[ovirt-users] dns vm and ovirt

[Nathanaël Blanchet]

Thanks for precious advices!

So  it means that people who thought about hosted engine feature didn't 
get into your philosophy of running the engine into a second datacenter


Le 16/03/2018 à 16:48, Christopher Cox a écrit :
> On 03/16/2018 07:58 AM, Nathanaël Blanchet wrote:
>> Hi all,
>>
>> I'd need some piece of good practice about dealing a DNS server in or 
>> out of ovirt.
>> Until now we never wanted to integrate the DNS vm into ovirt because 
>> of the strong dependency. if the DNS server fails for any reason, it 
>> becomes difficult ot join the webadmin (except with a static etc 
>> hosts) and the nodes may become unvailable if they had been 
>> configured with fqdn.
>> We could consider a DNS failover setup, but in a self hosted engine 
>> setup (and more globally an hyperconverged setup) , it doesn't make 
>> sense of setting up a stand alone DNS vm outside of ovirt.
>>
>> So what about imitating engine vm status in a hosted engine setup? Is 
>> there a way to install the DNS vm outside of ovirt but on the ovirt 
>> host (and why not in a HA mode)?
>> Second option could be installing the named service on the hosted 
>> engine vm?
>>
>> Any suggestion or return of experience would be much appreciated.
>>
>
> You are wise to think of this as a dependency problem.  When dealing 
> with any "in band" vs. "out of band" type of scenario you want to 
> properly address how things work "without" the dependency.
>
> So.. for example, you could maintain a static host table setup for 
> your ovirt nodes.  Thus, they could find each other without DNS. Also, 
> those nodes might have an external DNS configured for lookups 
> (something you don't own) just so things like updates can happen.
>
> There are risks to everything.  Putting key (normally) out of band 
> infrastructure into your oVirt, including the engine, always involves 
> more risk.
>
> With that said, if you think about you key infrastructure being as a 
> separate oVirt datacenter, it would have things like the "static host" 
> maps and such.  Some of the infrastructure VMs housed there could 
> include the engine for the "general" datacenters (the ones not 
> providing VMs for key infrastructure).  This these "general" purpose 
> datacenters would house the normal VMs and use potentially VMs out of 
> the "infrastructure" datacenter.  Does that make sense?
>
> It's not unlike how a lot of cloud providers operate.  In fact, one 
> well known provider used to house their core cloud infrastructure in 
> VMware and use "cheaper" hypervisors for their cloud clients.
>
> Summary:
> static confs for infrastructure ovirt datacenter containing key core 
> infrastructure VMs (including things like DNS, DHCP, Active Directory, 
> and oVirt engines) used by general purpose ovirt datacenters.
>
> Obviously the infrastructure datacenter becomes very important, much 
> like your base network and should be thought of as "first" priority, 
> much like the network.  And much like the network, depends on some 
> kickstarter static configs.
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-- 
Nathanaël Blanchet

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