Register mysql default logger prior to mysql#NewConfig()

[yhabteab]

Before:

2024-04-08T13:55:58.621+0200    WARN    database        Can't connect to database. Retrying     {"error": "driver: bad connection"}
2024-04-08T13:56:00.294+0200    WARN    database        Can't connect to database. Retrying     {"error": "dial tcp [::1]:3306: connect: connection refused"}
2024-04-08T13:56:40.352+0200    INFO    database        Reconnected to database {"after": "41.737475334s", "attempts": 10}
[mysql] 2024/04/08 14:03:19 connection.go:49: closing bad idle connection: EOF
[mysql] 2024/04/08 14:03:19 connection.go:49: closing bad idle connection: EOF

After:

2024-04-08T14:41:53.032+0200    DEBUG   database        [unexpected EOF]
2024-04-08T14:41:53.272+0200    DEBUG   database        [unexpected EOF]
2024-04-08T14:41:53.272+0200    WARN    database        Can't connect to database. Retrying     {"error": "driver: bad connection"}
2024-04-08T14:41:53.353+0200    DEBUG   database        [unexpected EOF]
2024-04-08T14:41:53.581+0200    DEBUG   database        [unexpected EOF]
2024-04-08T14:41:53.878+0200    DEBUG   database        [unexpected EOF]
...
2024-04-08T14:46:12.751+0200    DEBUG   database        [closing bad idle connection:  EOF]
2024-04-08T14:46:12.751+0200    DEBUG   database        [closing bad idle connection:  EOF]
2024-04-08T14:46:12.751+0200    DEBUG   database        [closing bad idle connection:  EOF]
2024-04-08T14:46:12.751+0200    DEBUG   database        [closing bad idle connection:  EOF]
2024-04-08T14:46:12.753+0200    DEBUG   database        [closing bad idle connection:  EOF]

[julianbrost]

Do we even care about the default logger? Currently, all it does is to set the public Logger attribute on the Config struct:

https://github.com/go-sql-driver/mysql/blob/4395c45fd098a81c5251667cda111f94c693ab14/errors.go#L53-L61
https://github.com/go-sql-driver/mysql/blob/4395c45fd098a81c5251667cda111f94c693ab14/dsn.go#L89
https://github.com/go-sql-driver/mysql/blob/4395c45fd098a81c5251667cda111f94c693ab14/dsn.go#L202-L204

Unfortunately, the documentation for SetLogger() doesn't explicitly state that there will never be logging outside of a connection:

SetLogger is used to set the default logger for critical errors. The initial logger is os.Stderr.

However, I think it's not totally unreasonable to assume that it stays this way (default logger kind of suggests that it just serves as the default for Config and even if it would change at some point in the future, it would be a bit annoying, but that's it).

I have the feeling that the default logger was only set as before #711, when the database was opened from a DSN, there was no other way to set a logger. So maybe we just want to change it and simply set config.Logger instead?

[oxzi]

I like the documentation 🥲

Logger               Logger            // Logger