Although it IS possible to connect from a container to a host service with unused IP attach docs.docker.comdocker-for-macnetworking.

The MySql is running on localhost and not exposing a port to the outside world, so its bound on localhost, not bound on the ip address of the machine.

Even if you have the IP address of the docker host it does not mean you can connect to docker host from within the container given that IP address as your Docker network may be overlay, host, bridge, macvlan, none etc which restricts the reachability of that IP address.

A fix has been submitted on March the 8th, 2019 and will hopefully be merged to the code base.

Until then, a workaround is to use a container as described in qoomons answer.

Both the docker host and the docker containers have an IP address on that bridge.

Such a container will share the network stack with the docker host and from the container point of view, localhost (or 127.0.0.1 ) will refer to the docker host.

That means your MySQL server could be reached from the Internet; make sure to setup firewall rules accordingly.

Oracle is a registered trademark of Oracle Corporation andor its affiliates.

I havent tried but I would assume you could create a separate network to connect containers over their own bridge offering them a common localhost.

You can bind whichever IP you want, just make sure youre not using it to anything else.

IN docker, one would expect that the hook docker.for.mac.localhost would be a generic docker internal name that would be valid for any operating system, not just for Mac.

When I docker run -e HOSTNAME docker.for.mac.host.internal, the container is created but nothign happens.

With --nethost -e HOSTNAMElocalhost at least the container runs and complains that it cant find the service I need (MySQL db).

The major problem is to get dynamically with a simple script that works both in Linux and OSX the host IP address.

I did this script that works in both environments (even in Linux distribution with LANG en configured).

The mysql client library even uses unix sockets by default when connecting to localhost rather than actually making a connection to localhost.

A unix socket avoids the overhead of the TCP stack and routing, and should run faster.

This enables the use of 1278 for local routing purposes ( default FALSE ).

I needed to do something similar, that is connect from my Docker container to my localhost, which was running the Azure Storage Emulator and CosmosDB Emulator.

When accessing your DB, remember to use the name you specified before, in this case dockerhost and the port of your host in which the DB is running.

Microsoft is completely silent on this when it talks about connecting to MSSQL from within a Docker container.

Docker For Mac Api