同事在 k8s 中建立了一組 MySQL Cluster (group replication)，

有個 MySQL Router 來負責導向主要節點，同時也加了一個 MySQL operator，

不太懂細節，不過還是把一些會用到的指令記錄一下吧～

要在 MySQL Operator 裡執行指令的話，

先用  

kubectl exec -it mysql-operator-xxx -- bash

接著執行  

平常不加  

要加  

像我在下面指定的是 MySQL Router 提供的節點：

$ mysqlsh --uri "root:password@innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306/mysql"

MySQL Shell 8.0.30

Copyright (c) 2016, 2022, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
Other names may be trademarks of their respective owners.

Type '\help' or '\?' for help; '\quit' to exit.
WARNING: Using a password on the command line interface can be insecure.
Creating a session to 'root@innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306/mysql'
Fetching schema names for autocompletion... Press ^C to stop.
Your MySQL connection id is 132
Server version: 8.0.30 MySQL Community Server - GPL
Default schema set to `mysql`.

連上之後，可以使用  

然後可以執行  

不過下面的例子裡，取得 cluster 物件失敗了，

因為當時的 MySQL cluster 整個有點壞掉，

這也是為什麼我需要進到 MySQL Operator 來除錯…

 MySQL  innodb-cluster-instances.com-mysqlha.svc.cluster.local:3306  mysql  JS > var cluster = dba.getCluster()
Dba.getCluster: This function is not available through a session to a standalone instance (metadata exists, instance belongs to that metadata, but GR is not active) (MYSQLSH 51314)

 MySQL  innodb-cluster-instances.com-mysqlha.svc.cluster.local:3306  mysql  JS > cluster.status();
TypeError: Cannot read property 'status' of undefined

無法取得正常執行狀態的 cluster 物件，

這時可以試著用  

這過程中可能會問你某些叢集中的機器是否要重新加入，

也有可能因為連線不上，而問你是否要移除某些機器，這些都要自己判斷～

以下面例子來說，因為我一開始用 mysqlsh 連上的機器，

不是叢集中保有最新資料的那台，所以它叫我換成最新的那台：

 MySQL  innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306  mysql  JS > var cluster = dba.rebootClusterFromCompleteOutage();
Restoring the cluster 'innodb_cluster' from complete outage...

The instance 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y

Could not open a connection to 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306': 'MySQL Error 2061: Could not open connection to 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306': Authentication plugin 'caching_sha2_password' reported error: Authentication requires secure connection.'
Would you like to remove it from the cluster's metadata? [y/N]: n

Dba.rebootClusterFromCompleteOutage: The active session instance (innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306) isn't the most updated in comparison with the ONLINE instances of the Cluster's metadata. Please use the most up to date instance: 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306'. (RuntimeError)

 MySQL  innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306  mysql  JS >
Bye!

依照指示，用 mysqlsh 重新連上有最新資料的節點：

$ mysqlsh --uri "root:password@innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306/mysql"

MySQL Shell 8.0.30

Copyright (c) 2016, 2022, Oracle and/or its affiliates.
Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
Other names may be trademarks of their respective owners.

Type '\help' or '\?' for help; '\quit' to exit.
WARNING: Using a password on the command line interface can be insecure.
Creating a session to 'root@innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306/mysql'
Fetching schema names for autocompletion... Press ^C to stop.
Your MySQL connection id is 169
Server version: 8.0.30 MySQL Community Server - GPL
Default schema set to `mysql`.

再跑一次  

這次有成功將叢集重新啟動了：

MySQL  innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > var cluster = dba.rebootClusterFromCompleteOutage();
Restoring the cluster 'innodb_cluster' from complete outage...

The instance 'innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was part of the cluster configuration.
Would you like to rejoin it to the cluster? [y/N]: y

Could not open a connection to 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306': 'MySQL Error 2061: Could not open connection to 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306': Authentication plugin 'caching_sha2_password' reported error: Authentication requires secure connection.'
Would you like to remove it from the cluster's metadata? [y/N]: n

Validating instance configuration at innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306...

This instance reports its own address as innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306

Instance configuration is suitable.
* Waiting for seed instance to become ONLINE...
innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306 was restored.
Rejoining 'innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' to the cluster.
Validating instance configuration at innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306...

This instance reports its own address as innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306

Instance configuration is suitable.
Rejoining instance 'innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' to cluster 'innodb_cluster'...

Re-creating recovery account...
NOTE: User 'mysql_innodb_cluster_1001'@'%' already existed at instance 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306'. It will be deleted and created again with a new password.
The instance 'innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was successfully rejoined to the cluster.

The cluster was successfully rebooted.

