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Installation and Configuration Options

In One-Click Installation we use the default configuration for installation. Kube-OVN also supports more custom configurations, which can be configured in the installation script, or later by changing the parameters of individual components. This document will describe what these customization options do, and how to configure them.

Built-in Network Settings

Kube-OVN will configure two built-in Subnets during installation:

  1. default Subnet, as the default subnet used by the Pod to assign IPs, with a default CIDR of 10.16.0.0/16 and a gateway of 10.16.0.1.
  2. The join subnet, as a special subnet for network communication between the Node and Pod, has a default CIDR of 100.64.0.0/16 and a gateway of 100.64.0.1.

The configuration of these two subnets can be changed during installation via the installation scripts variables:

POD_CIDR="10.16.0.0/16"
POD_GATEWAY="10.16.0.1"
JOIN_CIDR="100.64.0.0/16"
EXCLUDE_IPS=""

EXCLUDE_IP sets the address range for which kube-ovn-controller will not automatically assign from it, the format is: 192.168.10.20..192.168.10.30.

Note that in the Overlay case these two Subnets CIDRs cannot conflict with existing host networks and Service CIDRs.

You can change the address range of both Subnets after installation by referring to Change Subnet CIDR and Change Join Subnet CIDR.

Config Service CIDR

Since some of the iptables and routing rules set by kube-proxy will conflict with the rules set by Kube-OVN, Kube-OVN needs to know the CIDR of the service to set the corresponding rules correctly.

This can be done by modifying the installation script:

SVC_CIDR="10.96.0.0/12"

You can also modify the args of the kube-ovn-controller Deployment after installation:

args:
- --service-cluster-ip-range=10.96.0.0/12

Overlay NIC Selection

In the case of multiple NICs on a node, Kube-OVN will select the NIC corresponding to the Kubernetes Node IP as the NIC for cross-node communication between containers and establish the corresponding tunnel.

If you need to select another NIC to create a container tunnel, you can change it in the installation script:

IFACE=eth1

This option supports regular expressions separated by commas, e.g. 'ens[a-z0-9],eth[a-z0-9]'.

It can also be adjusted after installation by modifying the args of the kube-ovn-cni DaemonSet:

args:
- --iface=eth1

If each machine has a different NIC name and there is no fixed pattern, you can use the node annotation ovn.kubernetes.io/tunnel_interface to configure each node one by one. This annotation will override the configuration of iface.

kubectl annotate node no1 ovn.kubernetes.io/tunnel_interface=ethx

Config MTU

Since Overlay encapsulation requires additional space, Kube-OVN will adjust the MTU of the container NIC based on the MTU of the selected NIC when creating the container NIC. By default, the Pod NIC MTU is the host NIC MTU - 100 on the Overlay Subnet, and the Pod NIC and host NIC have the same MTU on the Underlay Subnet.

If you need to adjust the size of the MTU under the Overlay subnet, you can modify the parameters of the kube-ovn-cni DaemonSet:

args:
- --mtu=1333

Global Traffic Mirroring Setting

When global traffic mirroring is enabled, Kube-OVN will create a mirror0 virtual NIC on each node and copy all container network traffic from the current machine to that NIC， Users can perform traffic analysis with tcpdump and other tools. This function can be enabled in the installation script:

ENABLE_MIRROR=true

It can also be adjusted after installation by modifying the args of the kube-ovn-cni DaemonSet:

args:
- --enable-mirror=true

The ability to mirror traffic is disabled in the default installation, if you need fine-grained traffic mirroring or need to mirror traffic to additional NICs please refer to Traffic Mirror.

LB Settings

Kube-OVN uses L2 LB in OVN to implement service forwarding. In Overlay scenarios, users can choose to use kube-proxy for service traffic forwarding, in which case the LB function of Kube-OVN can be disabled to achieve better performance on the control plane and data plane.

This feature can be configured in the installation script:

ENABLE_LB=false

It can also be configured after installation by changing the args of the kube-ovn-controller Deployment:

args:
- --enable-lb=false

The LB feature is enabled in the default installation.

NetworkPolicy Settings

Kube-OVN uses ACLs in OVN to implement NetworkPolicy. Users can choose to disable the NetworkPolicy feature or use the Cilium Chain approach to implement NetworkPolicy using eBPF. In this case, the NetworkPolicy feature of Kube-OVN can be disabled to achieve better performance on the control plane and data plane.

This feature can be configured in the installation script:

ENABLE_NP=false

It can also be configured after installation by changing the args of the kube-ovn-controller Deployment:

args:
- --enable-np=false

NetworkPolicy is enabled by default.

EIP and SNAT Settings

If the EIP and SNAT capabilities are not required on the default VPC, users can choose to disable them to reduce the performance overhead of kube-ovn-controller in large scale cluster environments and improve processing speed.

This feature can be configured in the installation script:

ENABLE_EIP_SNAT=false

It can also be configured after installation by changing the args of the kube-ovn-controller Deployment:

args:
- --enable-eip-snat=false

EIP and SNAT is enabled by default. More information can refer to EIP and SNAT。

Centralized Gateway ECMP Settings

The centralized gateway supports two mode of high availability, primary-backup and ECMP. If you want to enable ECMP mode, you need to change the args of kube-ovn-controller Deployment:

args:
- --enable-ecmp=true

Centralized gateway default installation under the primary-backup mode, more gateway-related content please refer to Config Subnet.

Kubevirt VM Fixed Address Settings

For VM instances created by Kubevirt, kube-ovn-controller can assign and manage IP addresses in a similar way to the StatefulSet Pod. This allows VM instances address fixed during start-up, shutdown, upgrade, migration, and other operations throughout their lifecycle, making them more compatible with the actual virtualization user experience.

This feature is enable by default after v1.10.6. To disable this feature, you need to change the following args in the kube-ovn-controller Deployment:

args:
- --keep-vm-ip=false

CNI Settings

KBy default, Kube-OVN installs the CNI binary in the /opt/cni/bin directory and the CNI configuration file 01-kube-ovn.conflist in the /etc/cni/net.d directory. If you need to change the installation location and the priority of the CNI configuration file, you can modify the following parameters of the installation script.

CNI_CONF_DIR="/etc/cni/net.d"
CNI_BIN_DIR="/opt/cni/bin"
CNI_CONFIG_PRIORITY="01"

Or change the Volume mount and args of the kube-ovn-cni DaemonSet after installation:

volumes:
- name: cni-conf
  hostPath:
    path: "/etc/cni/net.d"
- name: cni-bin
  hostPath:
    path:"/opt/cni/bin"
...
args:
- --cni-conf-name=01-kube-ovn.conflist

Tunnel Type Settings

The default encapsulation mode of Kube-OVN Overlay is Geneve, if you want to change it to Vxlan or STT, please adjust the following parameters in the installation script:

TUNNEL_TYPE="vxlan"

Or change the environment variables of ovs-ovn DaemonSet after installation:

env:
- name: TUNNEL_TYPE
  value: "vxlan"

If you need to use the STT tunnel and need to compile additional kernel modules for ovs, please refer to Performance Tunning。

Please refer to Tunneling Protocol Selection for the differences between the different protocols in practice.

SSL Settings

The OVN DB API interface supports SSL encryption to secure the connection. To enable it, adjust the following parameters in the installation script:

ENABLE_SSL=true

The SSL is disabled by default.

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Last update: May 8, 2023
Created: June 30, 2022

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