Your message dated Wed, 18 Mar 2020 23:43:41 +0100
with message-id <[email protected]>
and subject line Re: Please provide database.target as a synchronization point
for applications providing databases and needing databases
has caused the Debian Bug report #861789,
regarding Please provide database.target as a synchronization point for
applications providing databases and needing databases
to be marked as done.
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861789: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=861789
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Package: mariadb-server-10.1
Version: 10.1.21-2
Severity: normal
I note in the postinst that it says
update-rc.d mysql defaults 19 21
with the explanation given in debian/rules that this is so the mysqld
server begins before apache. However, with dependency-based boot
systems (which current installations are by default), the "19 21" no
longer has any effect: insserv only looks at the dependency
information in its header. In fact, on my system, because of the
dependencies on the various init scripts (which are just the default
Debian ones), apache2 comes in at S04apache2 while mysql comes in at
S05mysql!
To specify that mysql really should start prior to apache2 (and
presumably nginx as well; not sure what other servers), you would need
lines:
X-Start-Before: apache2
X-Stop-After: apache2
in the header of /etc/init.d/mysql.
But I don't see any dependency of apache2 on mysqld in its normal
configuration, and if a particular installation of apache2 does
require mysqld to be started in advance, then it is up to the sysadmin
of that system to add:
Should-Start: mysql
Should-Stop: mysql
to their instance of /etc/init.d/apache2 (or whatever other
appropriate init.d file).
So my suggestion is just to drop the "19 21" from the debian/rules so
as not to give the false impression that mysql is starting earlier.
Best wishes,
Julian
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On Tue, 3 Sep 2019 13:53:08 +0200 Michael Biebl <[email protected]> wrote:
> Control: tags -1 + moreinfo
>
> On Thu, 4 May 2017 17:47:17 +0200 Christian Hofstaedtler
> <[email protected]> wrote:
> > How will a database.target solve anything in those not so uncommon
> > setups:
> >
> > - database is remote
> >
> > or
> >
> > - one database needs another to start?
> >
> > Please consider: if you end up with a solution that only works
> > for 90% of installations - fails on 10% - is that actually
> > solving your problem?
>
>
> I don't understand the use case here.
>
> Certainly, in a default apache and mysql configuration, there is no need
> to delay the start of apache and wait until mysql, mariadb or whatever
> other db has started (if multiple databases are installed, would we wait
> for one of them, all of them?)
> So introducing this artificial delay feels like a regression.
>
> If there there is the need to actually start apache after mysql due to
> how the system is configured for a specific use case, it's very easy to
> achieve that with systemd by creating a drop-in snippet.
>
> To pick up Christian's analogy:
> If such a database.target is not useful for 90% of its users and
> actually introduces artificial delays, does this relay outweigh the
> benefit for those 10% who might benefit from it?
>
> I feel like I need better arguments that such a target / synchronization
> point is a good idea.
> Especially, how and by which packages such a target should be used (and
> this would probably need documentation as well)
My concerns are still the same as I outlined above, so I think such a
database.target would not be too useful given it would only be very
vaguely defined.
So my recommendation is to use such drop-in snippets to change the
ordering on a as-needed basis.
Regards,
Michael
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