Postgres 高可用集群 Yoke
Yoke 是 Postgres 的高可用集群，具有自动切换和自动集群恢复。Postgres冗余/自动故障转移解决方案，提供一个高可用PostgreSQL集群的简单管理。
Yoke 依赖：
*
包含 'primary', 'secondary' 和 'monitor' 三个节点的 3-server 集群
*
'primary' & 'secondary' 节点需要互相之间进行 ssh 连接 (w/o 密码)
*
'primary' & 'secondary' 节点需要远程同步安装 (或者一些替代 sync_command)
*
'primary' & 'secondary' 节点应该有安装 postgres，Yoke 会尝试调用 'postgres' 和 'pg_ctl'
*
'primary' & 'secondary' 节点作为一个子进程运行 postgres
配置示例：
[config]
# the IP which this node will broadcast to other nodes
advertise_ip=
# the port which this node will broadcast to other nodes
advertise_port=4400
# the directory where postgresql was installed
data_dir=/data
# delay before node decides what to do with postgresql instance
decision_timeout=30
# log verbosity (trace, debug, info, warn error, fatal)
log_level=warn
# REQUIRED - the IP:port combination of all nodes that are to be in the cluster (e.g. 'role=m.y.i.p:4400')
primary=
secondary=
monitor=
# SmartOS REQUIRED - either 'primary', 'secondary', or 'monitor' (the cluster needs exactly one of each)
role=
# the postgresql port
pg_port=5432
# the directory where node status information is stored
status_dir=./status
# the command you would like to use to sync the data from this node to the other when this node is master
sync_command=rsync -ae "ssh -o StrictHostKeyChecking=no" --delete {{local_dir}} {{slave_ip}}:{{slave_dir}}
[vip]
# Virtual Ip you would like to use
ip=
# Command to use when adding the vip. This will be called as {{add_command}} {{vip}}
add_command=
# Command to use when removing the vip. This will be called as {{remove_command}} {{vip}}
remove_command=
[role_change]
# When this nodes role changes we will call the command with the new role as its arguement '{{command}} {{(master|slave|single}))'
command=
