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Date:      Tue, 12 Jan 2021 00:43:57 +1100
From:      Scott <freebsd-lists-5@thismonkey.com>
To:        Polytropon <freebsd@edvax.de>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Need help specifying args in rc.conf for a service
Message-ID:  <X/xWHReL/tarF8Ic@thismonkey.com>
In-Reply-To: <20210111143139.278aec37.freebsd@edvax.de>
References:  <X/w9IwVAFXyDr/ir@thismonkey.com> <20210111132107.82de40d0.freebsd@edvax.de> <X/xKy6Y6Cl4+zkhd@thismonkey.com> <20210111143139.278aec37.freebsd@edvax.de>

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On Mon, Jan 11, 2021 at 02:31:39PM +0100, Polytropon wrote:
> On Mon, 11 Jan 2021 23:55:39 +1100, Scott wrote:
> > On Mon, Jan 11, 2021 at 01:21:07PM +0100, Polytropon wrote:
> > > On Mon, 11 Jan 2021 22:57:23 +1100, Scott wrote:
> > > > Hi all,
> > > > 
> > > > I posted this on the forums and was unsuccessful so I thought I'd try here:
> > > > 
> > > > I've been struggling to pass additional arguments to the Prometheus 
> > > > node_exporter daemon in /etc/rc.conf.
> > > > 
> > > > The help for node_exporter provides an example argument (mount points to 
> > > > ignore) as:
> > > > 
> > > > --collector.filesystem.ignored-mount-points="^/(dev)($|/)"
> > > >                                 Regexp of mount points to ignore for filesystem collector.
> > > > 
> > > > The rc script says to use the _args variable to specify arguments to 
> > > > node_exporter:
> > > > # node_exporter_args (string):          Set extra arguments to pass to 
> > > > # Default is "".
> > > > 
> > > > Adding the line:
> > > > 
> > > > node_exporter_args="--collector.filesystem.ignored-mount-points=\"^/(dev)($|/)\""
> > > > 
> > > > to /etc/rc.conf and running sh -x /usr/local/etc/rc.d/node_exporter start 
> > > > results in:
> > > > 
> > > > + limits -C daemon su -m nobody -c 'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""'
> > > > 
> > > > Illegal variable name.
> > > > 
> > > > [...]
> > > > 
> > > > Can anyone please help?
> > > 
> > > If I see this correctly, the argument given to to the program's
> > > option --collector.filesystem.ignored-mount-points= is to be a
> > > regex, not the result of evaluating the regex (which the program
> > > surely does internally). So my suggestion, without knowing any
> > > further details, is to use this in /etc/rc.conf:
> > > 
> > > 	node_exporter_args='--collector.filesystem.ignored-mount-points="^/(dev)($|/)"'
> > > 
> > > Always remember that /etc/rc.conf is, more or less, just a simple
> > > shell script, so all rules applying to sh will apply to rc.conf
> > > exactly. That's why 'single quotes' will stop any expansion and
> > > transfer the value 1:1, which I think is what you are require to
> > > do here. Characters such as $, " or ^ will be part of the string
> > > handed over to the program, and will _not_ be interpreted by the
> > > shell prior to assigning to the _args variable.
> > > 
> > > Within "double quotes", symbols such as $ have a specific meaning,
> > > that's why you see the error ($ not properly quoted). So the
> > > error message is completely valid and logical - and expected. ;-)
> > > 
> > > [...]
> > > 
> > Thanks Poly,
> > 
> > here's what I get using:
> >         node_exporter_args='--collector.filesystem.ignored-mount-points="^/(dev)($|/)"'
> > 
> > + _doit=$' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""\''
> > + _run_rc_doit $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""\''
> > + debug $'run_rc_command: doit:  limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""\''
> > + eval $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""\''
> > + limits -C daemon su -m nobody -c 'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)($|/)""'
> > Illegal variable name.
> 
> So there seems to be another "layer" of possible interpretation.
> The call to sh contains still a single $ which leads to the error.
> Maybe using the quoted form \$ would help here?
> 
> 	node_exporter_args='--collector.filesystem.ignored-mount-points="^/(dev)(\$|/)"'
> 
> It's not entirely trivial to deal with several layers of
> variable expansion, especially when you want to avoid it. ;-)
> 
> Another option is to make the ' part of the option argument, but
> that would be quite ugly (and maybe doesn't work):
> 
> 	node_exporter_args="--collector.filesystem.ignored-mount-points='^/(dev)(\$|/)'"
> 
> Maybe you can try that as well?
> 
> 
> 
> 
> -- 
> Polytropon
> Magdeburg, Germany
> Happy FreeBSD user since 4.0
> Andra moi ennepe, Mousa, ...

Thanks again, but no luck:

with: node_exporter_args='--collector.filesystem.ignored-mount-points="^/(dev)(\$|/)"'
+ _doit=$' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\\$|/)""\''
+ _run_rc_doit $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\\$|/)""\''
+ debug $'run_rc_command: doit:  limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\\$|/)""\''
+ eval $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\\$|/)""\''
+ limits -C daemon su -m nobody -c 'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points="^/(dev)(\$|/)""'
Badly placed (.

with: node_exporter_args="--collector.filesystem.ignored-mount-points='^/(dev)(\$|/)'"

+ _doit=$' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points=\'^/(dev)($|/)\'"\''
+ _run_rc_doit $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points=\'^/(dev)($|/)\'"\''
+ debug $'run_rc_command: doit:  limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points=\'^/(dev)($|/)\'"\''
+ eval $' limits -C daemon su -m nobody -c \'sh -c "/usr/sbin/daemon  -f -p /var/run/node_exporter.pid -T node_exporter     /usr/bin/env /usr/local/bin/node_exporter     --web.listen-address=:9100     --collector.textfile.directory=/var/tmp/node_exporter     --collector.filesystem.ignored-mount-points=\'^/(dev)($|/)\'"\''
eval: 1: Syntax error: "(" unexpected 

Scott



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