Re: rc-init misunderstanding dependencies files

From: Eric Vidal <eric_at_obarun.org>
Date: Sun, 1 May 2016 14:01:36 +0400

> Within the examples, 00 is the root service that all other services
> depend on. Either through an explicit dependency call (like
> mount-proc) or through a bundle dependency (anything depending on
> ok-local will transitively depend on 00 since an explicit dependency
> on a bundle is an implicit dependency on every member of that bundle)

shame on me, i didn't seen the directory 00, i thought it was a special definition
This is clear now.... in theory ... i need a practice :) to understand correctly.

> A slight correction, rc-init doesn't run anything, it handles
> preparing the service tree. s6-rc change $SERVICE does the actual
> work. When s6-rc-compile packs the compiled form of the service
> directory it creates a stable ordering based on the dependency
> callouts. In the case of two services with equal weight (like if
> longrunA depends on oneshot1 and oneshot2, and both oneshots have no
> dependencies), s6-rc will run both nominally in parallel when it comes
> time to bring up the supervision tree. The only way to get the
> ordering that you describe, where s6-rc launches one service and then
> waits for the exit code before launching the second, is to have an
> explicit dependency called out in the second service.

understood

> > With this principle i can decide what service need to start first an another or after an another, right?
> For the most part yes. You can't have a service that says that it
> needs to run before another, but a dependency callout will guarantee
> that the listed services are started before the service defining those
> dependencies.

ok, i think the dependencies tree can be grow in complexity but with a practice it can be made.
Many thank

Regards

-- 
Eric Vidal <eric_at_obarun.org>
Received on Sun May 01 2016 - 10:01:36 UTC

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