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How to use Open Virtual Networking with Kubernetes

On Linux, the easiest way to get started is to use OVN DaemonSet and Deployments.

Master Based Ovn-Kubernetes Images

With every PR that is merged into master, ovn-kubernetes images are automatically rebuilt and pushed to ghcr.io (i.e ovn-org's packages) for consumption. They are built with fedora, and ubuntu base images both of which are built for arm64 and amd64 architectures. These are not official releases and are just provided to make using ovn-kubernetes easier for other projects.

Install Open vSwitch kernel modules on all hosts.

Most Linux distributions come with Open vSwitch kernel module by default. You can check its existence with modinfo openvswitch. The features that OVN needs are only available in kernel 4.6 and greater. But, you can also install Open vSwitch kernel module from the Open vSwitch repository to get all the features OVN needs (and any possible bug fixes) for any kernel.

To install Open vSwitch kernel module from Open vSwitch repo manually, please read INSTALL.rst.

Run DaemonSet and Deployment

Create OVN StatefulSet, DaemonSet and Deployment yamls from templates by running the commands below: (The $MASTER_IP below is the IP address of the machine where kube-apiserver is running).

# Clone ovn-kubernetes repo
mkdir -p $HOME/work/src/github.com/ovn-org
cd $HOME/work/src/github.com/ovn-org
git clone https://github.com/ovn-org/ovn-kubernetes
cd $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/images
./daemonset.sh --image=docker.io/ovnkube/ovn-daemonset-u:latest \
    --net-cidr=192.168.0.0/16/24 --svc-cidr=172.16.1.0/24 \
    --gateway-mode="local" \
    --k8s-apiserver=https://$MASTER_IP:6443

Take note that the image docker.io/ovnkube/ovn-daemonset-u:latest is horribly outdated. You should build your own image and use that instead.

To set specific logging level for OVN components, pass the related parameter from the below mentioned list to the above command. Set values are the default values.

    --master-loglevel="5" \\Log level for ovnkube (master)
    --node-loglevel="5" \\ Log level for ovnkube (node)
    --dbchecker-loglevel="5" \\Log level for ovn-dbchecker (ovnkube-db)
    --ovn-loglevel-northd="-vconsole:info -vfile:info" \\ Log config for ovn northd
    --ovn-loglevel-nb="-vconsole:info -vfile:info" \\ Log config for northbound db
    --ovn-loglevel-sb="-vconsole:info -vfile:info" \\ Log config for southboudn db
    --ovn-loglevel-controller="-vconsole:info" \\ Log config for ovn-controller

If you are not running OVS directly in the nodes, you must apply the OVS Daemonset yaml.

kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/ovs-node.yaml

Apply OVN DaemonSet and Deployment yamls.

# Create OVN namespace, service accounts, ovnkube-db headless service, configmap, and policies
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/ovn-setup.yaml

# Optionally, if you plan to use the Egress IPs or EgressFirewall features, create the corresponding CRDs:
# create egressips.k8s.ovn.org CRD
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/k8s.ovn.org_egressips.yaml
# create egressfirewalls.k8s.ovn.org CRD
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/k8s.ovn.org_egressfirewalls.yaml

# Run ovnkube-db deployment.
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/ovnkube-db.yaml

# Run ovnkube-master deployment.
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/ovnkube-master.yaml

# Run ovnkube daemonset for nodes
kubectl create -f $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/yaml/ovnkube-node.yaml

NOTE: You don't need kube-proxy for OVN to work. You can delete that from your cluster.

