Python Daemonizer Class

This is a Python class that will daemonize your Python script so it can continue running in the background. It works on Unix, Linux and OS X, creates a PID file and has standard commands (start, stop, restart) plus a foreground mode.

Based on this original version from jejik.com.

Quick Start

Usage

Define a class which inherits from Daemon and has a run() method (which is what will be called once the daemonization is completed).

from daemon import Daemon


class pantalaimon(Daemon):
    def run(self):
        do_mything()

Depending on what your code is doing, you may also want to subclass the cleanup() method to close sockets, etc (called after stop() and before termination).

Create a new object of your class, specifying where you want your PID file to exist:

pineMarten = pantalaimon("/path/to/pid.pid")
pineMarten.start()

Actions

• start - start the daemon (create PID and daemonize)
• stop - stop the daemon (stop the child process and remove the PID)
• restart - run stop then start
• status - show daemon status

Foreground

This is useful for debugging because you can start the code without making it a daemon. The running script then depends on the open shell like any normal Python script.

To do this, just call the run() method directly instead of start():

pineMarten.run()

Continuous execution

The run() method will be executed just once so if you want the daemon to be doing stuff continuously you may wish to use the schedule module to execute code snippets repeatedly (examples). For another example that does not use a scheduler, see the pyserv httpdaemon script.

Install with pip

This updated version is not published on PyPI, thus use one of the following commands to install the latest python-daemonizer in a Python virtual environment on any platform.

From source:

$ python3 -m venv env
$ source env/bin/activate
$ pip install git+https://github.com/sarnold/python-daemonizer.git

The alternative to python venv is the Tox test driver. If you have it installed already, clone this repository and try the following commands from the python-daemonizer source directory.

To install in dev mode and run the tests:

$ tox -e py

To run pylint:

$ tox -e lint

Note

After installing in dev mode, use the environment created by Tox just like any other Python virtual environment. The dev install mode of Pip allows you to edit the script and run it again while inside the virtual environment. By default Tox environments are created under .tox/ and named after the env argument (eg, py).

To install the latest release, eg with your own tox.ini file in another project, use something like this:

$ pip install -U -f https://github.com/sarnold/python-daemonizer/releases/ daemonizer

Pre-commit

This repo is now pre-commit enabled for python/rst source and file-type linting. The checks run automatically on commit and will fail the commit (if not clean) and perform simple file corrections. For example, if the mypy check fails on commit, you must first fix any fatal errors for the commit to succeed. That said, pre-commit does nothing if you don't install it first (both the program itself and the hooks in your local repository copy).

You will need to install pre-commit before contributing any changes; installing it using your system's package manager is recommended, otherwise install with pip into your usual virtual environment using something like:

$ sudo emerge pre-commit  --or--
$ pip install pre-commit

then install it into the repo you just cloned:

$ git clone https://github.com/sarnold/python-daemonizer
$ cd python-daemonizer/
$ pre-commit install

It's usually a good idea to update the hooks to the latest version:

$ pre-commit autoupdate

Most (but not all) of the pre-commit checks will make corrections for you, however, some will only report errors, so these you will need to correct manually.

Automatic-fix checks include ffffff, isort, autoflake, and miscellaneous file fixers. If any of these fail, you can review the changes with git diff and just add them to your commit and continue.

If any of the mypy, bandit, or rst source checks fail, you will get a report, and you must fix any errors before you can continue adding/committing.

To see a "replay" of any rst check errors, run:

$ pre-commit run rst-backticks -a
$ pre-commit run rst-directive-colons -a
$ pre-commit run rst-inline-touching-normal -a

To run all pre-commit checks manually, try:

$ pre-commit run -a