daemon-spec
This is a brief description of a Python 3 wrapper for modules that allows them to be run as a proper daemon. Initially at least this capability will be confined to Linux systms and possibly only to Debian and Ubuntu distributions.
Tenatively this behavior will be built on top of python-daemon and
its DaemonContext.
For the purposes of this document we will assume that the daemon
package is called zDaemon and that there is a companiion locking
facility zLocks which is expected to be a separate module.
Daemonization Candidates
We assume that any program to be daemonized using this module will
- accept options through
sys.argv - expect to store and retrieve files through paths relative to its current directory
Expected Implementation Style
Call the program to be daemonized Candidate. Typically this will
be packaged as a separate module, perhaps candidate.py. This should
have a conventional Python entry point main(), so that the last two
lines of candidate.py are
if _name__ == '__main__':
main()
Then the program can be run as a standalone script using
PATH_TO_SCRIPT/candidate/main() ARGV
where ARGV represents the usual sequence of arguments passed through
sys.argv.
zDaemon is invoked similarl
zDaemon ARGV
with the understanding that zDaemon will consume at least some of the
leading arguments, stripping them off before passing the remaining
arguments to the candidate.
This allows the candidate program to be thoroughly tested independently
of zDaemon.
