A practical record of an accident caused by MySQL startup

MySQL` starts with a port being listened to, but the service is not fully started.

background

When MySQL starts, it will initialize the database for the first time. After MySQL is fully started, it will initialize the database for the second time.

The first time you initialize the database, use --skip-networking (this option disables MySQL's TCP/IP connection method) to start MySQL for initialization.

After initialization is complete, restart MySQL with the --skip-networking option turned off.

The second time you initialize the database, you will set the root password.

How to determine whether MySQL has been fully started

Try to actively connect to MySQL. A successful connection indicates that the service has been fully started.

mysql -hlocalhost -P3306 -uroot

ACCIDENT

Since the above judgment method uses socket to connect to the database, but the first time only prohibits MySQL's TCP/IP connection method,

Therefore, the second database initialization may have been performed before the first database initialization was completed.

The second database initialization sets the root password earlier than the first database initialization, which causes the first initialization to fail because it cannot connect to the database.

Finally, the TCP/IP connection method was not enabled and the application could not connect to the database.

First modification

Use -h127.0.0.1 to connect to the database

mysql -h127.0.01 -P3306 -uroot

However, since the host of the root user is set to localhost, 127.0.0.1 is not allowed to connect, and the first modification fails.

Second revision

wait-for-it.sh 127.0.0.1:3306 --timeout=300

mysql -hlocalhost -P3306 -uroot

wait-for-it.sh is used to detect whether 127.0.0.1:3306 is in the listening state. If it is, it means that the first database initialization is completed.

Then use localhost to try to connect to the database.

Original link: k8scat.com/posts/wait-…

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