Debian上PostgreSQL如何實現高可用

在Debian上實現PostgreSQL的高可用性，可以采用多種策略和技術。以下是一些常見的方法：

1. 使用Patroni

Patroni是一個用于管理PostgreSQL高可用性的工具，它基于Pacemaker和Corosync來提供故障轉移和自動恢復功能。

安裝Patroni

sudo apt-get update
sudo apt-get install patroni

配置Patroni

創建一個Patroni配置文件/etc/patroni.yml，示例配置如下：

scope: postgres
namespace: /db/
name: postgres

restapi:
  listen: 0.0.0.0:8008
  connect_address: 127.0.0.1

etcd:
  host: 127.0.0.1:2379
  scheme: http

bootstrap:
  dcs:
    ttl: 30
    loop_wait: 10
    retry_timeout: 10
    maximum_lag_on_failover: 1048576
    postgresql:
      use_pg_rewind: true
      use_slots: true
      parameters:
        wal_level: replica
        max_wal_senders: 4
        wal_keep_segments: 8
        hot_standby: on

postgresql:
  listen: 0.0.0.0:5432
  connect_address: 127.0.0.1
  data_dir: /var/lib/postgresql/12/main
  pg_hba:
  - host replication replicator 127.0.0.1/32 md5
  - host all all 0.0.0.0/0 md5
  authentication:
    replication:
      username: replicator
      password: your_replicator_password
    superuser:
      username: postgres
      password: your_superuser_password

tags:
  nofailover: false
  noloadbalance: false
  clonefrom: false
  nosync: false

啟動Patroni

sudo patroni /etc/patroni.yml

2. 使用Pgpool-II

Pgpool-II是一個中間件，可以提供負載均衡、故障轉移和高可用性。

安裝Pgpool-II

sudo apt-get update
sudo apt-get install pgpool2

配置Pgpool-II

編輯/etc/pgpool2/pgpool.conf文件，示例配置如下：

backend_hostname0 = 'localhost'
backend_port0 = 5432
backend_weight0 = 1
backend_data_directory0 = '/var/lib/postgresql/12/main'
backend_flag0 = 'ALLOW_TO_FAILOVER'

backend_hostname1 = 'localhost'
backend_port1 = 5433
backend_weight1 = 1
backend_data_directory1 = '/var/lib/postgresql/12/main'
backend_flag1 = 'ALLOW_TO_FAILOVER'

load_balance_mode = on
health_check_period = 10
health_check_timeout = 10
master_slave_mode = on
master_slave_sub_mode = 'stream'
failover_command = '/usr/lib/postgresql/12/bin/pg_ctl promote -D /var/lib/postgresql/12/main'

啟動Pgpool-II

sudo systemctl start pgpool2

3. 使用Keepalived

Keepalived可以提供虛擬IP地址和故障轉移功能。

安裝Keepalived

sudo apt-get update
sudo apt-get install keepalived

配置Keepalived

編輯/etc/keepalived/keepalived.conf文件，示例配置如下：

vrrp_instance VI_1 {
    state MASTER
    interface eth0
    virtual_router_id 51
    priority 100
    advert_int 1

    authentication {
        auth_type PASS
        auth_pass your_password
    }

    virtual_ipaddress {
        192.168.1.100
    }
}

virtual_server 192.168.1.100 5432 {
    delay_loop 6
    lb_algo rr
    lb_kind DR
    nat_mask 255.255.255.0
    persistence_timeout 50
    protocol TCP

    real_server 192.168.1.101 5432 {
        weight 1
        TCP_CHECK {
            connect_timeout 10
            connect_port 5432
        }
    }

    real_server 192.168.1.102 5432 {
        weight 1
        TCP_CHECK {
            connect_timeout 10
            connect_port 5432
        }
    }
}

啟動Keepalived

sudo systemctl start keepalived

總結

以上方法各有優缺點，選擇哪種方法取決于你的具體需求和環境。Patroni提供了最全面的高可用性解決方案，而Pgpool-II和Keepalived則更適合特定的場景。在實際部署時，建議進行充分的測試和驗證。