Inpection manhole for python applications. Connection is done via unix domain sockets.
Project description
Manhole is in-process service that will accept unix domain socket connections and present the stacktraces for all threads and an interactive prompt. It can either work as a python daemon thread waiting for connections at all times or a signal handler (stopping your application and waiting for a connection).
Access to the socket is restricted to the application’s effective user id or root.
This is just like Twisted’s manhole. It’s simpler (no dependencies), it only runs on Unix domain sockets (in contrast to Twisted’s manhole which can run on telnet or ssh) and it integrates well with various types of applications.
- Documentation:
Usage
Install it:
pip install manhole
You can put this in your django settings, wsgi app file, some module that’s always imported early etc:
import manhole
manhole.install() # this will start the daemon thread
# and now you start your app, eg: server.serve_forever()
Now in a shell you can do either of these:
netcat -U /tmp/manhole-1234 socat - unix-connect:/tmp/manhole-1234 socat readline unix-connect:/tmp/manhole-1234
Socat with readline is best (history, editing etc).
Sample output:
$ nc -U /tmp/manhole-1234 Python 2.7.3 (default, Apr 10 2013, 06:20:15) [GCC 4.6.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. (InteractiveConsole) >>> dir() ['__builtins__', 'dump_stacktraces', 'os', 'socket', 'sys', 'traceback'] >>> print 'foobar' foobar
Features
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).
Options
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
)
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.
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.
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
Known issues
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.
Example:
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)
Requirements
- OS:
Linux, OS X
- Runtime:
Python 2.6, 2.7, 3.2, 3.3, 3.4 or PyPy
Similar projects
Twisted’s old manhole and the newer implementation (colors, serverside history).
wsgi-shell - spawns a thread.
pyrasite - uses gdb to inject code.
pydbattach - uses gdb to inject code.
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.
Changelog
1.0.0 (2014-10-13)
Added socket_path install option (contributed by Nir Soffer).
Added reinstall_delay install option.
Added locals install option (contributed by Nir Soffer).
Added redirect_stderr install option (contributed by Nir Soffer).
Lots of internals cleanup (contributed by Nir Soffer).
0.6.2 (2014-04-28)
Fix OS X regression.
0.6.1 (2014-04-28)
Support for OS X (contributed by Saulius Menkevičius).
Project details
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