[Pkg-sysvinit-devel] Bug#823680: systemd + unbound + resolvconf + squid3 == boot hangs: systemctl reload run on inactive service without --no-block

[Helmut Grohne]

Package: sysv-rc
Version: 2.88dsf-59
Severity: normal
File: /usr/sbin/invoke-rc.d

Hi,

If you install systemd, unbound, resolvconf and squid3 on jessie and
boot, system boot hangs. systemd starts unbound. unbound is started
properly and informs resolvconf about being a DNS server. resolvconf
runs the update-libc.d hook placed by squid3. squid3's resolvconf hook
runs "invoke-rc.d squid3 reload". invoke-rc.d runs "systemctl reload
squid3.service" and blocks, because squid3 isn't started yet. Eventually
unbound.service times out.

I argue that invoke-rc.d changed API. Formerly (with sysv) reloading a
service that isn't started would generally do nothing (or fail). In any
case, one generally wouldn't expect a reload operation to finish before
the invoke-rc.d call returns (as it often just sends a signal). With
systemd that changes to blocking.  This behaviour change is unexpected
and can break system boot.

Marco d'Itri recommeded adding --no-block to the systemctl invocation.
What do you think?

Helmut