Varnish DAEMON_OPTS Options Errors-Collection of common programming errors

Even if Jacob will probably never read this, visitors from the future might appreciate what I’m going to write.

I believe I know what’s wrong, and it looks like a Debian-specific problem, at least verified on Ubuntu 11.04 and Debian Squeeze.

I traced the execution from my /etc/default/varnish that contains the $DAEMON_OPTS to the init script. In the init script /etc/init.d/varnish', thestart_varnishd()` function is:

start_varnishd() {
    log_daemon_msg "Starting $DESC" "$NAME"
    output=$(/bin/tempfile -s.varnish)
    if start-stop-daemon \
        --start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
        -P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1; then
        log_end_msg 0
    else
        log_end_msg 1
        cat $output
        exit 1
    fi
    rm $output
}

So I modified it to print the full start-stop-daemon command line, like:

 start_varnishd() {
    log_daemon_msg "Starting $DESC" "$NAME"
    output=$(/bin/tempfile -s.varnish)
+   echo "start-stop-daemon --start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- -P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1"
    if start-stop-daemon \
        --start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
        -P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1; then
        log_end_msg 0

So I got a command line echoed on STDOUT, and copied-pasted it into my shell. And, surprise! It worked. WTF?

Repeated again to be sure. Yes, it works. Mmh. Could it be another of those bash/dash corner cases? Let’s try feeding the start-stop-daemon command line to bash, and see how it reacts:

start_varnishd() {
    log_daemon_msg "Starting $DESC" "$NAME"
    output=$(/bin/tempfile -s.varnish)
    if bash -c "start-stop-daemon \
        --start --quiet --pidfile ${PIDFILE} --exec ${DAEMON} -- \
        -P ${PIDFILE} ${DAEMON_OPTS} > ${output} 2>&1"; then
        log_end_msg 0
    else
        log_end_msg 1
        cat $output
        exit 1
    fi
    rm $output
}

Yes, it works just fine, at least for my case. Here’s the relevant part of my /etc/default/varnish:

...
## Alternative 2, Configuration with VCL
#
# Listen on port 6081, administration on localhost:6082, and forward to
# one content server selected by the vcl file, based on the request.  Use a 1GB
# fixed-size cache file.
#
DAEMON_OPTS="-a :6081 \
             -T localhost:6082 \
             -f /etc/varnish/geoip-example.vcl \
             -S /etc/varnish/secret \
             -s malloc,100M \
             -p 'cc_command=exec cc -fpic -shared -Wl,-x -L/usr/include/GeoIP.h -lGeoIP -o %o %s'"
...

I’ve seen posts where someone tried to work around this problem by moving the compile command into a separated shell script. Unfortunately that doesn’t change the fact that start-stop-daemon is going to pass the $DAEMON_OPTS var through dash, and that will result in mangled options.

Would be something along the lines of:

-p 'cc_command=exec /etc/varnish/compile.sh %o %s'"

And then the compile.sh script as:

#!/bin/sh
cc -fpic -shared -Wl,-x -L/usr/include/GeoIP.h -lGeoIP -o $@

but it doesn’t work, so just patch your init scripts, and you’re good to go! Hope you can find this information useful.

Originally posted 2013-11-09 22:57:52.