Take a look at Madison Kellys' various blog postings at alteeve.com.
She has a generally very good set of how to's on how to build a 2 node
cluster.
On 05/30/2018 10:32 AM, Cobin Bluth wrote:
Hello Libvirt Users,
I would like to setup a two node bare-metal cluster. I need to
guidance on the network configuration. I have attached a small
diagram, the same diagram can be seen here:
https://i.imgur.com/SOk6a6G.png
I would like to configure the following details:
- Each node has a DHCP enabled guest network where VMs will run. (eg,
*192.168.1.0/24 <http://192.168.1.0/24>* for Host1, and
*192.168.2.0/24 <http://192.168.2.0/24>* for Host2)
- Any guest in Host1 should be able to ping guests in Host2, and vice
versa.
- All guests have routes to reach the open internet (so that '*yum
update*' will work "out-of-the-box")
- Each node will be able to operate fully if the other physical node
fails. (no central DHCP server, etc)
- I would like to _add more physical nodes later_ when I need the
resources.
This is what I have done so far:
- Installed latest Ubuntu 18.04, with latest version of libvirt and
supporting software from ubuntu's apt repo.
- Each node can reach the other via its own eth0.
- Each node has a working vxlan0, which can ping the other via its
vxlan0, so it looks like the vxlan config is working. (I used *ip link
add vxlan0 type vxlan...*)
- Configured route on Host1 like so: *ip route add 192.168.2.0/24
<http://192.168.2.0/24> via 172.20.0.1*
- Configured route on Host2 also: *ip route add 192.168.1.0/24
<http://192.168.1.0/24> via 172.20.0.2*
- All guests on Host1 (and Host1) can ping eth0 and vxlan0 on Host2,
and vice versa, yay.
- Guests on Host1 _cannot_ ping guests on Host2, I suspect because the
the default NAT config of the libvirt network.
So, at this point I started to search for tutorials or more
information/documentation, but I am a little overwhelmed by the sheer
amount of information, as well as a lot of "stale" information on
blogs etc.
I have learned that I can *virsh net-edit default*, and then change it
to an "open" network:* <forward mode='open'/>*
After doing this, the guests cannot reach outside their own network,
nor reach the internet, so I assume that I would need to add some
routes, or something else to get the network functioning like I want
it. There is also *<forward mode="route"/>*, but I dont fully
understand the scenarios where one would need an *open* or a *route*
forward mode. I have also shied away from using openvswitch, and have
opted for ifupdown2.
(I have taken most of my inspiration from this blog post:
https://joejulian.name/post/how-to-configure-linux-vxlans-with-multiple-unicast-endpoints/ )
Some questions that I have for the mailing list, any help would be
greatly appreciated:
- Is my target configuration of a KVM cluster uncommon? Do you see
drawbacks of this setup, or does it go against "typical convention"?
- Would my scenario be better suited for an "*open*" network or a
"*route*" network?
- What would be the approach to complete this setup?
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Netvel Inc. || Cell: (416)806-0133
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