[Openstack] How to make DevStack install OpenStack with Neutron?

Mark Kirkwood mark.kirkwood at catalyst.net.nz
Tue Oct 7 06:23:36 UTC 2014

On 07/10/14 18:43, Mike Spreitzer wrote:
> Thanks, Mark.  OK, maybe I should say that I am past my first attempt,
> and am on to something a little more ambitious.  Following recipes like
> yours, and also ones from Sergey Kraynev, Salvatore Orlando, and Ian
> Choi, I am able to get DevStack to create an OpenStack installation with
> Neutron that works --- as long as I do not attempt any communication
> between the outside world and the VMs that I can create with that
> OpenStack.
> What I want is a local.conf or localrc that will cause DevStack to do a
> single-node install of OpenStack with Neutron (I am not picky about
> plugin or driver) on a host with one NIC, with the following property.
>   When I use that OpenStack to create a VM, and assign a floating IP to
> that VM, IP communication between that VM and machines in the wider
> world is possible.  By "the wider world" I mean the part of the internet
> with which the host can communicate, whatever that may be.  For example,
> if the host is a machine on the public internet, the wider world would
> be everything reachable on the public internet.  Another example was in
> my original question: the host is a lab machine on a 10... network (it
> has more than one subnet, connected by real layer 3 routers), and the
> wider world in that case is all the other machines in that lab.
> As best I can tell, this requires some correspondence between (a) the
> settings of FLOATING_RANGE and PUBLIC_NETWORK_GATEWAY that I put in
> localrc and (b) the pre-DevStack IP address, netmask, and gateway of the
> host.  Perhaps I am confused about something critical here.  I do not
> understand why nobody talks about this.  Is it because everybody is
> using the same Vagrant/VBox script and that happens to correspond with
> the DevStack defaults?

Sorry, yes makes sense.

I think why this is not documented is the usual use-case for devstack is 
development setups where real external ips for the VMs is usually not a 
point of interest.

For instance I never need this...I do sometimes want the VMs to be able 
to access the internet, and that is pretty easy:

$ sudo sysctl -w net.ipv4.ip_forward=1
$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

For access the other way, yes it's more complex. As others have posted, 
you need real ip ranges available in your external network and 
(probably) an additional nic in your test box that can be 
designated/mapped as br-ex
so that the various routers/gateways in the neutron setup use it.



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