从主机访问Docker MySQL服务器，而不需要容器的IP地址

Question

I'm writing setup instructions for an application needing a MySQL database, and I'd like it to be easy even for people that don't have a MySQL installation.

Therefore, I'd like to run the MySQL server in a container:

docker run -p 3306:3306 \
    --name mysql \
    -e MYSQL_ROOT_PASSWORD=test \
    -e MYSQL_DATABASE=my_db \
    -d mysql

And to be able to connect to it this way:

mysql -u root -ptest -D my_db

Which doesn't work because the MySQL server only listens locally on the container.

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

So I see three options, none of which fitting my needs:

1) Using the container IP everytime

mysql -u root -ptest -D my_db -h 172.17.0.4

Annoying, the IP will often change and I don't want people to have to update their configuration this much.

2) Changing the configuration of MySQL inside the container

Requires to run a docker exec ... each time the container is run, so it's annoying as well.

3) Making a custom image where the configuration suits my needs

Seems a bit overkill, I'm pretty sure there is a better solution.

Thoughts?

Answer 1

When the mysql client is invoked as you did:

mysql -u root -ptest -D my_db

(ie without the hostname) or with localhost as hostname it tries to connect to the local server using Unix pipes. A pipe is a special file type and the client communicate with the server through it.

Your MySQL server is not local, it runs on a separate machine. You cannot connect to it using pipes.

As you already noticed, it works if you use the IP address of the container as argument for the -h command line option of mysql .

You also map the port 3306 of the container to port 3306 of the host machine. This means any TCP connection to port 3306 of the local machine goes through this mapping to the port 3306 of the container, where the MySQL server is listening.

Combining the two above, all you have to do is to put 127.0.0.1 as host name in the mysql command line:

mysql -u root -ptest -D my_db -h 127.0.0.1