[systemd-devel] Discrepancy in using dhclient b/w ubuntu 20.04 and ubuntu 16.04

[Reindl Harald]

Am 08.06.21 um 15:44 schrieb Aravindhan Krishnan:
> With all due respect, it would be very helpful if you can be a little 
> bit less snarky.

With all due respect, it would be very helpful not use reply-all and not 
convert each and every response to HTML

> i don't get the bash-nonsense for a handful of lines (most of them doing
> nothing at all) to begin with and given that there is no "Type=" in the
> unit file you may read the docs and try the different types
>  >> As per the man page 
> (https://man7.org/linux/man-pages/man5/systemd.service.5.html 
> <https://man7.org/linux/man-pages/man5/systemd.service.5.html>), the 
> default Type is simple if ExecStart is specified.

which means the prcoess is supposed to stay and not fork

> i also don't get the trial-binary
> why in the world don't you trhow away all that crap inlcuding the docker
> container and start dhclient at your own from a trivial systemd-unit?
>  >> As the name indicates it is a trial or minimalistic reproduction of 
> the issue we are seeing. Actual issue: We have a binary, which starts, 
> and stop dhclient on the interface on demand (Please don't come back 
> complaining why you would need to start and stop dhclient on demand). In 
> case the binary crashes for some unforeseen reason (which I had also 
> mentioned in my initial mail. 

this is handeled by systemd pretty fine - but not with an intermediate 
script and/or binary between

> why in the world don't you trhow away all that crap inlcuding the docker
> container and start dhclient at your own from a trivial systemd-unit?
>  >> Again, in a real-world scenario we support upto 1000+ vLANs. Running 
> 1000 different services for each of the dhclient could be too costly was 
> our initial assessment and thus we ran "dhclient <interface> -nw" from 
> the parent process. If you feel systemd can handle such higher loads, 
> without causing a high perf impact, it would be helpful as well

with your template service you have 1000 systemd services anyways but 
throw additional load on the machine with your monitoring binary which 
is monitored by systemd anyways

you gain nothing with all that wrappers