退出 mysqlsh，重新再連上 MySQL Router 節點：

mysqlsh --uri "root:password@innodb-cluster.test-mysqlha.svc.cluster.local:3306/mysql"

現在可以用正常的方法取得 cluster 物件，並查看狀態。

以下例來說，它有發現 innodb-cluster-0 和 innodb-cluster-1 這兩個節點沒有註冊，

而 innodb-cluster-2 這個節點離線了 (整組都壞了…)：

 MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > var cluster = dba.getCluster()
 MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > cluster.status()
{
    "clusterName": "innodb_cluster",
    "defaultReplicaSet": {
        "name": "default",
        "primary": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
        "ssl": "VERIFY_IDENTITY",
        "status": "OK_NO_TOLERANCE_PARTIAL",
        "statusText": "Cluster is NOT tolerant to any failures. 1 member is not active.",
        "topology": {
            "innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "instanceErrors": [
                    "NOTE: instance server_id is not registered in the metadata. Use cluster.rescan() to update the metadata."
                ],
                "memberRole": "SECONDARY",
                "mode": "R/O",
                "readReplicas": {},
                "recovery": {
                    "state": "ON"
                },
                "recoveryStatusText": "Distributed recovery in progress",
                "role": "HA",
                "status": "RECOVERING",
                "version": "8.0.30"
            },
            "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "instanceErrors": [
                    "WARNING: The replication recovery account in use by the instance is not stored in the metadata. Use Cluster.rescan() to update the metadata."
                ],
                "memberRole": "PRIMARY",
                "mode": "R/W",
                "readReplicas": {},
                "replicationLag": "applier_queue_applied",
                "role": "HA",
                "status": "ONLINE",
                "version": "8.0.30"
            },
            "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "instanceErrors": [
                    "NOTE: group_replication is stopped."
                ],
                "memberRole": "SECONDARY",
                "memberState": "OFFLINE",
                "mode": "R/O",
                "readReplicas": {},
                "role": "HA",
                "status": "(MISSING)",
                "version": "8.0.30"
            }
        },
        "topologyMode": "Single-Primary"
    },
    "groupInformationSourceMember": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306"
}

執行  

可以把已經在叢集裡，但尚未存有相關 metadata 的新節點加進來：

MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > cluster.rescan();
Rescanning the cluster...

Result of the rescanning operation for the 'innodb_cluster' cluster:
{
    "name": "innodb_cluster",
    "newTopologyMode": null,
    "newlyDiscoveredInstances": [
        {
            "host": "innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
            "member_id": "5909e59c-8b48-11ed-8b88-0687c9d0276a",
            "name": null,
            "version": "8.0.30"
        }
    ],
    "unavailableInstances": [
        {
            "host": "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
            "label": "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
            "member_id": "fe619839-8692-11ed-84c7-aaa2840857fc"
        }
    ],
    "updatedInstances": []
}

A new instance 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was discovered in the cluster.
Would you like to add it to the cluster metadata? [Y/n]: y
Adding instance to the cluster metadata...
The instance 'innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was successfully added to the cluster metadata.

The instance 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' is no longer part of the cluster.
The instance is either offline or left the HA group. You can try to add it to the cluster again with the cluster.rejoinInstance('innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306') command or you can remove it from the cluster configuration.
Would you like to remove it from the cluster metadata? [Y/n]: n

至於離線或不在叢集裡的節點，

可以試試  

 MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > cluster.rejoinInstance('innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306')
Validating instance configuration at innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306...

This instance reports its own address as innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306

Instance configuration is suitable.
Rejoining instance 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' to cluster 'innodb_cluster'...

Re-creating recovery account...
NOTE: User 'mysql_innodb_cluster_1002'@'%' already existed at instance 'innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306'. It will be deleted and created again with a new password.
The instance 'innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306' was successfully rejoined to the cluster.

都完成後，再次試試  

再執行  

innodb-cluster-1 是 Primary 主節點，innodb-cluster-2 是副節點：

 MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > cluster.rescan();
Rescanning the cluster...

Result of the rescanning operation for the 'innodb_cluster' cluster:
{
    "name": "innodb_cluster",
    "newTopologyMode": null,
    "newlyDiscoveredInstances": [],
    "unavailableInstances": [],
    "updatedInstances": []
}

 MySQL  innodb-cluster.test-mysqlha.svc.cluster.local:3306 ssl  mysql  JS > cluster.status()
{
    "clusterName": "innodb_cluster",
    "defaultReplicaSet": {
        "name": "default",
        "primary": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
        "ssl": "VERIFY_IDENTITY",
        "status": "OK",
        "statusText": "Cluster is ONLINE and can tolerate up to ONE failure. 1 member is not active.",
        "topology": {
            "innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-0.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "memberRole": "SECONDARY",
                "mode": "R/O",
                "readReplicas": {},
                "recovery": {
                    "state": "ON"
                },
                "recoveryStatusText": "Distributed recovery in progress",
                "role": "HA",
                "status": "RECOVERING",
                "version": "8.0.30"
            },
            "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "memberRole": "PRIMARY",
                "mode": "R/W",
                "readReplicas": {},
                "replicationLag": "applier_queue_applied",
                "role": "HA",
                "status": "ONLINE",
                "version": "8.0.30"
            },
            "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306": {
                "address": "innodb-cluster-2.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306",
                "memberRole": "SECONDARY",
                "mode": "R/O",
                "readReplicas": {},
                "replicationLag": "applier_queue_applied",
                "role": "HA",
                "status": "ONLINE",
                "version": "8.0.30"
            }
        },
        "topologyMode": "Single-Primary"
    },
    "groupInformationSourceMember": "innodb-cluster-1.innodb-cluster-instances.test-mysqlha.svc.cluster.local:3306"
}

以上，就是這次使用 MySQL Shell 救援損毀的 MySQL Cluster 時，

有用到的一些指令囉～

參考資料：Restart Innodb MySQL Cluster after Complete outage(All node Down)