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=
