Date: Mon, 11 Jan 2021 14:31:39 +0100 From: Polytropon <freebsd@edvax.de> To: Scott <freebsd-lists-5@thismonkey.com> Cc: freebsd-questions@freebsd.org Subject: Re: Need help specifying args in rc.conf for a service Message-ID: <20210111143139.278aec37.freebsd@edvax.de> In-Reply-To: <X/xKy6Y6Cl4%2Bzkhd@thismonkey.com> References: <X/w9IwVAFXyDr/ir@thismonkey.com> <20210111132107.82de40d0.freebsd@edvax.de> <X/xKy6Y6Cl4%2Bzkhd@thismonkey.com>
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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, ...
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