jailed services dying

[Jan Bramkamp]

On 26.07.19 23:40, David Mehler wrote:

> Hello,
>
> I've got multiple service jails all on a single vps. One is a webserver
>   running apache 2.4 with php 7.3, the other is a mail server, a
> complete virtual mail hosting
>   setup with Postfix, Dovecot, Rspamd, the other is a database server
> running mysql, and I'm wanting to get shared
>   calendars in it in another setup running davical. I appear to be
> having a problem where ocationally a
>   jail service shuts down, for example the database, which shuts
>   everything else down because no service can access it, or the rspamd
> in the mail jail shuts down. These are all
>   on a single vps, a dual core I think, 4GB of ram, I'm wondering if i'm
>   hitting a resource bottleneck and if so how to determine it and to
>   limit the specific jail factor that is causing the issue?
>
> Any suggestions appreciated.
>
By default jails die with their last process. If you are running 
lightweight jails with just a single service inside them an the service 
dies for any reason the jail is destroyed as well. You can mark the 
jails as persistent to keep them around, but it wouldn't solve your real 
problem. Do you still have the /var/log/messages from around the time of 
the failure? As Allan Jude already mentions waking the OOM killer would 
be one possible explanation for the demise of your jails and I can 
attest from painful experience that the OOM killer has an uncanny knack 
for finding important processes e.g. the PostgreSQL or Postfix master 
processes.