). No action is done if signalfd is not importable. NOTE: This is done so that the Manhole thread doesn’t steal any signals; Normally that is fine cause Python will force all the signal handling to be run in the main thread but signalfd doesn’t.
- socket_path - Use a specifc path for the unix domain socket (instead of /tmp/manhole-<pid>). This disables patch_fork as children cannot resuse the same path.
- reinstall_delay - Delay the unix domain socket creation reinstall_delay seconds. This alleviates cleanup failures when using fork+exec patterns.
- locals - Names to add to manhole interactive shell locals.
- daemon_connection - The connection thread is daemonic (dies on app exit). Default: False.
- redirect_stderr - Redirect output from stderr to manhole console. Default: True.
- strict - If True then AlreadyInstalled will be raised when attempting to install manhole twice. Default: True.
Environment variable installation
Manhole can be installed via the PYTHONMANHOLE environment varialbe.
PYTHONMANHOLE='' python yourapp.py
Is equivalent to having this in yourapp.py:
import manhole manhole.install()
Any extra text in the environment variable is passed to manhole.install(). Example:
PYTHONMANHOLE='onshot_on="USR2"' python yourapp.py
What happens when you actually connect to the socket
- Credentials are checked (if it’s same user or root)
- sys.__std*__/sys.std* are be redirected to the UDS
- Stacktraces for each thread are written to the UDS
- REPL is started so you can fiddle with the process
- Using threads and file handle (not raw file descriptor) verbose_destination can cause deadlocks. See bug reports: PyPy and Python 3.4.
SIGTERM and socket cleanup
By default Python doesn’t call the atexit callbacks with the default SIGTERM handling. This makes manhole leave stray socket files around. If this is undesirable you should install a custom SIGTERM handler so atexit is properly invoked.
import signal import sys def handle_sigterm(signo, frame): sys.exit(128 + signo) # this will raise SystemExit and cause atexit to be called signal.signal(signal.SIGTERM, handle_sigterm)
Using Manhole with uWSGI
Because uWSGI overrides signal handling Manhole is a bit more tricky to setup. One way is to use “uWSGI signals” (not the POSIX signals) and have the workers check a file for the pid you want to open the Manhole in.
Stick something this in your WSGI application file:
from __future__ import print_function import sys import os import manhole stack_dump_file = '/tmp/manhole-pid' uwsgi_signal_number = 17 try: import uwsgi if not os.path.exists(stack_dump_file): open(stack_dump_file, 'w') def open_manhole(dummy_signum): with open(stack_dump_file, 'r') as fh: pid = fh.read().strip() if pid == str(os.getpid()): inst = manhole.install(strict=False, thread=False) inst.handle_oneshot(dummy_signum, dummy_signum) uwsgi.register_signal(uwsgi_signal_number, 'workers', open_manhole) uwsgi.add_file_monitor(uwsgi_signal_number, stack_dump_file) print("Listening for stack mahole requests via %r" % (stack_dump_file,), file=sys.stderr) except ImportError: print("Not running under uwsgi; unable to configure manhole trigger", file=sys.stderr) except IOError: print("IOError creating manhole trigger %r" % (stack_dump_file,), file=sys.stderr) # somewhere bellow you'd have something like from django.core.wsgi import get_wsgi_application application = get_wsgi_application() # or def application(environ, start_response): start_response('200 OK', [('Content-Type', 'text/plain'), ('Content-Length', '2')]) yield b'OK'
To open the Manhole just run echo 1234 > /tmp/manhole-pid and then manhole-cli 1234.
|OS:||Linux, OS X|
|Runtime:||Python 2.6, 2.7, 3.2, 3.3, 3.4 or PyPy|
- Twisted’s manhole - it has colors and server-side history.
- wsgi-shell - spawns a thread.
- pyrasite - uses gdb to inject code.
- pydbattach - uses gdb to inject code.
- pystuck - very similar, uses rpyc for communication.
- pyringe - uses gdb to inject code, more reliable, but relies on dbg python builds unfortunatelly.
- pdb-clone - uses gdb to inject code, with a different strategy.
- Added two string aliases for connection_handler option. Now you can convieniently use connection_handler="exec".
- Improved handle_connection_exec. It now has a clean way to exit (exit()) and properly closes the socket.
- Added the connection_handler install option. Default value is manhole.handle_connection_repl, and alternate manhole.handle_connection_exec is provided (very simple: no output redirection, no stacktrace dumping).
- Dropped Python 3.2 from the test grid. It may work but it’s a huge pain to support (pip/pytest don’t support it anymore).
- Added Python 3.5 and 3.6 in the test grid.
- Fixed issues with piping to manhole-cli. Now echo foobar | manhole-cli will wait 1 second for output from manhole (you can customize this with the --timeout option).
- Fixed issues with newer PyPy (caused by gevent/eventlet socket unwrapping).
- Allowed Manhole to be configured without any thread or activation (in case you want to manually activate).
- Added an example and tests for using Manhole with uWSGi.
- Fixed error handling in manhole-cli on Python 3 (exc vars don’t leak anymore).
- Fixed support for running in gevent/eventlet-using apps on Python 3 (now that they support Python 3).
- Allowed reinstalling the manhole (in non-strict mode). Previous install is undone.
- Changed manhole-cli:
- Won’t spam the terminal with errors if socket file doesn’t exist.
- Allowed sending any signal (new --signal argument).
- Fixed some validation issues for the PID argument.
- Added support for installing the manhole via the PYTHONMANHOLE environment variable.
- Added a strict install option. Set it to false to avoid getting the AlreadyInstalled exception.
- Added a manhole-cli script that emulates socat readline unix-connect:/tmp/manhole-1234.
- Fix OS X regression.
- Support for OS X (contributed by Saulius Menkevičius).
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