On Fri, Feb 04, 2011 at 06:17:30PM -0000, Clint Byrum wrote: > As far as the assertions, I think we have a method of making sure that > required files are there in the packaging system. The package upstart, > which owns /etc/init/rc-sysinit.conf, depends on mountall and ifupdown. > Further, there may be situations where something starts on an event that > is only generated by something it is not dependent on. For instance, you > may only want to run task foo when a service with NEEDS_FOO=1 starts.
Let me respectfully disagree in the case where files _must_ be present and events _must_ be asserted. If a file is accidentally removed, renamed, or becomes unaccessible _and_ is necessary for a successful boot, I want /bin/init or whatever to scream loud and long. The best place for that is in the *.conf stanza that depends upon the event that the missing file is supposed to assert. > The loose coupling gained by *not* making things too rigid is I think > part of the power of the system. Yes. Where events are optional, then we don't want hard checks. However if there was a double check on the file existing _and_ the event happening, then there would be an enforced documentation of both the event and where it was expected to come from, as a "good programming practice". More than one source of an event? Check for the existence of at least one of the source files or commands. > The 'emits' keyword is sort of like > assertions, but on the other side. Right now, there's no enforcement of > emits, so they're prone to rotting over time. All the more reason to have a programmed means to couple the emit with the event's sensitivity. - Let me say again that this whole mess makes me nervous. In the good old days if I could come up with a strictly sequential order of /etc/init.d/S[0-9][0-9]* scripts that worked reliably, I was done! It would work every time because A would be followed by B etc. all the way down to the end. Getting the strict relationship of all events and all dependencies correct is (for now) proving to be non-trivial. I suggest once more that having the _option_ of having a strictly sequential boot sequence for those of us that are not sensitive to how long it takes the machine to boot is _very_ desirable. Why is it desirable? Because I have been burned repeatedly by upstart and so I am still on Ubuntu 8.04. I understand /etc/init.d/S[0-9][0-9]* . I don't yet understand /etc/init/*.conf . Mike Bianchi -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/585908 Title: Document all events (was: cross-comment events and *.conf files) -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
