c1e582586d
Health checks are a way to monitor a service and make sure it stays healthy. If a service is not healthy, it will be automatically restarted after running the unhealthy() function to clean up.
187 lines
5.7 KiB
Groff
187 lines
5.7 KiB
Groff
.\" Copyright (c) 2007-2015 The OpenRC Authors.
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.\" See the Authors file at the top-level directory of this distribution and
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.\" https://github.com/OpenRC/openrc/blob/master/AUTHORS
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.\"
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.\" This file is part of OpenRC. It is subject to the license terms in
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.\" the LICENSE file found in the top-level directory of this
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.\" distribution and at https://github.com/OpenRC/openrc/blob/master/LICENSE
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.\" This file may not be copied, modified, propagated, or distributed
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.\" except according to the terms contained in the LICENSE file.
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.\"
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.Dd April 27, 2016
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.Dt supervise-DAEMON 8 SMM
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.Os OpenRC
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.Sh NAME
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.Nm supervise-daemon
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.Nd starts a daemon and restarts it if it crashes
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.Sh SYNOPSIS
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.Nm
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.Fl a , -healthcheck-timer
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.Ar seconds
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.Fl A , -healthcheck-delay
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.Ar seconds
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.Fl D , -respawn-delay
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.Ar seconds
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.Fl d , -chdir
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.Ar path
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.Fl e , -env
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.Ar var=value
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.Fl g , -group
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.Ar group
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.Fl I , -ionice
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.Ar arg
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.Fl k , -umask
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.Ar value
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.Fl m , -respawn-max
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.Ar count
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.Fl N , -nicelevel
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.Ar level
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.Fl p , -pidfile
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.Ar pidfile
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.Fl P , -respawn-period
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.Ar seconds
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.Fl R , -retry
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.Ar arg
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.Fl r , -chroot
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.Ar chrootpath
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.Fl u , -user
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.Ar user
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.Fl 1 , -stdout
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.Ar logfile
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.Fl 2 , -stderr
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.Ar logfile
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.Fl S , -start
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.Ar daemon
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.Op Fl -
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.Op Ar arguments
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.Nm
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.Fl K , -stop
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.Ar daemon
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.Fl p , -pidfile
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.Ar pidfile
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.Fl r , -chroot
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.Ar chrootpath
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.Sh DESCRIPTION
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.Nm
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provides a consistent method of starting, stopping and restarting
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daemons. If
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.Fl K , -stop
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is not provided, then we assume we are starting the daemon.
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.Nm
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only works with daemons which do not fork. Also, it uses its own pid
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file, so the daemon should not write a pid file, or the pid file passed
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to
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.Nm
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should not be the one the daemon writes.
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.Pp
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Here are the options to specify the daemon and how it should start or stop:
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.Bl -tag -width indent
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.It Fl p , -pidfile Ar pidfile
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When starting, we write a
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.Ar pidfile
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so we know which supervisor to stop. When stopping we only stop the pid(s)
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listed in the
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.Ar pidfile .
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.It Fl u , -user Ar user Ns Op : Ns Ar group
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Start the daemon as the
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.Ar user
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and update $HOME accordingly or stop daemons
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owned by the user. You can optionally append a
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.Ar group
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name here also.
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.It Fl v , -verbose
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Print the action(s) that are taken just before doing them.
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.Pp
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The options are as follows:
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.Bl -tag -width indent
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.Fl a , -healthcheck-timer Ar seconds
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Run the healthcheck() command, possibly followed by the unhealthy()
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command every time this number of seconds passes.
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.Fl A , -healthcheck-delay Ar seconds
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Wait this long before the first health check.
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.It Fl D , -respawn-delay Ar seconds
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wait this number of seconds before restarting a daemon after it crashes.
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The default is 0.
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.It Fl d , -chdir Ar path
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chdir to this directory before starting the daemon.
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.It Fl e , -env Ar VAR=VALUE
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Set the environment variable VAR to VALUE.
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.It Fl g , -group Ar group
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Start the daemon as in the group.
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.It Fl I , -ionice Ar class Ns Op : Ns Ar data
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Modifies the IO scheduling priority of the daemon.
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Class can be 0 for none, 1 for real time, 2 for best effort and 3 for idle.
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Data can be from 0 to 7 inclusive.
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.It Fl k , -umask Ar mode
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Set the umask of the daemon.
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.It Fl m , -respawn-max Ar count
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Sets the maximum number of times a daemon will be respawned during a
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respawn period. If a daemon dies more than this number of times during a
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respawn period,
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.Nm
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will give up trying to respawn it and exit. The default is 10, and 0
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means unlimited.
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.It Fl N , -nicelevel Ar level
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Modifies the scheduling priority of the daemon.
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.It Fl P , -respawn-period Ar seconds
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Sets the length of a respawn period. The default is 10 seconds. See the
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description of --respawn-max for more information.
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.It Fl R , -retry Ar timeout | Ar signal Ns / Ns Ar timeout
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The retry specification can be either a timeout in seconds or multiple
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signal/timeout pairs (like SIGTERM/5).
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If this option is not given, the default is SIGTERM/5.
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.It Fl r , -chroot Ar path
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chroot to this directory before starting the daemon. All other paths, such
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as the path to the daemon, chdir and pidfile, should be relative to the chroot.
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.It Fl u , -user Ar user
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Start the daemon as the specified user.
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.It Fl 1 , -stdout Ar logfile
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Redirect the standard output of the process to logfile.
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Must be an absolute pathname, but relative to the path optionally given with
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.Fl r , -chroot .
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The logfile can also be a named pipe.
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.It Fl 2 , -stderr Ar logfile
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The same thing as
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.Fl 1 , -stdout
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but with the standard error output.
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.El
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.El
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.Sh ENVIRONMENT
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.Va SSD_NICELEVEL
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can also set the scheduling priority of the daemon, but the command line
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option takes precedence.
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.Sh NOTE
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.Nm
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uses
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.Xr getopt 3
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to parse its options, which allows it to accept the `--' option which will
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cause it to stop processing options at that point. Any subsequent arguments
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are passed as arguments to the daemon to start and used when finding a daemon
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to stop or signal.
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.Sh NOTE
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If respawn-delay, respawn-max and respawn-period are not set correctly,
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it is possible to trigger a situation in which the supervisor will
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infinitely try to respawn a daemon. To avoid this, if you change the
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values of --respawn-delay, --respawn-max or --respawn-period, always
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make sure the settings mmake sense. For example, a respawn period of 5
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seconds with a respawn max of 10 and a respawn delay of 1 second leads
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to infinite respawning since there can never be 10 respawns within 5
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seconds.
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.Sh SEE ALSO
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.Xr chdir 2 ,
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.Xr chroot 2 ,
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.Xr getopt 3 ,
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.Xr nice 2 ,
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.Xr rc_find_pids 3
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.Sh BUGS
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.Nm
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cannot stop an interpreted daemon that no longer exists without a pidfile.
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.Sh HISTORY
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.Nm
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first appeared in Debian.
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.Pp
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This is a complete re-implementation with the process finding code in the
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OpenRC library (librc, -lrc) so other programs can make use of it.
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.Sh AUTHORS
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.An William Hubbs <w.d.hubbs@gmail.com>
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