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From Marcus Sorensen <shadow...@gmail.com>
Subject Re: [DISCUSS] OOM killer and Routing/System VM's = :(
Date Wed, 04 Sep 2013 21:35:49 GMT
What would work as a quick fix for this sort of situation would be if
the machine could be configured to power off rather than rebooting on
oom. Then the HA system would restart the VM, applying all configs.

Anyone know how to do that? :-)

On Wed, Sep 4, 2013 at 1:14 PM, Darren Shepherd
<darren.s.shepherd@gmail.com> wrote:
> On 09/04/2013 11:37 AM, Roeland Kuipers wrote:
>>
>> Hi Darren,
>>
>> Thanks for your reply! Could you share a bit more on your plans/ideas?
>>
>> We also have been braining on other approaches of managing the systemvm's,
>> especially small customizations for specific tenants. And maybe even
>> leveraging a config mgmt tools like chef or puppet with the ability to
>> integrate CS with that in some way.
>>
>
> I'll have to send the full details later but here's a rough idea.  The basic
> approach is this.  Logical changes to the VRs (or system vms in general) get
> mapped to configuration items.  So add a LB rule maps to iptables config and
> haproxy config.  When you change a LB rule we then bump up the requested
> version of the configuration for iptables/haproxy.  So the requested version
> will be 4 maybe.  The applied version will be 3 as the VR still has the old
> configuration.  Since 4 != 3, the VR will be signaled to pull the latest
> iptables/haproxy config.  So it will pull the configuration.  Say in the
> mean time somebody else adds four other LB rules.  So the requested version
> is now at 8.  So when the VR pulls the config it will get version 8, and
> then reply back saying it applied version 8.  The applied version is now 8
> which is greater than 4 (the version the first LB rule change was waiting
> for) so basically all async jobs waiting for the LB change will be done.
>
> To pull the configuration from the VR, the VR will be hitting a templating
> configuration system.  So it pulls the full iptables and haproxy config.
> Not incremental changes.
>
> So if the VR ever reboots itself, it can easily just pull the latest config
> of everything and apply it.  So it will be consistent.
>
> I'd be interested to hear what type of customizations you would like to add.
> It will definitely be an extensible system, but the problem is if your
> extensions wants to touch the same configuration files that ACS wants to
> manage.  That gets a bit tricky as its really easy for each to break each
> other.  But I can definitely add some hooks that users can use to mess up
> things and "void the warranty."
>
> I've thought about chef and puppet for this, but basically it comes down to
> two things.  I'm really interested in this being fast and light weight.
> Ruby is neither of those.  So the core ACS stuff will probably remain as
> very simple shell scripts.  Simple in that they really just need to download
> configuration and restart services.  They know nothing about the nature of
> the changes.  If, as an extension, you want to do something with puppet,
> chef, I'd be open to that.  That's your deal.
>
> This approach has many other benefits.  Like, for example, we can ensure
> that as we deploy a new ACS release existing system VMs can be updated
> (without a reboot, unless the kernel changes).  Additionally, its fast and
> updates happen in near constant time.  So most changes will be just a couple
> of seconds, even if you have 4000 LB rules.
>
> Darren
>

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