‘Managing a cluster’

クラスター情報

クラスターに関する情報を取得するには、 list またはtopology エンドポイントを使用します。

$ patronictl -c /etc/patroni.yml list
+ Cluster: demo-cluster-1 (7106835957012965359) ----+----+-----------+
| Member      | Host            | Role    | State   | TL | Lag in MB |
+-------------+-----------------+---------+---------+----+-----------+
| pg-patroni1 | xxx.xxx.xxx.xxx | Leader  | running |  1 |           |
| pg-patroni2 | xxx.xxx.xxx.xxx | Replica | running |  1 |         0 |
+-------------+-----------------+---------+---------+----+-----------+

$ patronictl -c /etc/patroni.yml topology
+ Cluster: demo-cluster-1 (7106835957012965359) ------+----+-----------+
| Member        | Host            | Role    | State   | TL | Lag in MB |
+---------------+-----------------+---------+---------+----+-----------+
| pg-patroni1   | xxx.xxx.xxx.xxx | Leader  | running |  1 |           |
| + pg-patroni2 | xxx.xxx.xxx.xxx | Replica | running |  1 |         0 |
+---------------+-----------------+---------+---------+----+-----------+

Patroniログ

Patroniログはsystemdによってシステムログに送信されます。 journalctl システムユーティリティを使用して取得します。

$ sudo journalctl -u patroni.service -n 100 -f
Jun 08 12:26:29 pg-patroni1 patroni[26589]: 2022-06-08 12:26:29,000 INFO: no action. I am (pg-patroni1), a secondary, and following a leader (pg-patroni2)
...

メンテナンスモード

クラスター管理を一時停止または再開するには、次を使用します。

$ patronictl -c /etc/patroni.yml pause
Success: cluster management is paused

$ patronictl -c /etc/patroni.yml list
+ Cluster: demo-cluster-1 (7106835957012965359) ----+----+-----------+
| Member      | Host            | Role    | State   | TL | Lag in MB |
+-------------+-----------------+---------+---------+----+-----------+
| pg-patroni1 | xxx.xxx.xxx.xxx | Leader  | running |  1 |           |
| pg-patroni2 | xxx.xxx.xxx.xxx | Replica | running |  1 |         0 |
+-------------+-----------------+---------+---------+----+-----------+
 Maintenance mode: on

$ patronictl -c /etc/patroni.yml resume
Success: cluster management is resumed

手動フェイルオーバーまたはスイッチオーバー

フェールオーバーエンドポイントを使用すると、正常なノードがない場合に手動フェールオーバーを実行できます。スイッチオーバーをスケジュールすることはできません。

Usage: patronictl failover [OPTIONS] [CLUSTER_NAME]

  Failover to a replica

Options:
  --master TEXT     The name of the current master
  --candidate TEXT  The name of the candidate
  --force           Do not ask for confirmation at any point
  --help            Show this message and exit.

スイッチオーバーエンドポイントは、クラスターが正常な場合、つまりリーダーがいる場合にのみ機能します。これにより、スイッチオーバーをスケジュールできます。

Usage: patronictl switchover [OPTIONS] [CLUSTER_NAME]

  Switchover to a replica

Options:
  --master TEXT     The name of the current master
  --candidate TEXT  The name of the candidate
  --scheduled TEXT  Timestamp of a scheduled switchover in unambiguous format
                    (e.g. ISO 8601)
  --force           Do not ask for confirmation at any point
  --help            Show this message and exit.

例：

$ patronictl -c /etc/patroni.yml switchover --candidate pg-patroni2
Master [pg-patroni1]:
When should the switchover take place (e.g. 2022-06-08T13:14 )  [now]:
Current cluster topology
+ Cluster: demo-cluster-1 (7106835957012965359) ----+----+-----------+
| Member      | Host            | Role    | State   | TL | Lag in MB |
+-------------+-----------------+---------+---------+----+-----------+
| pg-patroni1 | xxx.xxx.xxx.xxx | Leader  | running |  1 |           |
| pg-patroni2 | xxx.xxx.xxx.xxx | Replica | running |  1 |         0 |
+-------------+-----------------+---------+---------+----+-----------+
Are you sure you want to switchover cluster demo-cluster-1, demoting current master pg-patroni1? [y/N]: y
2022-06-08 12:14:48.01625 Successfully switched over to "pg-patroni2"
+ Cluster: demo-cluster-1 (7106835957012965359) ----+----+-----------+
| Member      | Host            | Role    | State   | TL | Lag in MB |
+-------------+-----------------+---------+---------+----+-----------+
| pg-patroni1 | xxx.xxx.xxx.xxx | Replica | stopped |    |   unknown |
| pg-patroni2 | xxx.xxx.xxx.xxx | Leader  | running |  1 |           |
+-------------+-----------------+---------+---------+----+-----------+

$ patronictl -c /etc/patroni.yml list
+ Cluster: demo-cluster-1 (7106835957012965359) ----+----+-----------+
| Member      | Host            | Role    | State   | TL | Lag in MB |
+-------------+-----------------+---------+---------+----+-----------+
| pg-patroni1 | xxx.xxx.xxx.xxx | Replica | running |  2 |         0 |
| pg-patroni2 | xxx.xxx.xxx.xxx | Leader  | running |  2 |           |
+-------------+-----------------+---------+---------+----+-----------+

$ patronictl -c /etc/patroni.yml history
+----+----------+------------------------------+----------------------------------+-------------+
| TL |      LSN | Reason                       | Timestamp                        | New Leader  |
+----+----------+------------------------------+----------------------------------+-------------+
|  1 | 67109024 | no recovery target specified | 2022-06-08T12:14:47.785857+00:00 | pg-patroni2 |
+----+----------+------------------------------+----------------------------------+-------------+