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ovn kubernetes go-controller

The golang based ovn controller is a reliable way to deploy the OVN SDN using kubernetes clients and watchers based on golang.

Build

Ensure go version >= 1.16

cd go-controller
make clean
make

Then find the executables here : go-controller/_output/go/bin/

'ovnkube' is the single all-in-one executable useful for deploying the ovn cni plugin for a kubernetes deployment

'ovn-k8s-cni-overlay' is the cni executable to be placed in /opt/cni/bin (or another directory in which kubernetes will look for the plugin) so that it can be invoked for each pod event by kubernetes

To get the Windows version of 'ovnkube' and 'ovn-k8s-cni-overlay' run the following:

cd go-controller
make clean
make windows

Then find the executables here : go-controller/_output/go/windows/

Usage

Run the 'ovnkube' executable to initialize master, node(s) and as the central all-in-one controller that builds the network as pods/services/ingress objects are born in kubernetes. Options specified on the command-line override configuration file options which override environment variables. Environment variables override service account files.

Usage:
  -config-file string
     configuration file path (default: /etc/openvswitch/ovn_k8s.conf)
  -cluster-subnets string
     cluster wide IP subnet to use (default: 11.11.0.0/16)
  -init-master string
     initialize master which enables both cluster manager (allocates node subnets) and ovnkube controller (which watches pods/nodes/services/policies and creates OVN db resources), requires the hostname as argument
  -init-cluster-manager string
     initialize cluster manager that watches nodes (allocates subnet for each node from the cluster-subnets), requires the hostname as argument and doesn't connect to the OVN dbs.
  -init-ovnkube-controller string
     initialize ovnkube-controller (which watches pods/nodes/services/policies and create OVN db resources), requires the hostname as argument.
  -init-node string
     initialize node, requires the name that node is registered with in kubernetes cluster
  -cleanup-node string
     cleanup up OVS resources on the k8s node (after ovnkube-node daemonset deletion), requires the name that node is registered with in kubernetes cluster
  -remove-node string
     remove a node from the OVN cluster. Requires the name that node is
     registered with in kubernetes cluster
  -mtu int
     MTU value used for the overlay networks (default: 1400)
  -conntrack-zone int
     for gateway nodes, the conntrack zone used for conntrack flow rules (default: 64000)
  -loglevel int
     log verbosity and level: 5=debug, 4=info, 3=warn, 2=error, 1=fatal (default: 4)
  -logfile string
     path of a file to direct log output to
  -cni-conf-dir string
     the CNI config directory in which to write the overlay CNI config file (default: /etc/cni/net.d)
  -cni-plugin string
     the name of the CNI plugin (default: ovn-k8s-cni-overlay)
  -k8s-kubeconfig string
     absolute path to the Kubernetes kubeconfig file (not required if the --k8s-apiserver, --k8s-cacert, and --k8s-token are given)
  -k8s-apiserver string
     URL of the Kubernetes API server (not required if --k8s-kubeconfig is given) (default: http://localhost:8443)
  -k8s-cacert string
     the absolute path to the Kubernetes API CA certificate (not required if --k8s-kubeconfig is given)
  -k8s-token string
     the Kubernetes API authentication token (not required if --k8s-kubeconfig is given)
  -nb-address string
     IP address and port of the OVN northbound API (eg, ssl:1.2.3.4:6641).  Leave empty to use a local unix socket.
  -nb-client-privkey string
     Private key that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnnb-privkey.pem)
  -nb-client-cert string
     Client certificate that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnnb-cert.pem)
  -nb-client-cacert string
     CA certificate that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnnb-ca.cert)
  -sb-address string
     IP address and port of the OVN southbound API (eg, ssl:1.2.3.4:6642).  Leave empty to use a local unix socket.
  -sb-client-privkey string
     Private key that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnsb-privkey.pem)
  -sb-client-cert string
     Client certificate that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnsb-cert.pem)
  -sb-client-cacert string
     CA certificate that the client should use for talking to the OVN database.  Leave empty to use local unix socket. (default: /etc/openvswitch/ovnsb-ca.cert)

Environment Variables

Values for some configuration options can be passed in environment variables.

  -KUBECONFIG
     absolute path to the Kubernetes kubeconfig file overridden by --k8s-kubeconfig
  -K8S_APISERVER
     URL of the Kubernetes API server overriden by --k8s-apiserver
  -K8S_CACERT
     the absolute path to the Kubernetes API CA certificate overriden by --k8s-cacert
  -K8S_TOKEN
     the Kubernetes API authentication token overriden by --k8s-token

Service Account Files

The cluster makes the serviceaccount ca.crt and token available in files that are mounted in each container.

