[Pkg-libvirt-maintainers] Bug#787973: Bug#787973: Please don't use systemctl status in postinst

[Guido Günther]

Hi,
On Sun, Jun 07, 2015 at 11:04:45AM +0200, Michael Biebl wrote:
> Package: libvirt-daemon-system
> Version: 1.2.16-2
> Severity: normal
> 
> Hi,
> 
> I noticed the following in postinst:
> 
>         # Force virtlockd to reexec if enabled
>         if [ -d /run/systemd/system ] && systemctl status virtlockd.service >/dev/null; then
>            systemctl reload virtlockd.service
>         fi
> 
> 
> using systemctl status is bad, since it accesses the journal, which can
> be quite costly.
> If you only want to test if a service is active, you can use
> systemctl is-active -q virtlockd.service, which is much more
> lightweight.
> The -q makes sure, you don't need to suppress stdout.
> 
> if [ -d /run/systemd/system ] && systemctl is-active -q virtlockd.service ; then
>            systemctl reload virtlockd.service
>         fi

Thanks for pointing this out. I went for the above solutine since ...

> 
> Or even simpler for your use case
>         if [ -d /run/systemd/system ] ; then
>            systemctl reload-or-try-restart -q virtlockd.service
>         fi

... returns 1 if the daemon is not running so we'd have to figure out
why non-zero is reported: failure to restart or not running at all.

> I think reload-or-try-restart does already exactly what you want.

See above but maybe I'm missing something.
Cheers,
 -- Guido

> 
> Cheers,
> Michael
> 
> -- System Information:
> Debian Release: stretch/sid
>   APT prefers unstable
>   APT policy: (500, 'unstable'), (500, 'stable'), (200, 'experimental')
> Architecture: amd64 (x86_64)
> Foreign Architectures: i386
> 
> Kernel: Linux 4.0.0-1-amd64 (SMP w/4 CPU cores)
> Locale: LANG=de_DE.utf8, LC_CTYPE=de_DE.utf8 (charmap=UTF-8)
> Shell: /bin/sh linked to /bin/dash
> Init: systemd (via /run/systemd/system)
> 
> Versions of packages libvirt-daemon-system depends on:
> ii  adduser              3.113+nmu3
> ii  gettext-base         0.19.4-1
> ii  init-system-helpers  1.23
> ii  libapparmor1         2.9.2-3
> ii  libaudit1            1:2.4-1+b1
> ii  libavahi-client3     0.6.31-5
> ii  libavahi-common3     0.6.31-5
> ii  libblkid1            2.26.2-6
> ii  libc6                2.19-18
> ii  libcap-ng0           0.7.6-1
> ii  libdbus-1-3          1.8.18-1
> ii  libdevmapper1.02.1   2:1.02.90-2.2
> ii  libgnutls-deb0-28    3.3.15-5
> ii  libnl-3-200          3.2.24-2
> ii  libnl-route-3-200    3.2.24-2
> ii  libnuma1             2.0.10-1
> ii  librados2            0.80.9-2
> ii  librbd1              0.80.9-2
> ii  libsasl2-2           2.1.26.dfsg1-13
> ii  libselinux1          2.3-2
> ii  libssh2-1            1.5.0-2+b1
> ii  libsystemd0          220-5~test0
> ii  libvirt-clients      1.2.16-2
> ii  libvirt-daemon       1.2.16-2
> ii  libvirt0             1.2.16-2
> ii  libxen-4.4           4.4.1-9
> ii  libxml2              2.9.2+dfsg1-3
> ii  libyajl2             2.1.0-2
> ii  logrotate            3.8.7-2
> ii  policykit-1          0.105-8
> 
> Versions of packages libvirt-daemon-system recommends:
> ii  bridge-utils  1.5-9
> ii  dmidecode     2.12-4
> ii  dnsmasq-base  2.72-3.1+b1
> ii  ebtables      2.0.10.4-3
> ii  iproute2      3.16.0-2
> ii  iptables      1.4.21-2+b1
> ii  parted        3.2-7
> pn  pm-utils      <none>
> 
> Versions of packages libvirt-daemon-system suggests:
> pn  apparmor    <none>
> pn  auditd      <none>
> ii  nfs-common  1:1.2.8-9
> ii  radvd       1:2.11-1
> ii  systemd     220-5~test0
> pn  systemtap   <none>
> 
> -- Configuration Files:
> /etc/libvirt/qemu.conf [Errno 13] Keine Berechtigung: u'/etc/libvirt/qemu.conf'
> /etc/libvirt/qemu/networks/default.xml [Errno 13] Keine Berechtigung: u'/etc/libvirt/qemu/networks/default.xml'
> 
> -- no debconf information
> 
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