Building the Daemonset container

Install build dependencies. If needed, create a softlink for pip to pip3:

ln -s $(which pip3) /usr/local/bin/pip

Now, clone the OVN Kubernetes repository, build the binaries, and build and push your image to your registry:

mkdir -p $HOME/work/src/github.com/ovn-org
cd $HOME/work/src/github.com/ovn-org
git clone https://github.com/ovn-org/ovn-kubernetes
cd $HOME/work/src/github.com/ovn-org/ovn-kubernetes/dist/images

# Build ovn docker image
pushd ../../go-controller
make
popd

# Build ovn kube image
# Find all built executables, but ignore the 'windows' directory if it exists
find ../../go-controller/_output/go/bin/ -maxdepth 1 -type f -exec cp -f {} . \;
echo "ref: $(git rev-parse  --symbolic-full-name HEAD)  commit: $(git rev-parse  HEAD)" > git_info

Now, build the image with:

OVN_IMAGE=<registry>/ovn-daemonset-f:latest
docker build -t $OVN_IMAGE -f Dockerfile.fedora . 
docker push $OVN_IMAGE
# or for buildah/podman:
# buildah bud -t $OVN_IMAGE -f Dockerfile.fedora .
# podman push $OVN_IMAGE

Docs overview

General

OVN overlay network on Openshift describes how an OVN overlay network is setup on Openshift 3.10 and later. It explains the various components and how they come together to establish the OVN overlay network. People that are interested in understatnding how the ovn cni plugin is installed will find this useful.

CI Tests describes how OVN-Kubernetes runs E2E tests, how to update the set of tests that run and how to run these tests locally.

OVN kubernetes KIND Setup. KIND (Kubernetes in Docker) deployment of OVN kubernetes is a fast and easy means to quickly install and test kubernetes with OVN kubernetes CNI. The value proposition is really for developers who want to reproduce an issue or test a fix in an environment that can be brought up locally and within a few minutes.

Debugging OVN

The golang based ovn kubernetes go-controller is a reliable way to deploy the OVN SDN using kubernetes clients and watchers based on golang. Contains ovnkube and ovn-k8s-cni-overlay build and usage instructions.

Installation/configuration

Installing OVS and OVN on Ubuntu both from packages and source

SSL This document explains the way one could use SSL for connectivity between OVN components.

ovn-northd SSL If the ovn-northd instance is not running on the same node as OVN NB and OVN SB database, then you will need to follow this doc to secure the communication between ovn-northd and NB/SB databases.

Config variables The config file contains common configuration options shared between the various ovn-kubernetes programs (ovnkube, ovn-k8s-cni-overlay, etc). This doc describes how to override the default values for some config options.

How to use Open Virtual Networking with Kubernetes (manual installation).

Features

Egress Firewall The EgressFirewall feature enables a cluster administrator to limit the external hosts that a pod in a project can access. The EgressFirewall object rules apply to all pods that share the namespace with the egressfirewall object.

Hybrid Overlay feature creates VXLAN tunnels to nodes in the cluster that have been excluded from the ovn-kubernetes overlay using the no-hostsubnet-nodes config option. These tunnels allow pods on ovn-kubernetes nodes to communicate directly with other pods on nodes that do not run ovn-kubernetes.

OVN multicast enables data to be delivered to multiple IP addresses simultaneously. For this to happen, the 'receivers' join a multicast group, and the sender(s) send data to it.

NetworkPolicy features and examples. By default the network traffic from and to K8s pods is not restricted in any way. Using NetworkPolicy is a way to enforce network isolation of selected pods.

OVS Hardware Offload. The OVS software based solution is CPU intensive, affecting system performance and preventing fully utilizing available bandwidth. OVS 2.8 and above support new feature called OVS Hardware Offload which improves performance significantly. This feature allows to offload the OVS data-plane to the NIC while maintaining OVS control-plane unmodified.

OVN central database High-availability OVN architecture has two central databases that can be clustered. The databases are OVN_Northbound and OVN_Southbound. This document explains how to cluster them and start various daemons for the ovn-kubernetes integration.

External IP and LoadBalancer Ingress OVN Kubernetes implements both External IPs and LoadBalancer Ingress IPs in the form of highly available OVN load balancers. It is the administrator's responsibility to route traffic to the Kubernetes nodes for both of these VIP types.

Other

Unit test mocks

ovnkube-trace a tool to trace packet simulations between points in an ovn-kubernetes driven cluster.

OVN Kubernetes Basics

A good resource to get started with understanding ovn-kubernetes is the following recording and slides, which run through the basic architecture and functionality of the system. slides recording