Laurent Bercot <ska-devel@???> writes:
> On 24/09/2015 15:31, Rainer Weikusat wrote:
>> I'd still very much like to see an actual example which really needs
>> these depenencies which isn't either bogus or a workaround for a bug in
>> the software being managed.
>
> Your network must be up before you do any network connections.

Absolutely not. By the time some process wants to make a TCP connection
(example), there must be a way to transport/ route IP datagrams with a
given source address to a certain destination (address), otherwise,
establishing the connection will fail. This depends on the configuration
of the originating host and that of (typically) numerous other computers
'on the internet' and the configuration of each involved computer
including the originating host can change at any time. Hence 'failure'
is part of the normal mode of operation and proccesses trying to use TCP
need to deal with that. Possibly causes of 'failure' include some local
admin enabling, disabling or reconfiguring interfaces at run time.

> Your DNS cache must be up before any other service resolves names.

Same here: DNS must be available to resolve names via DNS, otherwise,
this won't work. But starting a recursive resolver before any daemon
which could want to resolve names does not guarantee this.

> Your filesystems must be mounted before you write to them.

That's slightly different because it's obviously not possible to start a
program stored in a file (which needs various other files to start)
before accessing any of these files is possible (it's still subject to
changes at runtime, though). But it's not necessary to declare a
dependency on "the filesystem" in a dozen different files and then run
some program in order to work out that "The filesystem namespace must be
constructed prior to using it!" (please note that I'm intentionally
ignoring NFS and such things --- network filesystems are a convenience
perversion and he who uses them deserves that his blood will be on his own
hands).