[OPEN-ILS-DEV] On the merits of init scripts...

[Aaron Joyner]

I've recently started playing around with Evergreen.  Upon installing it on
a test machine, and having a power blip the next evening, it dawned on me
that there are no canned, ready-to-use, init scripts for starting the
OpenSRF services (the usual suspects of osrf_ctl.sh... start_all).  By
contrast, memcached, postgresql, and ejabberd are all taken care of by the
distribution packages, but none of the walk-throughs in the wiki mention an
init script, and there's not one readily available in subversion.  I had a
brief discussion w/ miker and dbs this evening on IRC with regards to why
that was, and there was some concerns about restarting a large production
environment automatically, and we all agreed that either something custom,
or perhaps even nothing at all, was the best way to proceed in a large
setting.  In the smaller case (testing and development machines, home
installs, etc) it seems practical to have something that will work almost
all of the time, and keep things in the expected state.

This raised a host of questions.

What should the init script be called?  OpenSRF, as it's starting OpenSRF
services (Router, Perl, C), or should it's name be 'evergreen', following a
system-oriented naming style instead, as the goal of the script after all is
to start up a workable Evergreen system?  Personally, I'd lean towards the
former, as Evergreen is really more than just the OpenSRF services, but it
may be counter-intuitive to some users.  As miker alluded to, perhaps a
wrapper script with analagous 'start|stop|restart' functionality would be
useful.  It could check to ensure the appropriate base services are running
(postgresql, a jabber server, memcached), perhaps by inspecting the configs
to determine everything is correct, and starting services as necessary?
Stop / restart would be a bit more tricky, as you wouldn't necessarily want
to stop postgresql on the server on a whim (especially on smaller
installations, it might be in use by another service).

Should there be just one relatively simple universal SysV-style init
script?  Should there also be multiple init scripts in the style of the
various distributions, which leverage additional management features
provided by those distributions?  Where's the point of diminishing return,
there?

I'll stop babbling now.  I'm exceedingly new to Evergreen, and readily
acknowledge that I don't know what's best here.  I'd love to hear the
insights from others on this list, and if a consensus approach can be found
I'll gladly code up something along those lines.

To kick off the discussion, how does a simplistic init script for OpenSRF
services, which accepts (start|stop|restart), and will likely work on all
SysV platforms sound as a starting point?  What other features would be
interesting for your use cases?

Respectfully,
Aaron S. Joyner
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