[lxc-devel] Integration Kubernetes and LXD/LXC

[Oliver Schad]

On Tue, 02 Oct 2018 11:29:30 +0200
Free Ekanayaka <free.ekanayaka at canonical.com> wrote:

> Oliver Schad <oliver.schad at automatic-server.com> writes:
> > If the container layer is unstable, you can't build a stable
> > service on top of it.  
> 
> How does LXE solve the issue of undesired restarts? I imagine that the
> restarts are triggered by the k8s control plane by connecting to the
> kubelet which in turns triggers some imperative CRI API which says
> "Please restart this pod". If that's the case, does LXE somehow ignore
> the restart request? I'm confused about this part.

It's true, that Kubelet does sometimes stuff which it shouldn't do and
we filter some things from Kubelet. The imperative nature of CRI is bad
in fact.

But: it really makes a difference, if sometimes Kubelet is wrong with
some things or the container engine itself creates problems (in case of
restart, update, too much logs, ...).

If the container engine dies for whatever reason in case of LXD,
nothing happens. If Docker dies, all container dies. If Kubelet creates
trouble, we're able to try to work around that problem with filtering.
We saw and see a lot of restarts of Docker.

In the area of platform services, it's hard to work one process
containers. And in the area of platform services it's hard to kill your
container, just because of updating a file. Both requirements you have
especially for stateful services. Avoid restart as much as you can and
if you have to restart something: do it in a planned/controlled way,
with fine grained options (i.e. notify other cluster members about a
node restart).

Best Regards
Oli

-- 
Automatic-Server AG •••••
Oliver Schad
Geschäftsführer
Turnerstrasse 2
9000 St. Gallen | Schweiz

www.automatic-server.com | oliver.schad at automatic-server.com
Tel: +41 71 511 31 11 | Mobile: +41 76 330 03 47
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