Sharing a MySQL Database Across Docker Containers
There are instances where you may have a database that is running on a host machine that you want to access from inside a container. There are three ways to do this depending on the situation.
Using the Host Network
The host networking mode will make the container use the same network as the host machine. This means the host machine and the container share the same IP and ports. So localhost inside the container is the same localhost in the host and you can connect to MySQL as if it was running in the same machine using localhost.
1 | docker run --network="host" <container> |
This can be limiting in a lot of cases as you don’t have the flexibility of an isolated container network with different ports and IP.
Using the Docker Bridge Network
Docker by default creates a network interface docker0 on the host that all containers running on the host machine use. You can then use the IP address of host on the docker0 (run sudo ip addr show docker0 on the host) interface to connect from inside the container. The catch here is you will have to enable remote access to MySQL by setting the bind-address = 0.0.0.0. This is usually a no-go for most situations.
Sharing the MySQL Socket
Docker allows you to mount directories on your host machine to container. We can use this to share the socket used by MySQL. The socket is usually found at /var/run/mysqld/mysqld.sock.
1 | docker run -v /var/run/mysqld:/host/mysqld <container> |
Now we can access the sock file inside the Docker container mounted at /host/mysqld/mysqld.sock and connect to MySQL using the socket.