Using this repo, you can leverage nested namespaces to deploy an OVN cluster where outer namespaces represent a compute node -- aka OVN chassis. Inside each of these emulated chassis, we are then able to create inner namespaces to emulate something comparable to ports of a VM in a compute node.
For more details, take a look at this talk from the 2019 OVScon: Deploying multi chassis OVN using docker in docker by Numan Siddique, Red Hat: Slides Video
Step 1: Build the container images
By default, Docker is used (we can switch to Podman later):
sudo OVN_SRC_PATH=<path_t_ovn_src_folder> OVS_SRC_PATH=<path_to_ovs_src_folder> ./ovn_cluster.sh build
This will create 2 docker images
- ovn/cinc: base image that gives us the nesting capability
- ovn/ovn-multi-node: built on top of cinc where ovs+ovn is compiled and installed
Step 2: Start openvswitch in your host
In order to interconnect the containers that emulate the chassis, we need an underlay network. This step is what provides that.
sudo /usr/share/openvswitch/scripts/ovs-ctl --system-id=testovn start
Step 3: Start the ovn-fake-multinode
sudo ./ovn_cluster.sh start
Step 4: Stop the ovn-fake-multinode and tweak cluster as needed
sudo ./ovn_cluster.sh stop
# look for start-container and configure-ovn functions in
vi ./ovn_cluster.sh
# Go back to step 3 and have fun!
A port called ovnfake-ext is created in the fake underlay network as part of ovn_cluster.sh start. You can use that as an easy way of getting inside the cluster (via NAT in OVN). Look for ip netns add ovnfake-ext in ovn_cluster.sh. An example for doing that is shown here:
sudo ip netns exec ovnfake-ext bash
ip a
ip route
ping -i 1 -c 1 -w 1 172.16.0.110 >/dev/null && \
echo 'happy happy, joy joy' || echo sad panda
exit
To deploy a VM that automatically performs the steps above as part of it's provisioning, consider using Vagrantfile located in this repo.
git clone https://github.com/ovn-org/ovn-fake-multinode.git && \
cd ovn-fake-multinode && vagrant up && vagrant ssh