[Pdns-users] What signal to tell PDNS to shut down?

[Brian Candler]

On 13/01/2019 18:27, Nick Williams wrote:
> I’m working on a Docker container to run my PDNS Authoritative 
> servers. I’m installing PDNS from repo.powerdns.com 
> <http://repo.powerdns.com>. The Docker command that is run in 
> `pdns_server`. The `docker stop` command sends a `SIGTERM` to PID 1, 
> waits some amount of time, and then sends SIGKILL to force it to stop. 
> It’s having to resort to SIGKILL, because `pdns_server` doesn’t 
> respond to `SIGTERM`. What is the correct signal to tell PDNS to shut 
> down?
The problem is not with pdns, it's with docker: strange things happen if 
you run the application as pid 1. For an explanation see: 
https://hackernoon.com/my-process-became-pid-1-and-now-signals-behave-strangely-b05c52cc551c 


Solution: run a different pid 1 process whose job it is to launch the 
application, such as tini:

https://github.com/krallin/tini

With a modern version of docker, tini is included.  Just use the --init 
flag to docker run, and it should all be fine.

Regards,

Brian.

P.S. You can easily show that pdns is happy with a SIGTERM when you run 
it outside of docker.

root at ns2:~# ps auxwww | grep pdns
pdns      1612  0.0  0.7 677608  8064 ?        Ssl   2018  16:37 
/usr/sbin/pdns_server --guardian=no --daemon=no --disable-syslog 
--write-pid=no
root     25477  0.0  0.0  12944   968 pts/0    S+   20:24   0:00 grep 
--color=auto pdns
root at ns2:~# kill -TERM 1612
root at ns2:~# ps auxwww | grep pdns
root     25486  0.0  0.0  12944   940 pts/0    S+   20:24   0:00 grep 
--color=auto pdns
root at ns2:~#

This is pdns-server 4.0.6 under Ubuntu 16.04, with mysql backend.

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