Kuryr Kubernetes OVN Integration

OVN provides virtual networking for Open vSwitch and is a component of the Open vSwitch project.

OpenStack can use OVN as its network management provider through the Modular Layer 2 (ML2) north-bound plug-in.

Integrating of OVN allows Kuryr to be used to bridge (both baremetal and nested) containers and VM networking in a OVN-based OpenStack deployment.

Testing with DevStack

The next points describe how to test OpenStack with OVN using DevStack. We will start by describing how to test the baremetal case on a single host, and then cover a nested environment where containers are created inside VMs.

Single Node Test Environment

  1. Create a test system.

    It’s best to use a throwaway dev system for running DevStack. Your best bet is to use latest Ubuntu LTS (20.04, Focal).

  2. Optionally create the stack user. You’ll need user account with passwordless sudo command.

    $ git clone https://opendev.org/openstack-dev/devstack.git
    $ sudo ./devstack/tools/create-stack-user.sh
    $ sudo su - stack
  3. Clone DevStack.

    $ sudo su - stack
    $ git clone https://opendev.org/openstack-dev/devstack.git
    $ git clone https://opendev.org/openstack/kuryr-kubernetes.git
  4. Configure DevStack to use OVN.

    kuryr-kubernetes comes with a sample DevStack configuration file for OVN you can start with. For example, you may want to set some values for the various PASSWORD variables in that file, or change the LBaaS service provider to use. Feel free to edit it if you’d like, but it should work as-is.

    $ curl https://opendev.org/openstack/kuryr-kubernetes/raw/branch/master/devstack/local.conf.sample \
      -o devstack/local.conf

    Note that due to OVN compiling OVS from source at /usr/local/var/run/openvswitch we need to state at the local.conf that the path is different from the default one (i.e., /var/run/openvswitch).

    Optionally, the ports pool functionality can be enabled by following: How to enable ports pool with devstack


    Kuryr-kubernetes is using OVN by default

  5. Run DevStack.

    This is going to take a while. It installs a bunch of packages, clones a bunch of git repos, and installs everything from these git repos.

    $ devstack/stack.sh

    Once DevStack completes successfully, you should see output that looks something like this:

    This is your host IP address:
    This is your host IPv6 address: ::1
    Keystone is serving at
    The default users are: admin and demo
    The password: pass
  6. Extra configurations.

    DevStack does not wire up the public network by default so we must do some extra steps for floating IP usage as well as external connectivity:

    $ sudo ip link set br-ex up
    $ sudo ip route add dev br-ex
    $ sudo ip addr add dev br-ex

    Then you can create forwarding and NAT rules that will cause “external” traffic from your instances to get rewritten to your network controller’s ip address and sent out on the network:

    $ sudo iptables -A FORWARD -d -j ACCEPT
    $ sudo iptables -A FORWARD -s -j ACCEPT
    $ sudo iptables -t nat -I POSTROUTING 1 -s -j MASQUERADE

Inspect default Configuration

In order to check the default configuration, in term of networks, subnets, security groups and loadbalancers created upon a successful DevStack stacking, you can check the Inspect default Configuration

Testing Network Connectivity

Once the environment is ready, we can test that network connectivity works among pods. To do that check out Testing Network Connectivity

Nested Containers Test Environment (VLAN)

Another deployment option is the nested-vlan where containers are created inside OpenStack VMs by using the Trunk ports support. Thus, first we need to deploy an undercloud DevStack environment with the needed components to create VMs (e.g., Glance, Nova, Neutron, Keystone, …), as well as the needed OVN configurations such as enabling the trunk support that will be needed for the VM. And then install the overcloud deployment inside the VM with the kuryr components.

Undercloud deployment

The steps to deploy the undercloud environment are the same described above for the Single Node Test Environment with the different of the sample local.conf to use (step 4), in this case:

$ curl https://opendev.org/openstack/kuryr-kubernetes/raw/branch/master/devstack/local.conf.pod-in-vm.undercloud.ovn.sample \
  -o devstack/local.conf

The main differences with the default ovn local.conf sample are that:

  • There is no need to enable the kuryr-kubernetes plugin as this will be installed inside the VM (overcloud).

  • There is no need to enable the kuryr related services as they will also be installed inside the VM: kuryr-kubernetes, kubelet, kubernetes-api, kubernetes-controller-manager, kubernetes-scheduler and kubelet.

  • Nova and Glance components need to be enabled to be able to create the VM where we will install the overcloud.

  • OVN Trunk service plugin need to be enable to ensure Trunk ports support.

Once the undercloud deployment has finished, the next steps are related to create the overcloud VM by using a parent port of a Trunk so that containers can be created inside with their own networks. To do that we follow the next steps detailed at Boot VM with a Trunk Port

Overcloud deployment

Once the VM is up and running, we can start with the overcloud configuration. The steps to perform are the same as without OVN integration, i.e., the same steps as for ML2/OVS:

  1. Log in into the VM:

    $ ssh -i id_rsa_demo ubuntu@FLOATING_IP
  2. Deploy devstack following steps 3 and 4 detailed at How to try out nested-pods locally (VLAN + trunk)

Testing Nested Network Connectivity

Similarly to the baremetal testing, we can create a demo deployment at the overcloud VM, scale it to any number of pods and expose the service to check if the deployment was successful. To do that check out Testing Nested Network Connectivity