  -/var/run/secrets/kubernetes.io/serviceaccount/ca.crt
     contains the Kubernetes API CA certificate overriden by --k8s-cacert and K8S_CACERT.
  -/var/run/secrets/kubernetes.io/serviceaccount/token
     contains the Kubernetes API token overriden by --k8s-token and K8S_TOKEN

Configuration File

Generic configuration options (those common between master, node, and gateway modes) can also be specified in the configuration file. The default configuration file path is /etc/openvswitch/ovn_k8s.conf but can be changed with the -config-file option. Options specified in the config file override defautl values, but are themselves overridden by command-line options.

Example configuration file

[default]
mtu=1500
conntrack-zone=64321

[kubernetes]
apiserver=https://1.2.3.4:6443
token=TG9yZW0gaXBzdW0gZG9sb3Igc2l0IGFtZXQsIGNvbnNlY3RldHVyIGFkaXBpc2NpbmcgZWxpdC4gQ3JhcyBhdCB1bHRyaWNpZXMgZWxpdC4gVXQgc2l0IGFtZXQgdm9sdXRwYXQgbnVuYy4K
cacert=/etc/kubernetes/ca.crt

[logging]
loglevel=5
logfile=/var/log/ovnkube.log

[cni]
conf-dir=/etc/cni/net.d
plugin=ovn-k8s-cni-overlay

[ovnnorth]
address=ssl:1.2.3.4:6641
client-privkey=/path/to/private.key
client-cert=/path/to/client.crt
client-cacert=/path/to/client-ca.crt
server-privkey=/path/to/private.key
server-cert=/path/to/server.crt
server-cacert=path/to/server-ca.crt

[ovnsouth]
<same as ovn north>

Example

Initialize the master (both cluster manager and ovnkube controller)

ovnkube --init-master <master-host-name> \
	--k8s-cacert <path to the cacert file> \
	--k8s-token <token string for authentication with kube apiserver> \
	--k8s-apiserver <url to the kube apiserver e.g. https://10.11.12.13.8443> \
	--cluster-subnets <cidr representing the global pod network e.g. 192.168.0.0/16>

The aforementioned master ovnkube controller will enable both the cluster manager (which watches nodes and allocates node subnets) and ovnkube controller which initialize the central master logical router and establish the watcher loops for the following:

  • nodes: as new nodes are born and init-node is called, the logical switches will be created automatically by giving out IPAM for the respective nodes
  • pods: as new pods are born, allocate the logical port with dynamic addressing from the switch it belongs to
  • services/endpoints: as new endpoints of services are born, create/update the logical load balancer on all logical switches
  • network policies and a few other k8s resources

Initialize the cluster manager and ovnkube controller separately

ovnkube --init-cluster-manager <master-host-name> \
	--k8s-cacert <path to the cacert file> \
	--k8s-token <token string for authentication with kube apiserver> \
	--k8s-apiserver <url to the kube apiserver e.g. https://10.11.12.13.8443> \
	--cluster-subnets <cidr representing the global pod network e.g. 192.168.0.0/16>

The aforementioned ovnkube cluster manager will establish the watcher loops for the following:

  • nodes: as new nodes are born and init-node is called, the subnet IPAM is allocated for the respective nodes
ovnkube --init-ovnkube-controller <master-host-name> \
	--k8s-cacert <path to the cacert file> \
	--k8s-token <token string for authentication with kube apiserver> \
	--k8s-apiserver <url to the kube apiserver e.g. https://10.11.12.13.8443> \
	--cluster-subnets <cidr representing the global pod network e.g. 192.168.0.0/16>

The aforementioned ovnkube controller will initialize the central master logical router and establish the watcher loops for the following:

  • nodes: as new nodes are born and init-node is called, the logical switches will be created automatically by giving out IPAM for the respective nodes
  • pods: as new pods are born, allocate the logical port with dynamic addressing from the switch it belongs to
  • services/endpoints: as new endpoints of services are born, create/update the logical load balancer on all logical switches
  • network policies and a few other k8s resources

Initialize a newly added node for the OVN network

Remember to install the cni binary first. Use the Makefile, or, manually copy 'ovn-k8s-cni-overlay' to /opt/cni/bin (or the appropriate directory that kubernetes will use to look for the plugin).

make install

Then, run the ovnkube executable to initalize the node:

ovnkube --init-node <name of the node as identified in kubernetes> \
	--k8s-cacert <path to the cacert file> \
	--k8s-token <token string for authentication with kube apiserver> \
	--k8s-apiserver <url to the kube apiserver e.g. https://10.11.12.13.8443>

With the above command, the node will get initialized for all OVN communication and a logical switch will be created for it.