python-daemon and PID files

Ben Finney ben+python at benfinney.id.au
Mon Mar 6 05:50:06 EST 2017


Ethan Furman <ethan at stoneleaf.us> writes:

> On 03/04/2017 09:09 PM, Ian Pilcher wrote:
>
> > Is it possible to get python-daemon to create "systemd style" PID
> > file?

Short answer: No, that's the job of whatever ‘pidfile’ object you
provide.


Medium answer: Yes, by implementing that behaviour in the object you
choose to present as the ‘pidfile’ option. The ‘python-lockfile’ library
is suggested as one implementation, but there are of course others.


Longer answer: Because ‘python-daemon’ is deliberately agnostic about
what the ‘pidfile’ object does, you can give it any behaviour you like.

The only thing the ‘DaemonContext.pidfile’ option is expected to do is
be a context manager; what happens when that context manager is entered
or exited is up to you.

> I know my library, pandaemonium [1], will allow you to write the pid
> file complete with the daemon's PID, and I would be very surprised if
> Ben's python-daemon did not also allow that.

It certainly allows it: put whatever behaviour your application needs in
the context manager's methods.

More about writing a context manager can be found at the documentation
<URL:https://docs.python.org/3/reference/datamodel.html#with-statement-context-managers>.

-- 
 \       “If we listen only to those who are like us, we will squander |
  `\   the great opportunity before us: To live together peacefully in |
_o__)            a world of unresolved differences.” —David Weinberger |
Ben Finney



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