Rich Freeman on 14 Jan 2015 06:39:47 -0800


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[PLUG] systemd presentation


Thanks to all who attended last night.  Slides for my presentation can
be found at:

https://docs.google.com/presentation/d/1YpW7h-sUSXtmroppd-S46dxtPYo3rcF32rh7vF99aVs/edit?usp=sharing

systemd offers a great deal of functionality, both in the core service
management component, and in everything else that it bundles.  Any of
these would be worthy of a talk of its own, though personally I've
really only scratched the surface with what you can do with systemd.
If there are talks that are of interest I'd be happy to try to put
something together, though I think in time there will be many systemd
experts within the group.

I strongly recommend reading many of the online blogs/docs/etc around
systemd.  Lennart's sysadmin blog series is particularly useful as it
illuminates many of the use cases that were envisioned for systemd.
Even for practical day-to-day administration I really only scratched
the surface with my talk.

For example, I didn't even tell you how to switch a running system to
single-user mode or another runlevel.  That is "systemctl isolate
rescue.target"  The isolate command tells the system to start the
named unit and its dependencies and stop everything else, and since
the unit is a target (a virtual unit) the result is that you end up in
that runlevel.  Another handy command is "systemctl default" which
tells systemd to isolate the default runlevel, which is very handy if
you had units fail on startup and you've fixed them or just want to
retry starting them.

There were some questions around using nspawn to run containers.  That
is definitely worth its own talk, but if you're interested I did blog
on this a while back:
https://rich0gentoo.wordpress.com/2014/07/14/quick-systemd-nspawn-guide/

That guide doesn't include enabling network namespaces.  I might just
go ahead and explain how to do that.  Right now I'm running a VPN
gateway in a container that has its own IPs (supported by iptables and
iproute2), which demonstrates that you can do quite a bit with them -
any host on my local network can use the VPN gateway.


--
Rich
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