使用Patroni和HAProxy创建高可用的PostgreSQL集群

 操作系统：CentOS Linux release 7.6.1810 (Core)

node1:192.168.216.130 master

node2:192.168.216.132 slave

node3:192.168.216.136 haproxy

这里仅测试，所以只部署了一主一丛，适用与测试环境，生产环境建议postgres至少1主2从，3个etcd节点,2个haproxy+keepalive组成

一、首先在两个节点上安装postgres，下面以postgres9.5.19为例

1、添加RPM
yum install https://download.postgresql.org/pub/repos/yum/9.5/redhat/rhel-7-x86_64/pgdg-centos95-9.5-3.noarch.rpm
2、安装PostgreSQL 9.5
yum install postgresql95-server postgresql95-contrib
注意：本次实验我们这里只需要操作到第2步即可，初始化可以由patroni来替我们完成
3、初始化数据库
/usr/pgsql-9.5/bin/postgresql95-setup initdb
4、设置开机自启动
systemctl enable postgresql-9.5.service
5、启动服务
systemctl start postgresql-9.5.service
6、查看版本
psql --version

二、安装etcd服务

1、这里我只在node1单节点上安装，仅实验,未做分布式部署，如果集群部署可以参考博客etcd集群部署文章

yum install etcd -y
cp /etc/etcd/etcd.conf /etc/etcd/etcd.conf.bak
cd /etc/etcd/
[root@localhost etcd]# egrep ^[A-Z] ./etcd.conf
ETCD_DATA_DIR="/var/lib/etcd/node1.etcd"
ETCD_LISTEN_PEER_URLS="http://192.168.216.130:2380"
ETCD_LISTEN_CLIENT_URLS="http://192.168.216.130:2379,http://127.0.0.1:2379"
ETCD_NAME="node1"
ETCD_INITIAL_ADVERTISE_PEER_URLS="http://192.168.216.130:2380"
ETCD_ADVERTISE_CLIENT_URLS="http://192.168.216.130:2379"
ETCD_INITIAL_CLUSTER="node1=http://192.168.216.130:2380"
ETCD_INITIAL_CLUSTER_TOKEN="etcd-cluster"
ETCD_INITIAL_CLUSTER_STATE="new"

2、保存文件，然后重启etcd服务

systemctl restart etcd

3、查看ectd服务是否正常

 三、安装patroni,分别在node1和node2节点安装

1、安装patroni用到依赖包，这里通过pip安装patroni

yum install gcc
yum install python-devel.x86_64
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python get-pip.py
pip install psycopg2-binary
pip install patroni[etcd,consul]

2、验证patroni是否安装成功

 3、配置patroni，以下操作在node1中进行

mkdir /data/patroni/conf -p
cd /data/patroni/conf
yum install git
git clone https://github.com/zalando/patroni.git
cd /data/patroni/conf/patroni-master
cp -r postgres0.yml ../conf/

 4、编辑node1上的postgres0.yml文件

scope: batman
#namespace: /service/
name: postgresql0

restapi:
  listen: 192.168.216.130:8008
  connect_address: 192.168.216.130:8008
#  certfile: /etc/ssl/certs/ssl-cert-snakeoil.pem
#  keyfile: /etc/ssl/private/ssl-cert-snakeoil.key
#  authentication:
#    username: username
#    password: password

# ctl:
#   insecure: false # Allow connections to SSL sites without certs
#