[systemd-devel] Requires and After

[Reindl Harald]

Am 01.01.19 um 20:24 schrieb Tomasz Torcz:
> On Tue, Jan 01, 2019 at 08:20:19PM +0100, Olaf van der Spek wrote:
>> On Tue, Jan 1, 2019 at 8:17 PM Ian Pilcher <arequipeno at gmail.com> wrote:
>>>
>>> On 1/1/19 5:44 AM, Jérémy Rosen wrote:
>>>> The short answer is that Requires without after makes little sense,
>>>> since you can't reliably know if your dependency is here without it
>>>> (if it fails at startup, you might or might not be started, depending
>>>> on the startup order systemd chooses)
>>>
>>> There are cases where it makes sense.  For example, most OpenStack
>>> services require both a message bus and a database, but they are smart
>>> enough to wait and re-attempt their connections if either of those
>>> services isn't immediately available.
>>
>> What's the benefit of not having After= for those services?
> 
> I guess they can start and do their initialization in parallel with
> the service they require.

assumption or measured benefit?

most error handling for such cases has some sleep time which tyically
makes things slower than work with the initalization until everything is
in a proper state