Connect to mysql in a docker container from the host

Question

(It's probably a dumb question due to my limited knowledge with Docker or mysql administration, but since I spent a whole evening on this issue, I dare to ask it.)

In a nutshell

I want to run mysql in a docker container and connect to it from my host. So far, the best I have achieved is:

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

More details

I'm using the following Dockerfile:

FROM ubuntu:14.04.3
RUN apt-get update && apt-get install -y mysql-server

# Ensure we won't bind to localhost only
RUN grep -v bind-address /etc/mysql/my.cnf > temp.txt \
  && mv temp.txt /etc/mysql/my.cnf

# It doesn't seem needed since I'll use -p, but it can't hurt
EXPOSE 3306

CMD /etc/init.d/mysql start && tail -F /var/log/mysql.log

In the directory where there is this file, I can succesfully build the image and run it with:

> docker build -t my-image .
> docker run -d -p 12345:3306 my-image

When I attach to the image, it seems to work just fine:

# from the host
> docker exec -it <my_image_name> bash

#inside of the container now
$ mysql -u root
Welcome to the MySQL monitor.  Commands end with ; or \g.
[...]

However I don't have that much success from the host:

> mysql -P 12345 -uroot
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

Even more details

• I've seen that there's a question which looks like mine. However, it isn't the same (and it doesn't have any answers anyway)
  • I've seen that there are images dedicated to mysql, but I didn't have more success with them
  • My grep -v may feel weird. Admittedly, there may be cleaner way to do it. But when I attach my image, I can observe it actually worked as expected (ie: removed the bind-address). And I can see in the container /var/log/mysql/error.log:

Server hostname (bind-address): '0.0.0.0'; port: 3306 - '0.0.0.0' resolves to '0.0.0.0'; Server socket created on IP: '0.0.0.0'.

Answer 1

If your Docker MySQL host is running correctly you can connect to it from local machine, but you should specify host, port and protocol like this:

mysql -h localhost -P 3306 --protocol=tcp -u root

Change 3306 to port number you have forwarded from Docker container (in your case it will be 12345).

Because you are running MySQL inside Docker container, socket is not available and you need to connect through TCP. Setting "--protocol" in the mysql command will change that.