hupper¶
hupper
is monitor for your Python process. When files change, the process
will be restarted. It can be extended to watch arbitrary files. Reloads can
also be triggered manually from code. File monitoring can be done using
basic polling or using inotify-style filesystem events if watchdog is
installed.
Installation¶
Stable release¶
To install hupper, run this command in your terminal:
$ pip install hupper
If you don’t have pip installed, this Python installation guide can guide you through the process.
From sources¶
The sources for hupper can be downloaded from the Github repo.
$ git clone https://github.com/Pylons/hupper.git
Once you have a copy of the source, you can install it with:
$ pip install -e .
Watchdog support¶
If watchdog is installed, it will be used to more efficiently watch for changes to files.
$ pip install watchdog
This is an optional dependency and if it’s not installed, then hupper
will
fallback to less efficient polling of the filesystem.
Command-line Usage¶
Hupper can load any Python code similar to python -m <module>
by using the
hupper -m <module>
program.
$ hupper -m myapp
Starting monitor for PID 23982.
API Usage¶
The reloading mechanism is implemented by forking worker processes from a
parent monitor. Start by defining an entry point for your process. This must
be an importable path in string format. For example,
myapp.scripts.serve.main
:
# myapp/scripts/serve.py
import sys
import hupper
import waitress
def wsgi_app(environ, start_response):
start_response('200 OK', [('Content-Type', 'text/plain'])
yield [b'hello']
def main(args=sys.argv[1:]):
if '--reload' in args:
# start_reloader will only return in a monitored subprocess
reloader = hupper.start_reloader('myapp.scripts.serve.main')
# monitor an extra file
reloader.watch_files(['foo.ini'])
waitress.serve(wsgi_app)
Many applications will tend to re-use the same startup code for both the
monitor and the worker. As a convenience to support this use case, the
hupper.start_reloader()
function can be invoked both from the parent
process as well as the worker. When called initially from the parent process,
it will fork a new worker, then start the monitor and never return. When
called from the worker process it will return a proxy object that can be used
to communicate back to the monitor.
Checking if the reloader is active¶
hupper.is_active()
will return True
if the reloader is active and
the current process may be reloaded.
Controlling the monitor¶
The worker processes may communicate back to the monitor and notify it of
new files to watch. This can be done by acquiring a reference to the
hupper.interfaces.IReloaderProxy
instance living in the worker
process. The hupper.start_reloader()
function will return the instance
or hupper.get_reloader()
can be used as well.