[Buildbot] #3608: Running with --nodaemon and PID files

[Buildbot trac]

#3608: Running with --nodaemon and PID files
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Reporter:  gracinet  |      Owner:
    Type:  defect    |     Status:  new
Priority:  minor     |  Milestone:  0.9.+
 Version:  0.8.12    |   Keywords:
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 Both the master and the worker still use PID files while running with
 --nodaemon. I've had issues with workers running with --nodaemon not
 starting because of an old, stale PID file, corresponding to an actual
 process belonging to another user.

 This can be thought to be inconsistent, and harms the writing ofreally
 simple non forking configuration files to manage the process through an
 external service manager (systemd, supervisord etc.).

 It seems that the cousin ``twistd`` executable has a --pidfile argument,
 that can be used to mean "no pid file". This is explained notably in
 https://twistedmatrix.com/documents/current/core/howto/systemd.html.

 We could expose that, or we could decide that --nodaemon implies no pid
 file.

 I believe this is true in Eight and Nine, and that a fix could be easily
 backported
 (marking this as minor, because it's easy to circumvent by putting
 appropriate rms in unit files or other confs)

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Ticket URL: <http://trac.buildbot.net/ticket/3608>
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