[collectd] exec plugin never runs, no errors reported

[Lonni J Friedman]

Hello,
I'm running collectd-5.8.0 on a Linux server.  I recently added an
Exec plugin which invokes a small python script that I wrote to
capture weather data.  If I run the script manually, it behaves as
expected, generating the following output over time:

$ /etc/collectd.d/get_weather.py
PUTVAL "hal/exec-weather/temperature-weather_level" interval=90 N:67.1
PUTVAL "hal/exec-weather/temperature-weather_level" interval=90 N:67.1
PUTVAL "hal/exec-weather/temperature-weather_level" interval=90 N:67.6


However, collectd never seems to run the plugin at all, and also isn't
generating any errors.  I'm logging everything from collectd into its
own dedicated log:

<Plugin logfile>
    LogLevel info
    File "/var/log/collectd.log"
    Timestamp true
    PrintSeverity true
</Plugin>

I have the following configured for the exec plugin:
<Plugin exec>
    Exec "netllama" "/etc/collectd.d/get_weather.py"
</Plugin>


When I (re)start collectd, I see the following in /var/log/collectd.log:

[2018-08-05 09:07:22] [info] plugin_load: plugin "exec" successfully loaded.

But no other messages related to the plugin, and the script itself is
not running.  At this point, I'm at a loss how to debug further when
nothing is being logged. Even if something was failing, shouldn't it
log something somewhere?

Thanks for any suggestions.