[Bug 701576] Re: Upstart should provide a generic network-services job for non-boot-critical network services to follow.
Clint Byrum
clint at fewbar.com
Sun Nov 3 20:21:51 UTC 2013
Excerpts from Dmitrijs Ledkovs's message of 2013-11-02 23:16:07 UTC:
> At the moment we guarantee that networking & local filesystems will be available when runlevel 2 (and similar) are emitted.
> Apart from rename, what other benefits does this semantic sugar bring?
>
First, job writers shouldn't need to be boot experts, so logically named
state tracking jobs make more sense than runlevels.
Second, this provides the ability to insert things into the stream rather
than add more parallelized actions to "runlevel 2".
Cron is a particular example where it is almost always better to start
cron as late as possible.
Consider this scenario:
[mysql.conf]
start on runlevel [2345]
[cron.conf]
start on runlevel [2345]
In this scenario, mysql is starting up in parallel with cron. Cron
is _much_ faster than mysql and so starts, and immediately runs its'
@reboot jobs which include Optimizing MySQL tables. This fails because
mysql is still coming up.
Now:
[mysql.conf]
start on starting network-services
[cron.conf]
start on started network-services
The ordering is achieved. cron is not started until mysql is started,
but they didn't have to explicitly state the relationship between cron
and mysql, it just makes logical sense.
It just means being able to order things based on this mostly generic
idea that most things are network services and thus would be migrated to
use the network-services job. If that works out, we can also have other
classes of jobs like security-services and login-services. Ideally we'd
be able to hide all of the nitty gritty plumbing events in these jobs so
that the general Upstart job reads more like a human thinks.
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https://bugs.launchpad.net/bugs/701576
Title:
Upstart should provide a generic network-services job for non-boot-
critical network services to follow.
Status in “upstart” package in Ubuntu:
Confirmed
Bug description:
Binary package hint: upstart
This is a feature request for the Ubuntu upstart package.
I posted the original description here:
https://lists.ubuntu.com/archives/ubuntu-
devel/2010-December/032254.html
The summary is that rather than require all upstart jobs to know when
exactly in the boot they want to start on and when exactly in the
shutdown they want to stop on, we should provide a readable, common
sense job whose started/stopping events can be followed, and whose
starting/stopped events can be used to prime and cleanup the
environment.
A merge proposal will follow the filing of this bug report.
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