ceph-csi/vendor/k8s.io/kubernetes/pkg/proxy/ipvs/README.md

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2018-01-09 18:57:14 +00:00
# How to use IPVS
This document shows how to use kube-proxy ipvs mode.
## What is IPVS
**IPVS (IP Virtual Server)** implements transport-layer load balancing, usually called Layer 4 LAN switching, as part of
Linux kernel.
IPVS runs on a host and acts as a load balancer in front of a cluster of real servers. IPVS can direct requests for TCP
and UDP-based services to the real servers, and make services of real servers appear as irtual services on a single IP address.
## How to use
#### Load IPVS kernel modules
Currently the IPVS kernel module can't be loaded automatically, so first we should use the following command to load IPVS kernel
modules manually.
```shell
modprobe ip_vs
modprobe ip_vs_rr
modprobe ip_vs_wrr
modprobe ip_vs_sh
modprobe nf_conntrack_ipv4
```
After that, use `lsmod | grep ip_vs` to make sure kernel modules are loaded.
#### Run kube-proxy in ipvs mode
#### Local UP Cluster
Kube-proxy will run in iptables mode by default in a [local-up cluster](https://github.com/kubernetes/community/blob/master/contributors/devel/running-locally.md).
Users should export the env `KUBEPROXY_MODE=ipvs` to specify the ipvs mode before deploying the cluster if want to run kube-proxy in ipvs mode.
#### Cluster Created by Kubeadm
Kube-proxy will run in iptables mode by default in a cluster deployed by [kubeadm](https://kubernetes.io/docs/setup/independent/create-cluster-kubeadm/).
Since IPVS mode is still feature-gated, users should add the flag `--feature-gates=SupportIPVSProxyMode=true` in `kubeadm init` command
```
kubeadm init --feature-gates=SupportIPVSProxyMode=true
```
to specify the ipvs mode before deploying the cluster if want to run kube-proxy in ipvs mode.
If you are using kubeadm with a configuration file, you can specify the ipvs mode adding `SupportIPVSProxyMode: true` below the `featureGates` field.
Then the configuration file is similar to:
```json
kind: MasterConfiguration
apiVersion: kubeadm.k8s.io/v1alpha1
...
featureGates:
SupportIPVSProxyMode: true
...
```
#### Test
Use `ipvsadm` tool to test whether the kube-proxy start succeed. By default we may get result like:
```shell
# ipvsadm -ln
IP Virtual Server version 1.2.1 (size=4096)
Prot LocalAddress:Port Scheduler Flags
-> RemoteAddress:Port Forward Weight ActiveConn InActConn
TCP 10.0.0.1:443 rr persistent 10800
-> 10.229.43.2:6443 Masq 1 0 0
TCP 10.0.0.10:53 rr
UDP 10.0.0.10:53 rr
```