Open Stack

Hi Serg,

Thank you for sharing this information :)

If I'm understanding correctly, the main reason you're using a
non-clustered / corosync setup is because that's how most other components
in Mirantis OpenStack are configured? Is there anything to be aware of in
how Murano communicates over the agent/engine rmq in a clustered rmq setup?

Also, is it safe to say that communication between agent/engine only, and
will only, happen during app deployment? Meaning, if the rmq server goes
down (let's even say it goes away permanently for exaggeration), short of
some errors in the agent log, nothing else bad will come out of it?

With regard to a different port and a publicly accessible address, I agree
and we'll be deploying this same way.

One thing we just ran into, though, was getting the agent/engine rmq config
to work with SSL. For some reason the murano/openstack configuration (done
via oslo) had no problems recognizing our SSL cert, but the agent/engine
did not like it at all. The Ubuntu Cloud packages have not been updated for
a bit so we ended up patching for the "insecure" option both in engine and
agent templates (btw: very nice that the agent can be installed via
cloud-init -- I really didn't want to manage a second set of images just to
have the agent pre-installed).

Thank you again,
Joe

On Thu, Sep 22, 2016 at 10:13 PM, Serg Melikyan <smelikyan at mirantis.com>
wrote:

> Hi Joe,
>
> I can share some details on how murano is configured as part of the
> default Mirantis OpenStack configuration and try to explain why it's
> done in that way as it's done, I hope it helps you in your case.
>
> As part of Mirantis OpenStack second instance of the RabbitMQ is
> getting deployed specially for the murano, but it's configuration is
> different than for the RabbitMQ instance used by the other OpenStack
> components.
>
> Why to use separate instance of the RabbitMQ?
>      1. Prevent possibility to get access to the RabbitMQ supporting
> whole cloud infrastructure by limiting access on the networking level
> rather than rely on authentication/authorization
>      2. Prevent possibility of DDoS by limiting access on the
> networking level to the infrastructure RabbitMQ
>
> Given that second RabbitMQ instance is used only for the murano-agent
> <-> murano-engine communications and murano-agent is running on the
> VMs we had to make couple of changes in the deployment of the RabbitMQ
> (bellow I am referencing RabbitMQ as RabbitMQ instance used by Murano
> for m-agent <-> m-engine communications):
>
> 1. RabbitMQ is not clustered, just separate instance running on each
> controller node
> 2. RabbitMQ is exposed on the Public VIP where all OpenStack APIs are
> exposed
> 3. It's has different port number than default
> 4. HAProxy is used, RabbitMQ is hidden behind it and HAProxy is always
> pointing to the RabbitMQ on the current primary controller
>
> Note: How murano-agent is working? Murano-engine creates queue with
> uniq name and put configuration tasks to that queue which are later
> getting picked up by murano-agent when VM is booted and murano-agent
> is configured to use created queue through cloud-init.
>
> #1 Clustering
>
> * Given that per 1 app deployment from we create 1-N VMs and send 1-M
> configuration tasks, where in most of the cases N and M are less than
> 3.
> * Even if app deployment will be failed due to cluster failover it's
> can be always re-deployed by the user.
> * Controller-node failover most probably will lead to limited
> accessibility of the Heat, Nova & Neutron API and application
> deployment will fail regardless of the not executing configuration
> task on the VM.
>
> #2 Exposure on the Public VIP
>
> One of the reasons behind choosing RabbitMQ as transport for
> murano-agent communications was connectivity from the VM - it's much
> easier to implement connectivity *from* the VM than *to* VM.
>
> But even in the case when you are connecting to the broker from the VM
> you should have connectivity and public interface where all other
> OpenStack APIs are exposed is most natural way to do that.
>
> #3 Different from the default port number
>
> Just to avoid confusion from the RabbitMQ used for the infrastructure,
> even given that they are on the different networks.
>
> #4 HAProxy
>
> In case of the default Mirantis OpenStack configuration is used mostly
> to support non-clustered RabbitMQ setup and exposure on the Public
> VIP, but also helpful in case of more complicated setups.
>
> P.S. I hope my answers helped, let me know if I can cover something in
> more details.
> --
> Serg Melikyan, Development Manager at Mirantis, Inc.
> http://mirantis.com | smelikyan at mirantis.com
>
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