Re: Upgrade packages - Control Instance

On 21/05/2019 12:09, Christoph Berg wrote:
> Re: Sébastien Lardière 2019-05-21 <f4efadb7-ecb0-ba1f-383b-b9a38f988f87@lardiere.net>
>> Hi,
>>
>> I'm looking for a way to control the way instances are restarted when
>> `apt upgrade` run => sometime, if there is a large number of packages to
>> upgrade, the instances is stopped for a long time.
>>
>> In the past, I used to use start.conf with manual setting, then restart
>> "manually" after the upgrade, which give downtime as short as I can ;
>> but now, it seems that "stop" is always done, even when i disable the
>> systemd service (ok,it is weird to disable service and to want the
>> service up, I know ) => I think that the fact we can't forbid the stop
>> is not correct.
>>
>> I know that I can hold the postgresql packages, run the big `apt
>> upgrade` then unhold packages and do the postgresql upgrade, but I think
>> it's a more complicated way to do it.
>>
>> Am I miss something ?
>>
>> Am I the only one disturbed by the fact that we can't forbid stop ?
> The generic solution is policy-rc.d:
>
> https://people.debian.org/~hmh/invokerc.d-policyrc.d-specification.txt
>
> Simple sample implementation:
>
> #!/bin/sh
>
> # policy-rc.d script for chroots.
> # Copyright (c) 2007 Peter Palfrader <peter@palfrader.org>
>
> test -f /etc/debian_chroot || exit 0
>
> while true; do
>   case "$1" in
>     -*)         shift ;;
>     makedev)    exit 0;;
>     *)
>       echo "Not running services in chroot."
>       exit 101
>       ;;
>   esac
> done
>

Indeed, it works, I just added :

      postgresql*)
          echo "Do not manage PostgreSQL service"
          exit 101
          ;;

to manage postgresql specifically. The path is /usr/sbin/policy-rc.d ;
then chmod a+x

thanks,

--

Sébastien