os: centos 7.4
postgresql: 9.6.9
etcd: 3.2.18
patroni: 1.4.4

本篇blog介绍下 etcd + patroni 发生切换时使用 callback 来重新设定 master 的 vip。
主要是方便自有机房或托管的，云环境貌似不能绑定固定的vip。

patroni 的一些参数

官方文档描述在callback时又这几个状态：

on_reload: run this script when configuration reload is triggered.
on_restart: run this script when the cluster restarts.
on_role_change: run this script when the cluster is being promoted or demoted.
on_start: run this script when the cluster starts.
on_stop: run this script when the cluster stops.

# su - postgres
$ vi /usr/patroni/conf/patroni_postgresql.ymlpostgresql:callbacks:on_start: /usr/patroni/conf/patroni_callback.shon_stop: /usr/patroni/conf/patroni_callback.shon_role_change: /usr/patroni/conf/patroni_callback.sh

patroni_callback.sh

这个脚本的作用就是，当本地postgresql变为 master 时，就绑定vip，变为slave时，就删除vip。

# cd /usr/patroni/conf/
# vi patroni_callback.sh#!/bin/bashreadonly cb_name=$1
readonly role=$2
readonly scope=$3function usage() {echo "Usage: $0 <on_start|on_stop|on_role_change> <role> <scope>";exit 1;
}echo "this is patroni callback $cb_name $role $scope"case $cb_name inon_stop)sudo ip addr del 192.168.56.100/24 dev enp0s8 label enp0s8:1   #sudo arping -q -A -c 1 -I enp0s8 192.168.56.100sudo iptables -F;;on_start);;on_role_change)if [[ $role == 'master' ]]; thensudo ip addr add 192.168.56.100/24 brd 192.168.56.255 dev enp0s8 label enp0s8:1sudo arping -q -A -c 1 -I enp0s8 192.168.56.100sudo iptables -Felif [[ $role == 'slave' ]]||[[ $role == 'replica' ]]||[[ $role == 'logical' ]]; thensudo ip addr del 192.168.56.100/24 dev enp0s8 label enp0s8:1   #sudo arping -q -A -c 1 -I enp0s8 192.168.56.100sudo iptables -Ffi;; *)usage;;
esac

修改ip后，一定要使用 arping

配置 sudo

# visudo
postgres ALL=(ALL) NOPASSWD:ALL

更改权限

# chown -R postgres:postgres /usr/patroni/conf/*
# ls -l
total 8
-rwxr--r-x 1 postgres postgres  768 Aug  8 18:59 patroni_callback.sh
-rw-r--r-- 1 postgres postgres 1616 Aug  8 18:44 patroni_postgresql.yml

参考：
https://postgresconf.org/system/events/document/000/000/228/Patroni_tutorial_4x3-2.pdf