dc connection handshake failed with mysql

[dongzl]

本地启动 Gaea OK，启动后使用 mycli 连接报如下错误：

(1105, 'unknown error: dc connection handshake failed with mysql')

mycli 连接：

mycli -h0.0.0.0 -utest -p1234 -P13306 db_kingshard

配置：

{
    "name": "test_kingshard_hash",
    "online": true,
    "read_only": false,
    "allowed_dbs": {
        "db_kingshard": true
    },
    "default_phy_dbs": {
        "db_kingshard": "db_kingshard"
    },
    "slow_sql_time": "1000",
    "black_sql": [
        ""
    ],
    "allowed_ip": null,
    "slices": [
        {
            "name": "slice-0",
            "user_name": "root",
            "password": "123456",
            "master": "127.0.0.1:3307",
            "slaves": [],
            "statistic_slaves": null,
            "capacity": 12,
            "max_capacity": 24,
            "idle_timeout": 60
        }
    ],
    "shard_rules": [
        {
            "db": "db_kingshard",
            "table": "shard_hash",
            "type": "hash",
            "key": "id",
            "locations": [
                2
            ],
            "slices": [
                "slice-0"
            ]
        }
    ],
    "users": [
        {
            "user_name": "test",
            "password": "1234",
            "namespace": "test_kingshard_hash",
            "rw_flag": 2,
            "rw_split": 1,
            "other_property": 0
        }
    ],
    "default_slice": "slice-0",
    "global_sequences": null
}

[xiyangxixian]

这个需要检查一下，后端数据库连接是否有权限连上呢

[dongzl]

这个需要检查一下，后端数据库连接是否有权限连上呢

你好，感谢回复，后端数据库没有问题，可以直接连接，我这里只有一个库，不分库只分表，不知道上面的配置是否有问题？

[doubility]

换个有主从配置的数据库

[Leadrive]

可能是mysql连接数不够造成的，增加max_connections

[hokyoDan]

我也遇到这个问题了，请问这个问题解决了吗

[julianzlzhang]

我也遇到这个问题，日志显示：
[2023-06-03 21:15:15] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/proxy/server.(*Session).Handshake:session.go:138] handleHandshakeResponse error, connId: 10005, err: ERROR 1045 (28000): Access denied for user 'admin'@'127.0.0.1:62258' (using password: Yes)
[2023-06-03 21:15:15] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/proxy/server.(*Server).onConn:server.go:128] [server] onConn error: ERROR 1045 (28000): Access denied for user 'admin'@'127.0.0.1:62258' (using password: Yes)
[2023-06-03 21:17:20] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/backend.(*Slice).GetConn:slice.go:84] get connection from slave failed, try to get from master, error: dc connection handshake failed with mysql
[2023-06-03 21:17:20] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/backend.(*Slice).GetConn:slice.go:92] get connection from backend failed, error: dc connection handshake failed with mysql
[2023-06-03 21:17:20] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/proxy/server.(*SessionExecutor).ExecuteSQL:executor.go:796] getUnShardConns failed: dc connection handshake failed with mysql
[2023-06-03 21:17:20] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/proxy/server.(*SessionExecutor).doQuery:executor_handle.go:107] execute select: dc connection handshake failed with mysql
[2023-06-03 21:17:20] [gaea_proxy] [Julian-M1-Pro.local] [WARN] [900000001] [github.com/XiaoMi/Gaea/proxy/server.(*Manager).RecordSessionSQLMetrics:manager.go:333] session error SQL, namespace: test_namespace_1, sql: select @@version_comment limit 1, cost: 33 ms, err: dc connection handshake failed with mysql
这里'admin'@'127.0.0.1:62258'是个啥？也没有用admin用户呀。

[Yinogi]

有同样的问题，我有两个namespace，一个后端数据库是5.6，另一个是5.7，都是单个服务没有主从，通过代理访问的时候5.6的报错了，writeHandshakeResponse41()执行完之后收到后端的响应头代码是ErrHeader（255），报错同1楼
后端5.7版本的数据库无任何问题，怀疑是版本兼容问题，本人golang不熟对MySQL协议研究也不深，楼主可以参考升级数据库，希望开发者能验证并确认下是否是版本兼容的问题

[Yinogi]

抓包看了下然后去查了下，网上说应该是版本兼容问题，但是不用代理可以直连，估计是代理的版本支持问题，不确定，希望有大佬指教
MySQL server 版本5.6.50

[Switch-vov]

我这边是8.0.22版本。打了断点看了下，MySQL报错Client does not support authentication protocol requested by server; consider upgrading MySQL client。

因为MySQL8.0之后，PLUGIN_AUTH默认是caching_sha2_password。
我把PLUGIN_AUTH改成mysql_native_password就能正常访问了。

ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY '123456';

[ryeLearnMore]

我也遇到了这个问题。但是应用接入后，只是偶尔报这种错，并不是直接拦截。看上面说是版本问题，那我这种零星报这种错误是什么原因呢？