[Xymon] relocatable RPM or installing from source?

[J.C. Cleaver]

On Thu, February 25, 2016 12:53 pm, Jason Brockdorf wrote:
> Hello Xymon folks,
>
>
> I've been racking my brain about this lately and I don't see an easy way.
> I'd like to install the xymon client to /opt (or even the xymon server,
> but
> that's another problem) and I'm using the Terabithia RPMS.  I do have the
> option to install them in the regular FHS but then I have to depend our
> DCS
> vendor for any operations regarding the software, and with their track
> record, I'd rather not.  Additionally our current environment has the
> client
> installed in /opt in all of the existing servers (older client which will
> need to be upgraded as part of this project) and I'd like to stick with
> that
> convention, which was advised by my sysadmin, manager, and a colleague.
> It
> makes administration easier on us to stick with this convention.


A combination of relocation, EL7 (systemd), and the Terabithia 4.3 RPMs is
going to be tricky. xymon itself is written around the use of a home
directory, but the RPMs were built (at first) to specifically to rip a lot
of that out and use FHS locations instead :) So re-relocating after that
will be perilous.


Experimentally, I've built a version with relocations enabled for /usr/
/etc/ and /var/ on the client package (only), and uploaded this to
http://terabithia.org/rpms/xymon/testing/el7/* as 4.3.26-1.1 (I haven't
rebuilt the repo, so yum won't see it yet.)

This lets this command actually complete:
rpm --verbose --debug -ip --relocate /usr=/opt --relocate /etc=/opt/etc
--relocate /var=/opt/var xymon-client-4.3.26-1.1.el7.x86_64.rpm

... but as you've seen, that only changes where the files are placed, not
any of the configs, and it doesn't help with dependency tracking for yum.

To make a package install-relocatable, just add 'Prefix:' lines underneath
that %package heading. That tells rpm that those dirs can be moved.
+Prefix:                %{_prefix}
+Prefix:                %{_sysconfdir}
+Prefix:                %{_localstatedir}


> When I try to install them to a different root using YUM, it tries to
> install all of the dependencies as well.  Apparently there's no way to get
> YUM to ignore dependencies and if I try to install the RPM by relocating,

Right. If you're using yum --installroot, that's more for chroot type
environments, or installing over a separate mounted partition, than
enabling classical RPM relocation. yum doesn't really provide native
support for that.


> I
> get a message that the RPM is not relocatable.  So, I'm guessing I need to
> install from source or build my own package (yuck).
>
>
>
> So, I've installed from source on a test system, but then there's no
> scripts
> to create user accounts or add service definitions for starting/stopping
> the
> service.  I've found the runclient.sh script but I don't know how to adapt
> that to systemd on centos 7.

You can run
rpm -qp --scripts /path/to/your/xymon-4.3.26-1*rpm on an existing package
to see what exactly it's doing at install time for adding user accounts,
etc.

You *might* be able to stick the runclient.sh script into /etc/init.d/,
chkconfig --add it, and hope systemd handles it OK, but I'm not sure. To
get the sysvinit scripts in the package, you'll need to rebuild it using
"--without systemd". That should give you a result using the normal
sysvinit stuff.


>
> Can the Terabithia RPMs be made relocatable or does anyone advice on how
> to
> proceed?


For your client systems, unless you're using any of the Terabithia
features, I'd suggest distributing it as a tarball into /opt/ and using
runclient.sh or an init script that executes runclient.sh. That's the
quickest/easiest option.


If you need it in RPM form and are feeling experimental, add this to the
top of xymon.spec and do a rebuild of the SRPM:

%define _prefix /opt

This will likely have a greater chance of success than just a 'Prefix:
/opt' install relocation, but there are probably things that will still be
broken -- especially for the server side. (I would advise just using the
normal RPM on your Xymon Servers -- the file layout is going to be much
more complex there.)

If you can identify what breaks, though, that would be really helpful.
Redefining _prefix's and install relocations are some of those things that
are supposed to work in theory, but are rarely used and not very well
tested. They're officially discouraged in Fedora and other RPM-based
distros. That said, if there's better support that can be put into the RPM
to get closer to that ideal, I'd like to add it in...



(One of my goals in 4.4 is to significantly reduce the variation between
the source tarball and the RPMs and get rid of most of the workarounds
that are in place. That might mean more %post section config munging, or
more reliance on symlinks to simply place XYMONHOME locations in their
right spots and call it a day. This is an area of active work -- literally
just in the last few days -- but it's certainly not near production ready
yet.)


Hope this helps a little,

-jc